Calculate ΔHrxn for
Ca(s) + 1/2 O2(g) + CO2(g) → CaCO3(s)
given the following set of reactions:
Ca(s) + 1/2 O2(g) →CaO(s) ΔH = −635.1 kJ
CaCO3(s) → CaO(s) + CO2(g) ΔH = 178.3 kJ
_____ kJ

Answers

Answer 1

The enthalpy change of the reaction is -456.8 kJ.

The balanced chemical equation of the reaction is as follows:

Ca(s) + 1/2O2(g) + CO2(g) → CaCO3(s)

Given reactions:

Ca(s) + 1/2O2(g) → CaO(s) ΔH = -635.1 kJ/mol

CaCO3(s) → CaO(s) + CO2(g) ΔH = 178.3 kJ/mol

The target reaction is a combination of the two given reactions, hence the enthalpy change of the target reaction is the sum of the enthalpies of the two given reactions. It means that:

ΔHrxn = ΔH1 + ΔH2

We have:ΔH1 = -635.1 kJ/mol

ΔH2 = 178.3 kJ/mol

Therefore,ΔHrxn = ΔH1 + ΔH2= (-635.1 kJ/mol) + (178.3 kJ/mol)= -456.8 kJ/mol

Therefore, the enthalpy change of the reaction is -456.8 kJ.

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Related Questions

A vessel with a volume of 22.8 L contains 2.80 g of nitrogen gas, 0.807 g of hydrogen gas, and 79.9 g of argon gas. At 25°C, what is the pressure in the vessel? (Use 3 sig figs no need to type down the unit)

Answers

The pressure of the vessel at 25°C is 8.5 atm.

Volume of the vessel (V) = 22.8 LNitrogen gas (N₂) = 2.80 gHydrogen gas (H₂) = 0.807 gArgon gas (Ar) = 79.9 gTemperature (T) = 25°C = 298 KFormula usedThe total pressure of the mixture of gases is equal to the sum of the partial pressure of each gas.  Ptotal = Pn2 + PH2 + Par Moles of each gas is given by,  n = mass / molar massPartial pressure is given by the formula,P = (nRT) / VWhere, R is the gas constantR = 0.0821 (L x atm) / (mol x K)CalculationThe number of moles of each gas is given by;For Nitrogen gasNumber of moles (n) = mass / molar massmolar mass of nitrogen, N₂ = 14 + 14 = 28 gmol⁻¹nN₂ = 2.80 / 28 = 0.1 molFor Hydrogen gasNumber of moles (n) = mass / molar massmolar mass of hydrogen, H₂ = 1 + 1 = 2 gmol⁻¹nH₂ = 0.807 / 2 = 0.4 molFor Argon gasNumber of moles (n) = mass / molar massmolar mass of argon, Ar = 40 gmol⁻¹nAr = 79.9 / 40 = 2 molNow we can calculate the partial pressures of each gasPartial pressure of nitrogen gas,Pn2 = (nN₂RT) / V = [(0.1)(0.0821)(298)] / 22.8 = 0.34 atmPartial pressure of hydrogen gas,PH2 = (nH₂RT) / V = [(0.4)(0.0821)(298)] / 22.8 = 1.4 atmPartial pressure of argon gas,Par = (nArRT) / V = [(2)(0.0821)(298)] / 22.8 = 6.7 atmTotal pressure of the gas,Ptotal = Pn2 + PH2 + Par = 0.34 + 1.4 + 6.7 = 8.5 atmTherefore, the pressure of the vessel at 25°C is 8.5 atm.

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in the sulfite test, there are three possible redox reactions for the three ions in this series that can be oxidized by permanganate. the half-reaction method of balancing redox reactions will be useful. in all cases, permanganate is reduced in acidic conditions to mn2 . the first oxidation is sulfide ions to elemental sulfur. write the balanced net-ionic equation for this redox reaction.

Answers

The balanced net-ionic equation for the redox reaction as:

S²⁻ + 2e⁻ + 8H⁺ + MnO₄⁻ -> S + Mn²⁺ + 4H₂O

To write the balanced net-ionic equation for the oxidation of sulfide ions (S²⁻) to elemental sulfur (S) by permanganate (MnO₄⁻) in acidic conditions, we can follow the half-reaction method for balancing redox reactions.

The half-reaction for the oxidation of sulfide ions to elemental sulfur can be written as follows:

S²⁻ -> S

To balance this half-reaction, we need to add electrons (e⁻) to the left-hand side to balance the charge. Since sulfide ions have a charge of 2-, we need to add two electrons:

S²⁻ + 2⁻ -> S

Now, let's consider the reduction of permanganate (MnO₄⁻) to Mn²⁺ in acidic conditions. The balanced half-reaction for this reduction can be written as:

8H⁺ + MnO₄⁻ + 5e⁻ -> Mn²⁺ + 4H₂O

Finally, by combining the oxidation and reduction half-reactions, we can write the balanced net-ionic equation for the redox reaction as:

S²⁻ + 2e⁻ + 8H⁺ + MnO₄⁻ -> S + Mn²⁺ + 4H₂O

This equation represents the balanced net-ionic equation for the oxidation of sulfide ions to elemental sulfur by permanganate in acidic conditions.

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write the full ground‑state electron configuration for that element.
a. S: b. Kr :
c. Cs :

Answers

The ground‑state electron configuration of element sulfur (S) is; 1s² 2s² 2p⁶ 3s² 3p⁴, element krypton (Kr) is; 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶, and the element cesium (Ce) is; 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s¹.

The element S represents sulfur, which has an atomic number of 16. The full ground-state electron configuration for sulfur is obtained by filling up the orbitals with electrons according to the Aufbau principle and the Pauli exclusion principle.

Starting with the lowest energy level, the 1s orbital can hold a maximum of 2 electrons. Moving to the next energy level, the 2s orbital is filled with 2 electrons as well. Then, the 2p orbital is filled with a total of 6 electrons, distributed among its three sub-orbitals (2px, 2py, 2pz).

Putting it all together, the full ground-state electron configuration for sulfur is 1s² 2s² 2p⁶ 3s² 3p⁴.

The element Kr represents krypton, which has an atomic number of 36. Similarly, we follow the Aufbau principle and the Pauli exclusion principle to determine the electron configuration.

Starting with the 1s orbital, it is filled with 2 electrons. Then, the 2s orbital is filled with 2 electrons as well. After that, the 2p orbital is filled with 6 electrons. Moving on to the 3s and 3p orbitals, they are also filled with a total of 10 electrons.

The electron configuration continues with the 4s², 3d¹⁰, 4p⁶, 5s², 4d¹⁰, and finally, the 5p⁶ orbitals.

The full ground-state electron configuration for krypton is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶.

The element symbol Cs, can be explained by the filling of electrons in the various atomic orbitals according to the Aufbau principle and the Pauli exclusion principle.

The electron configuration begins with the 1s orbital, which can hold a maximum of 2 electrons. In cesium, it is filled with 2 electrons.

Next, we move to the 2s orbital, which is also filled with 2 electrons. Then, the 2p orbital is filled with 6 electrons, distributed among its three sub-orbitals (2px, 2py, 2pz).

Moving on to the third energy level, the 3s orbital is filled with 2 electrons, followed by the 3p orbital, which is filled with 6 electrons. Continuing to the fourth energy level, the 4s orbital is filled with 2 electrons, and then the 3d orbital is filled with 10 electrons.

In the fifth energy level, the 4p orbital is filled with 6 electrons. Next, the 5s orbital is filled with 2 electrons, and then the 4d orbital is filled with 10 electrons. Finally, in the sixth energy level, the 5p orbital is filled with 6 electrons, and the last electron goes into the 6s orbital.

Therefore, the full ground-state electron configuration for cesium is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s¹.

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Since energy cannot disappear, what happened to the rest of the heat created during the combustion process?

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The rest of the heat created during the combustion process is transferred to the surroundings through conduction, convection, and radiation.

What is the law of conservation of energy?

The principle of conservation of energy asserts that energy cannot be generated or annihilated but can solely undergo transformation from one form to another. This signifies that the overall energy within an isolated system remains unaltered.

Throughout the combustion process, the fundamental principle of energy conservation remains upheld, ensuring the preservation of energy. The residual heat generated during combustion undergoes a transfer to the surrounding environment through a multitude of mechanisms. These mechanisms encompass conduction, convection, and radiation.

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When we react a weak acid with a weak base, the pH of the solution is dependent on: Select the correct answer below: O K, of the acid O K, of the base both of the above none of the above

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When we react a weak acid with a weak base, the pH of the solution is dependent on both the K, of the acid and K, of the base.

The pH of a solution is directly proportional to the concentration of H+ ions in the solution, and inversely proportional to the concentration of OH- ions in the solution. Therefore, the pH of the solution depends on the strength of both the acid and the base involved in the reaction.

The strength of an acid is determined by its acid dissociation constant, also known as Ka. The higher the value of Ka, the stronger the acid. Similarly, the strength of a base is determined by its base dissociation constant, also known as Kb. The higher the value of Kb, the stronger the base.

When a weak acid reacts with a weak base, a salt is formed, along with water. The pH of the resulting solution depends on the extent of the reaction, which in turn depends on the values of Ka and Kb of the acid and base, respectively. If the Ka of the acid is higher than the Kb of the base, the solution will be acidic, and if the Kb of the base is higher than the Ka of the acid, the solution will be basic. If the values of Ka and Kb are roughly equal, the resulting solution will be neutral.

Therefore, when we react a weak acid with a weak base, the pH of the solution is dependent on both the K, of the acid and K, of the base.

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in the syntehsis of hexaphenylbenzene, why is the intially form bicyclic adduct nto isolated

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In the synthesis of hexaphenylbenzene, the initially formed bicyclic adduct is not isolated because it serves as an intermediate in the reaction and undergoes further transformation to yield the desired final product.

Hexaphenylbenzene is synthesized through a series of steps, typically starting from a triphenylalkene precursor. The initial reaction involves the reaction of the triphenylalkene with a strong base, such as n-butyllithium, to generate a reactive carbanion.

The carbanion reacts with a dihalide, such as dihalobenzene, via a cycloaddition reaction to form a bicyclic adduct. This adduct contains a bridged structure formed by the combination of the triphenylalkene and dihalobenzene moieties.

However, this bicyclic adduct is not the final product of interest, which is hexaphenylbenzene. To convert the adduct into the desired product, the reaction typically involves a thermal or chemical rearrangement, such as a retro-Diels-Alder reaction or a reductive elimination process. These subsequent steps result in the formation of the hexaphenylbenzene molecule.

Therefore, the isolation of the initially formed bicyclic adduct is unnecessary as it is an intermediate in the reaction sequence and not the final target compound.

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Nuclear binding energy, ΔE, is the energy required to break a nucleus into its componentnucleons (protons and neutrons). It can also be defined as the energy produced when a nucleus forms from its component nucleons. Using Einstein's equation one can calculate nuclear binding energy in joules:
ΔE=Δmc2
where Δm is the mass defect (mass lost) in kilograms and c is the speed of light in meters per second. The mass defect is the difference in mass between the nucleus and its components.
The stability of different nuclei can be compared by using the average nuclear binding energy per nucleon, which can be obtained by dividing the nuclear binding energy by the mass number.
Constants and conversion factors
The atomic mass of 5525Mn is 54.938 amu.
The speed of light is c = 3.00×108 m/s .
The mass of a proton is 1.0073 amu .
The mass of a neutron is 1.0087 amu .
The mass of an electron is 5.4858×10−4 amu .
1 kg=6.022×1026 amu.
1 J=1 kg⋅m2/s2.
1 MeV=1.602×10−13 J.
Calculate the nuclear binding energy of 5525Mn in joules.
Express your answer numerically in joules.

Answers

The nuclear binding energy of 5525Mn is approximately 1.127×10^13 joules.

. To calculate the nuclear binding energy, we need to determine the mass defect (Δm) of 5525Mn. The mass defect is the difference in mass between the nucleus and its components, which are protons and neutrons. By calculating the mass of the protons and neutrons, subtracting the mass of the nucleus, converting the mass defect to kilograms, and using Einstein's equation ΔE = Δm × c^2, we find that the nuclear binding energy of 5525Mn is approximately 1.127×10^13 joules. This value represents the energy required to break the nucleus into its component nucleons or the energy released when the nucleus forms from its components.

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The decomposition of HI(g) is represented by the equation

2HI(g) = H2(g) + I2(g)

The following experiment was devised to determine the equilibrium constant of the reaction.

HI (g) is introduced into five identical 400-cm3 glass bulbs, and the five bulbs are maintained at 623 K. The amount of I2 produced over time is measured by opening each bulb and titrating the contents with 0. 0150 M Na2S2O3 (aq). The reaction of I2 with the titrant is

I2 + 2Na2S2O3 = Na2S4O6 + 2NaI

Data for the experiment are provided in this table.

Bulb Initial mass of HI (g) Time(hours) Volume of titrant(mL)

1 0. 0300 2 20. 96

2 0. 0320 4 27. 90

3 0. 315 12 32. 31

4 0. 406 20 41. 50

5 0. 280 40 28. 68

What is the value of Kc for the decomposition of HI at 623 K?

Answers

The value of Kc for the decomposition of HI at 623 K is 0.0168 [tex]M^-^1[/tex]

How do we calculate?

[tex]I_2[/tex] + [tex]2Na_2S_2O_3[/tex] → [tex]Na_2S_4O_6[/tex]+ 2NaI is the balanced equation:

moles of [tex]I_2[/tex]  = volume of titrant in mL)* (0.0150 mol/L) / 1000

for Bulb 1:

moles of [tex]I_2[/tex] = (20.96 mL) * (0.0150 mol/L) / 1000

= 0.003144 mol

The concentration of [tex]I_2[/tex]  = moles of I2 / volume of the bulb (in L)

 = 0.003144 mol / 0.400 L

  = 0.00786 M

The concentration of HI = initial mass of HI / molar mass of HI / volume of the bulb (in L)

  = 0.0300 g / 127.91 g/mol / 0.400 L

   = 0.592 M

Kc = ([H2] * [[tex]I_2[/tex]]) / ([HI]²)

Kc = [[tex]I_2[/tex]] / ([HI]²)

Kc = (0.00786 M) / (0.592 M)²

Kc  = 0.022 [tex]M^-^1[/tex]

The Kc for each bulb

Bulb 2: Kc = 0.00834 M / (0.640 M)² = 0.020

Bulb 3: Kc = 0.00950 M / (0.788 M))²  = 0.015

Bulb 4: Kc = 0.0122 M / (1.03 M))²  = 0.011

Bulb 5: Kc = 0.00818 M / (0.710 M))²  = 0.016

In conclusion, the average Kc

= (0.022 + 0.020 + 0.015 + 0.011 + 0.016) / 5

= 0.0168 [tex]M^-^1[/tex]

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Draw the Lewis structure of BrCl₄⁻ and then determine its electron domain and molecular geometries.

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The Lewis structure of BrCl₄⁻, or tetrachlorobromate ion, consists of a central bromine atom (Br) bonded to four chlorine atoms (Cl) and one additional negative charge (-). The structure is as follows:

Br

|

Cl-Cl

|

Cl

The electron domain geometry of BrCl₄⁻ is tetrahedral. This is because there are four bonding pairs and one lone pair of electrons around the central bromine atom. The presence of the lone pair influences the overall shape.

The molecular geometry of BrCl₄⁻ is also tetrahedral. The four chlorine atoms and the lone pair of electrons around the bromine atom repel each other, leading to a symmetric arrangement in three-dimensional space.

In summary, the Lewis structure of BrCl₄⁻ shows a central bromine atom bonded to four chlorine atoms and one additional negative charge. The electron domain geometry is tetrahedral due to the presence of four bonding pairs and one lone pair of electrons. The molecular geometry is also tetrahedral, resulting from the repulsion between the chlorine atoms and the lone pair around the central bromine atom.

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calculate the volume of a kilogram of magnesium (density = 1.74 g/cm3).

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To calculate the volume of a kilogram of magnesium, we need to convert the density from grams per cubic centimeter (g/cm³) to kilograms per cubic meter (kg/m³) since the mass is given in kilograms.

Given:

Density of magnesium = 1.74 g/cm³

To convert the density from g/cm³ to kg/m³, we divide the density by 1000 since there are 1000 grams in a kilogram and 1,000,000 cubic centimeters in a cubic meter.

Density of magnesium = 1.74 g/cm³ = 1.74 kg/m³

Next, we can use the formula:

Density = Mass / Volume

Rearranging the formula to solve for volume:

Volume = Mass / Density

Mass of magnesium = 1 kilogram

Substituting the values into the formula:

Volume = 1 kg / 1.74 kg/m³

Simplifying, we find:

Volume = 0.574 m³

Therefore, the volume of 1 kilogram of magnesium is 0.574 cubic meters.

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why does the temperature of the reaction mixture drop (as opposed to remaining constant) once the reaction reaches the stoichiometric point? ng 5

Answers

The temperature of the reaction mixture drops once the reaction reaches the stoichiometric point due to the release of excess heat energy generated during the reaction.

During a chemical reaction, heat energy can be either released or absorbed. In an exothermic reaction, heat is released as a product, while in an endothermic reaction, heat is absorbed from the surroundings. When a reaction is not at its stoichiometric point, there is an excess of one or more reactants present. As the reaction progresses towards the stoichiometric point, the reactants are consumed, and the reactant concentration decreases.

At the stoichiometric point, the reactants are in the ideal ratio according to the balanced chemical equation. Any additional reactant beyond this point becomes excess and is no longer needed for the reaction. The excess reactant molecules do not participate in the reaction but continue to collide with each other, leading to intermolecular interactions and the release of excess heat energy. This excess heat energy dissipates into the surroundings, causing a drop in the temperature of the reaction mixture.

The decrease in temperature at the stoichiometric point is a result of the endothermic nature of the excess heat release, counteracting the exothermic nature of the reaction up to that point. This phenomenon is commonly observed in various chemical reactions and provides important insights into the energy changes occurring during the reaction process.

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a reaction of the stoichiometry is started with 0.0 m and 2.0 m. at a certain time 1.0 m and the concentrations of are

Answers

By using the stoichiometry of the reaction and the given initial and final concentrations of S, [Q]* = 1.5 M, [R]* = 1.0 M (Option 4)

To determine the concentrations of Q and R at time t = t*, we can use the stoichiometry of the reaction and the given initial and final concentrations of S.

The stoichiometry of the reaction is: Q + 2R --> 2S

Initially, we have [S]₀ = 0.0 M, [Q]₀ = [R]₀ = 2.0 M

At time t = t*, [S]* = 1.0 M.

Since 2 moles of S are produced for every mole of Q, and each mole of S is produced from 2 moles of R, the decrease in concentration of S from 2.0 M to 1.0 M indicates the consumption of 1 mole of S.

Therefore, we can conclude that 0.5 moles of Q and 1 mole of R were consumed to produce 1 mole of S.

Starting with [Q]₀ = [R]₀ = 2.0 M, and taking into account the consumption of 0.5 moles of Q and 1 mole of R, we can calculate the concentrations at time t = t*:

[Q]* = [Q]₀ - (0.5 mol/L) = 2.0 M - 0.5 M = 1.5 M

[R]* = [R]₀ - (1 mol/L) = 2.0 M - 1.0 M = 1.0 M

Therefore, the concentrations of Q and R at time t = t* are:

[Q]* = 1.5 M

[R]* = 1.0 M

So, the correct answer is:

[Q]* = 1.5 M, [R]* = 1.0 M.

The correct question is:

A reaction of the stoichiometry Q + 2R --> 2S is started with [S]₀ = 0.0 M and [Q]₀ =[R]₀  = 2.0 M . At a certain time, t =t* , [S]* = 1.0 M.

At time t =t* , the concentrations of Q and R are:

[Q]* = 1.0 M,  [R]* = 0.0 M .[Q]* = 1.0 M, [R]* = 1.0 M .none of these[Q]* = 1.5 M , [R]* = 1.0 M .[Q]* = 1.0 M , [R]* = 1.5 M .

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1. the displacement by oh- on ch3ch2i in (a) ethanol or (b) dimethyl sulfoxide.

Answers

The displacement by OH- on CH3CH2I in (a) ethanol is favored due to the stronger solvation of the nucleophile.

When considering the displacement of a leaving group by a nucleophile, the nature of the solvent plays an important role. In this case, we are comparing the solvents ethanol and dimethyl sulfoxide (DMSO).

Ethanol is a polar protic solvent, meaning it can donate hydrogen bonds and has a positive hydrogen atom. On the other hand, DMSO is a polar aprotic solvent, lacking a hydrogen atom that can be easily donated.

In a polar protic solvent like ethanol, the nucleophile (OH-) can readily form hydrogen bonds with the solvent molecules, making it more solvated. The solvation of the nucleophile reduces its reactivity and slows down the reaction.

In a polar aprotic solvent like DMSO, the nucleophile is not as strongly solvated, allowing for a higher concentration of the nucleophile and increased reactivity. As a result, the displacement reaction by OH- on CH3CH2I in DMSO is generally faster compared to ethanol.

:

The displacement reaction by OH- on CH3CH2I is favored in ethanol due to the stronger solvation of the nucleophile, which reduces its reactivity.

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What are the units of k in the following rate law? Rate= k[x]^2[y]^2 a. 1/Ms^2 b. 1/M^2s c. M^2s d. M^2/s e. 1/M^3s

Answers

The units of k in the given rate law are 1/M^3s, which corresponds to option e.

What is the rate law?

By examining the units of the rate equation, it is possible to establish the units of the rate constant (k). The units of the rate constant can be found by canceling out the units of concentration raised to the proper power because the rate is represented in terms of concentrations.

In this instance, both the rate and the concentration of the reactants x and y are expressed in units of M. The units of the rate constant (k) should be as follows in order to cancel out the units of concentration increased to the power of four:

k = (M/s) / (M^2)^2 = M^-3s^-1

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a 4.87 g sample of aluminum reacts with oxygen to form 7.93 g of aluminum oxide. what is the mass percent of oxygen in the aluminum oxide?

Answers

To calculate the mass percent of oxygen in aluminum oxide, we need to determine the mass of oxygen in the compound and divide it by the total mass of aluminum oxide. This value is then multiplied by 100 to express it as a percentage.

First, we calculate the mass of oxygen by subtracting the mass of aluminum from the total mass of aluminum oxide.

Mass of oxygen = Mass of aluminum oxide - Mass of aluminum

Mass of oxygen = 7.93 g - 4.87 g = 3.06 g

Next, we calculate the mass percent of oxygen by dividing the mass of oxygen by the total mass of aluminum oxide and multiplying by 100.

Mass percent of oxygen = (Mass of oxygen / Total mass of aluminum oxide) x 100

Mass percent of oxygen = (3.06 g / 7.93 g) x 100 ≈ 38.6%

Therefore, the mass percent of oxygen in the aluminum oxide is approximately 38.6%.

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Propose a synthesis of the compound shown below starting with 4-methoxycinnamic acid. Use the Hunsdiecker reaction as one of the steps in your synthesis.

Answers

For the synthesis of ethyl trans-4-methoxycinnamate from 4-methoxy cinnamic acid, we can protect the carboxylic acid group through esterification, perform the Hunsdiecker reaction to introduce a bromine atom, and then substitute the bromine with an ethyl group.

To synthesize ethyl trans-4-methoxycinnamate starting from 4-methoxy cinnamic acid, we can follow the following steps:

The carboxylic acid group in 4-methoxy cinnamic acid needs to be protected to avoid unwanted reactions. This can be achieved by converting it into an ester.

We can react 4-methoxy cinnamic acid with an alcohol, such as methanol or ethanol, in the presence of a strong acid catalyst (e.g., sulfuric acid) to form the corresponding methyl or ethyl ester.

4-Methoxy cinnamic acid + Methanol (or Ethanol) → Methyl (or Ethyl) 4-methoxy cinnamate

The Hunsdiecker reaction is a useful transformation to convert carboxylic acids with a methylene group adjacent to the carboxyl group into the corresponding alkyl halides. In this case, we will convert the ethyl 4-methoxy cinnamate ester into the corresponding ethyl 4-methoxy cinnamate bromide.

Ethyl 4-methoxy cinnamate + Bromine (Br₂) + Carbon tetrachloride (CCl₄) → Ethyl 4-methoxy cinnamate bromide

To remove the bromine atom introduced in the previous step, we can perform an elimination reaction using a strong base. For example, treatment with potassium hydroxide (KOH) in an alcoholic solvent can lead to the elimination of bromine and the formation of the desired ethyl trans-4-methoxycinnamate.

Ethyl 4-methoxy cinnamate bromide + Potassium hydroxide (KOH) → Ethyl trans-4-methoxycinnamate

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The complete question is:

Propose a synthesis of the compound ethyl trans-4-methoxycinnamate starting with 4-methoxy cinnamic acid. Use the Hunsdiecker reaction as one of the steps in your synthesis.

a gas starts out with a volume of 516 ml at a pressure of 345 torr. if the volume decreases to 213 ml but the temperature doesnt cahnge what is the new pressure

Answers

The new pressure of the gas is approximately 838.74 torr.

To determine the new pressure of the gas, we can use Boyle's Law, which states that the pressure and volume of a gas are inversely proportional when the temperature remains constant.

According to Boyle's Law, P1 * V1 = P2 * V2, where P1 and V1 are the initial pressure and volume, and P2 and V2 are the final pressure and volume.

Given:

Initial volume (V1) = 516 ml

Initial pressure (P1) = 345 torr

Final volume (V2) = 213 ml

Using the formula and plugging in the values:

345 torr * 516 ml = P2 * 213 ml

Simplifying the equation:

P2 = (345 torr * 516 ml) / 213 ml

Calculating the value:

P2 ≈ 838.74 torr

Therefore, the gas now has a pressure of approximately 838.74 torr.

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to what volume must 1.0 l of a 6.0 m solution of hcl be diluted in order to prepare a 0.2 m solution? select one: a. 30 l b. 20 l c. 10 l d. 40 l

Answers

Answer:

A

Explanation:

To determine the volume required to dilute a 1.0 L solution of 6.0 M HCl to a 0.2 M solution, we can use the equation for dilution:

M1V1 = M2V2

Where:

M1 = Initial concentration of the solution (6.0 M)

V1 = Initial volume of the solution (1.0 L)

M2 = Final concentration of the solution (0.2 M)

V2 = Final volume of the solution (unknown)

Rearranging the equation, we have:

V2 = (M1/M2) * V1

Plugging in the values:

V2 = (6.0 M / 0.2 M) * 1.0 L

V2 = 30 L

Therefore, the volume required to dilute the 1.0 L solution of 6.0 M HCl to a 0.2 M solution is 30 liters (option a).

The acid-dissociation constant of hydrocyanic acid (HCN) at 25.0 deg C is 4.9 x 10^-10. What is the pH of an aqueous solution of 0.080 M sodium cyanide (NaCN)?
Please show all your work thanks

Answers

The pH of the aqueous solution of 0.080 M sodium cyanide (NaCN) is  1.105.

How do we calculate?

NaCN dissociates in water to form Na+ ions and CN- ions.  then  react with water in a hydrolysis reaction:

CN- + [tex]H_2O[/tex]⇌ HCN + OH-

The hydrolysis of CN- ions results in the formation of hydrocyanic acid (HCN) and hydroxide ions (OH-).

Since HCN is a weak acid, it will  dissociate partially in order  to release H+ ions:

HCN ⇌ H+ + CN-

Ka = [H+][CN-] / [HCN]

and  [CN-] = 0.080 M

[tex]4.9 * 10^-^1^0[/tex] = x * 0.080 / (0.080 - x)

[tex]4.9 * 10^-^1^0[/tex] * (0.080 - x) = x * 0.080

[tex]0.392 * 10^-^1^0[/tex] - [tex]4.9 * 10^-^1^0[/tex] * x = 0.080 x

[tex]0.392 * 10^-^1^0[/tex] = 0.080 x + [tex]4.9 * 10^-^1^0[/tex] * x

x =  0.0784 M

pH = -log[H+]

pH = -log(0.0784)

pH = 1.105

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For the reaction of hypochlorite anion with iodide anion, the iodide anion acts as the reducing agent according to the following oxidation half-reaction: 21- (aq) + I2 (aq) + 2e Which of the following reduction half-reactions is correct to give the overall reaction of hypochlorite anion with iodide anion? (A) CIO (aq) + 2e + C (aq) + H2O (1) (B) H+ (aq) + C10 (aq) + e → C (aq) + H2O (1) (C) 2H+ (aq) + C10 (aq) + 2e + Cl(aq) + H20 (1)

Answers

The reduction half-reaction that is correct to give the overall reaction of hypochlorite anion with iodide anion is; 2H⁺ (aq) + ClO⁻ (aq) + 2e⁻ → Cl⁻ (aq) + H₂O (l). Option C is correct.

To determine the correct reduction half-reaction that gives the overall reaction of hypochlorite anion (ClO⁻) with iodide anion (I⁻), we need to consider the conservation of charge and atoms.

The oxidation half-reaction given is;

I⁻ (aq) + I₂ (aq) + 2e⁻ → 2I⁻ (aq)

In this reaction, iodide ion (I⁻) is oxidized to form iodine (I₂) by losing two electrons.

To balance this with a reduction half-reaction, we need to find a reaction that involves the reduction of hypochlorite anion (ClO⁻) while simultaneously consuming the electrons produced in the oxidation half-reaction.

Therefore, the correct reduction half-reaction will be:

2H⁺ (aq) + ClO⁻ (aq) + 2e⁻ → Cl⁻ (aq) + H₂O (l)

In this reaction, hypochlorite anion (ClO⁻) is reduced to chloride ion (Cl⁻) by gaining two electrons, which balances the oxidation half-reaction. The addition of two hydrogen ions (2H⁺) and the formation of water (H₂O) completes the balanced reduction half-reaction.

Hence, C. is the correct option.

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Consider the following chromatographic data. Length of column 15.3 cm Flow rate 0.563 mL/min Volume of mobile phase 2.43 mL Volume of stationary phase 0.195 mL Base Peak Width (minutes) Retention Time (minutes) 0.53 1.73 2.64 3.02 8.41 Component Nonretained 0.45 0.78 1.22 1.45 Calculate the following a. partition coefficient (K) for peak B b. H based on peak C c. resolution of peaks B and C d. k' for component D

Answers

a) The partition coefficient for peak B is 4.87.

b) H based on peak C is 10.84.

c) The resolution of peaks B and C is 6.75.

d) The k' for component D is 2.22.

Chromatography is an important analytical technique used to separate, identify, and quantify components in complex mixtures. Chromatography is based on the principle of differential partitioning between a stationary phase and a mobile phase. Chromatography can be used in various fields such as chemistry, biochemistry, forensics, and others. In this chromatographic data, the length of the column is 15.3 cm, flow rate is 0.563 mL/min, the volume of the mobile phase is 2.43 mL, and the volume of the stationary phase is 0.195 mL. The base peak width for the given data is 0.53 minutes, and retention time is given in minutes for different components. The component non-retained is 0.45 minutes. Now, we will calculate the required parameters a, b, c, and d. a. Partition Coefficient (K) for peak BThe partition coefficient is the ratio of the concentration of the solute in the stationary phase to the concentration of the solute in the mobile phase. The partition coefficient for peak B can be calculated as:Partition coefficient (K) = (tR - t0)/t0Where tR is the retention time of the peak B and t0 is the non-retention time of the solvent. Here, tR = 2.64 minutes and t0 = 0.45 minutes.K = (2.64 - 0.45)/0.45K = 4.87Therefore, the partition coefficient for peak B is 4.87.b. H based on peak CH is defined as the difference in the retention time of peak C and peak B divided by the base peak width. The H value can be calculated as:H = (tR, C - tR, B)/WBWhere tR, C is the retention time for peak C, tR, B is the retention time for peak B, and WB is the base peak width. Here, tR, C = 8.41 minutes, tR, B = 2.64 minutes, and WB = 0.53 minutes.H = (8.41 - 2.64)/0.53H = 10.84Therefore, H based on peak C is 10.84.c. Resolution of peaks B and CThe resolution of two peaks is the separation between them and can be calculated as:Resolution (R) = 2[(tR, C - tR, B)/(wB + wC)]Where wB and wC are the base peak widths for peaks B and C, respectively. Here, wB = wC = 0.53 minutes.R = 2[(8.41 - 2.64)/(0.53 + 0.53)]R = 6.75Therefore, the resolution of peaks B and C is 6.75.d. k' for component DThe k' value is defined as the retention factor for a component, and it can be calculated as:k' = (tR - t0)/t0Where tR is the retention time of component D and t0 is the non-retention time of the solvent. Here, tR = 1.45 minutes and t0 = 0.45 minutes.k' = (1.45 - 0.45)/0.45k' = 2.22Therefore, the k' for component D is 2.22.

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How do the numbers in the “R3” and “T2” columns compare?

Answers

The R3 and T2 columns provide information about the quality of the regression model. The t-value is used to determine the significance of each coefficient, while the R-squared value indicates how well the model fits the data.

In statistics, the R-squared value and the t-value are both significant indicators of a model's goodness of fit. The R-squared value, often known as the correlation coefficient, is a measure of how well the model fits the data. A correlation coefficient value ranges from -1 to +1, with 0 indicating no correlation and 1 indicating a perfect positive correlation. A negative 1 indicates a perfect negative correlation.The t-value indicates whether the coefficient is statistically significant or not. If the p-value is less than the chosen alpha level, the t-value is significant.The R3 and T2 columns are related to the regression model's goodness of fit. The t-value column contains the t-statistic for each coefficient, while the R-squared column contains the R-squared value for the model. The t-value, as previously stated, is used to test the hypothesis that each coefficient is zero. The coefficient is considered to be significant if the t-value is greater than the critical value. The R-squared value, on the other hand, measures how well the regression model fits the data. The R-squared value ranges from 0 to 1, with 1 indicating a perfect fit and 0 indicating no correlation between the model and the data. In general, higher R-squared values indicate a better fit.

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Calculate the pH of each of the following solutions. Keep 2 decimal places. Kb of NO2 = 2.5e-11 Kb of OCl = 2.9e-7 Ka of NH4+ = 5.6e-10 (a) 0.13 M KNO2 (b) 0.37 M NaOC (c) 0.48 M NHACIO 4

Answers

The pH of the solutions are approximately: (a) 3.40, (b) 7.46, (c) 0.32.

To calculate the pH of each solution, we need to determine the concentration of hydroxide ions (OH-) in the solution and then convert it to pH using the relationship: pH = -log10[OH-].

(a) 0.13 M KNO2:

KNO2 dissociates in water to form NO2- ions. Since we are given the Kb value for NO2, we can calculate the concentration of OH- ions using the Kb expression: Kb = [OH-][NO2-]/[NO2]. Given that the concentration of NO2- is equal to the concentration of KNO2 (0.13 M), we can set up the equation as follows:

2.5e-11 = [OH-][0.13]/[0.13]

[OH-] = 2.5e-11 M

pOH = -log10[OH-] ≈ 10.60

pH = 14 - pOH ≈ 3.40

(b) 0.37 M NaOCl:

NaOCl dissociates in water to form OCl- ions. We can use the Kb expression for OCl to calculate the concentration of OH- ions:

2.9e-7 = [OH-][OCl-]/[OCl]

[OH-] = 2.9e-7 M

pOH = -log10[OH-] ≈ 6.54

pH = 14 - pOH ≈ 7.46

(c) 0.48 M NHACIO4:

NHACIO4 is a strong acid, meaning it dissociates completely in water, releasing H+ ions. Therefore, the concentration of H+ ions in the solution is equal to the concentration of NHACIO4 (0.48 M).

pH = -log10[H+] = -log10[0.48] ≈ 0.32

In summary, the pH of the solutions are approximately: (a) 3.40, (b) 7.46, (c) 0.32.

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3 cu 8hno3 --> 3 cu(no3)2 2 no 4 h2o in the above equation how many grams of water can be made when 9 grams of hno3 are consumed? round your answer to the nearest tenth. if yo

Answers

In the given equation, , 1.26 g of water is produced when 9 grams of HNO₃ is consumed.

It looks like the equation is already balanced for you, so the first step will be to convert 9 grams of HNO₃ to moles. To do this find the molar mass, and use to to do your conversion.

Using the numbers provided for mass, this is the equation:

1(1.0) + 1(14) + 3(16) = 1 + 14 + 48 = 63 g/mol

[tex]9g HNO_{3} \times \frac{1 moleHNO_{3}}{63gHNO_{3} }[/tex]

= [tex]0.14\ mol\ HNO_{3}[/tex]

Now that you know how many moles of HNO₃  you're starting with, use the ratio of moles in the equation to find the moles of H2O produced. The coefficient of HNO₃ is 8, and H₂O is 4

[tex]0.14\ mol\ HNO_{3} \times \frac{4 mol\ H_{2}O }{8\ mol\ HNO_{3} }[/tex]

= 0.07mol water

Converting mole into mass by the formula-

Mass = Molar mass × Moles

Therefore, 0.07 mol × 18g/mol

Thus, 1.26 g of water is made when 9 grams of HNO₃ are consumed.

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A galvanic cell is powered by the following redox reaction: 2MnO−4(aq) + 16H+(aq) + 5Zn(s) → 2Mn+2(aq) + 8H2O(l) + 5Zn+2(aq) Answer the following questions about this cell. If you need any electrochemical data, be sure you get it from the ALEKS Data tab.
Write a balanced equation for the half-reaction that takes place at the cathode. Write a balanced equation for the half-reaction that takes place at the anode. Calculate the cell voltage under standard conditions.
Round your answer to 2 decimal places.
=E0
V

Answers

The balanced equation for the half-reaction that takes place at cathode is 2MnO₄⁻(aq) + 16H+(aq) + 10e⁻ → 2Mn₂+(aq) + 8H₂O(l). The balanced equation for the half-reaction that takes place at anode is 5Zn(s) → 5Zn₂+(aq) + 10e⁻. The cell voltage under standard conditions is 2.27 V.

To determine the balanced equations for the half-reactions that take place at the cathode and anode, we need to identify the oxidation states of each element and balance the charges.

Cathode half-reaction, Reduction occurs at the cathode.

The reduction half-reaction involves the reduction of MnO₄⁻ to Mn₂⁺.

2MnO₄⁻(aq) + 16H+(aq) + 10e⁻ → 2Mn₂+(aq) + 8H₂O(l)

Anode half-reaction, Oxidation occurs at the anode.

The oxidation half-reaction involves the oxidation of Zn to Zn₂⁺.

5Zn(s) → 5Zn₂+(aq) + 10e⁻

To calculate the cell voltage (E₀), we need the standard reduction potentials (E₀) for each half-reaction.

From the ALEKS Data tab, we find

E₀(MnO₄⁻/Mn₂⁺) = 1.51 V (reduction potential)

E₀(Zn₂⁺/Zn) = -0.76 V (oxidation potential)

The cell voltage (E0) under standard conditions can be calculated using the formula

E₀(cell) = E₀(cathode) - E₀(anode)

E₀(cell) = 1.51 V - (-0.76 V) = 2.27 V

Therefore, the cell voltage under standard conditions is 2.27 V.

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which of the following molecules or ions contain an oxygen atom with a positive formal charge?
a. CO2
b. CO
c. CO2^-2
d. H2O

Answers

Carbonate ions [tex]CO_2^{-2}[/tex] contain an oxygen atom with a favorable elevated charge. Thus, option C is correct.

The carbonate ion is a compound that is formed by sharing valency shell electrons of Carbon and Oxygen elements. After forming, the oxygen atom in the middle has a positive formal charge. This is because each oxygen atom in the carbon will be assigned a formal charge of -1.

In this reaction, when the compound is double-bonded, the oxygen atom in the middle has only six electrons in the valence shell instead of eight electrons, resulting in a positive formal charge of +2 after the reaction.

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A solution of the amino acid serine is at ph 1. what will be the overall charge and the charge on the two functional groups? serine has a pi of 5.68

Answers

The overall charge and the charge on the two functional groups (B) The side groups will be -COOH and -NH₃⁺. Overall, the charge will be positive.

At pH 1, the amino acid Serine exists in its protonated form due to the highly acidic conditions. The carboxyl group (-COOH) of Serine will be fully protonated, resulting in a positively charged -COOH²⁺ group.

Similarly, the amino group (-NH₂) will also be protonated, forming a positively charged -NH₃⁺ group. The overall charge of Serine at pH 1 will be positive because both functional groups are positively charged.

It is important to note that the pKa values of the carboxyl and amino groups of Serine are around 2.2 and 9.2, respectively. At pH 1, both groups are fully protonated and carry a positive charge. The isoelectric point (pI) of Serine, which represents a neutral charge, occurs at a pH of approximately 5.68.

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Complete question :

A solution of the amino acid Serine is at pH 1. What will be the overall charge and the charge on the two functional groups? Serine has a pl of 5.68

A) The side groups will be -COO and -NH.. Overall the charge will be neutral.

B) The side groups will be -COOH and -NH₃⁺. Overall the charge will be positive.

C)The side groups will be -COOH and -NH₂. Overall the charge will be neutral.

D) The side groups will be -COO and -NH. Overall the charge will be negative.

E) The side groups will be -COOH, and -NH:. Overall the charge will be positive.

14-39. Evaluate E' for the half-reaction 1 (CN)2(3)+2H+ + 2e = 2HCN(aq) Cyanogen Hydrogen cyanide 1 14-40. Calculate E' for the reaction H2C2O4 + 2H+ +2e = 2HCO2H E° = 0.204 V Oxalic acid Formic acid

Answers

The equation for the half-reaction is:

Cyanogen + Hydrogen ion + 2 electrons → Hydrogen cyanide

The balanced chemical equation for the given redox reaction is given by:CN2(3-) + 2H+ + 2e- → 2HCNFrom the given balanced equation:

Reactant: CN2(3-) and Product: HCN

In the balanced equation, number of electrons transferred = 2.The standard electrode potential, E° for this half-reaction is equal to 0.59 V.

Therefore, the E' for the given half-reaction can be calculated by using the following formula

:E'= E°-(0.0592/2) logQ

Where,

Q = [H+]^2[Cyanogen]/[Hydrogen cyanide] [H+] = 1.0M, [Cyanogen] = 1.0M, and [Hydrogen cyanide] = 1.0MTherefore,Q = (1.0)²(1.0)/(1.0)² = 1.0

Substituting the values of Q and E° in the above equation we get,

E' = 0.59-(0.0592/2) log1.0 = 0.59 - 0 = 0.59 Volts.

The equation for the given redox reaction is given by:

H2C2O4 + 2H+ + 2e- → 2HCO2H

The balanced chemical equation for the given redox reaction is given by:

Reactant: H2C2O4 and Product: HCO2H

In the balanced equation, number of electrons transferred = 2.The standard electrode potential, E° for this half-reaction is equal to 0.204 V.

Therefore, the E' for the given half-reaction can be calculated by using the following formula:

E' = E° - (0.0592/2) logQ

Where,

Q = [H+]²[Oxalic acid]/[Formic acid] [H+] = 1.0M, [Oxalic acid] = 1.0M, and [Formic acid] = 1.0MTherefore,Q = (1.0)²(1.0)/(1.0)² = 1.0

Substituting the values of Q and E° in the above equation we get,

E' = 0.204-(0.0592/2) log1.0 = 0.204 - 0 = 0.204 Volts.

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isabellaludlow101 avatar isabellaludlow101 09/28/2022 Chemistry College answered • expert verified Forensic scientist Samantha Monzon is collecting physical evidence at a crime scene where someone was murdered. What does this process MOST likely involve? A. She will place all items in an airtight, plastic container. B. She will have to leave weapons such as guns and knives at the scene. C. She will need to obtain a search warrant before she collects anything. D. She will collect anything that could be related to the crime.

Answers

The process of collecting physical evidence at a crime scene by forensic scientist Samantha Monzon would most likely involve: (D) She will collect anything that could be related to the crime.

Forensic scientists are trained to collect and preserve any potential evidence that could be relevant to the crime under investigation. This includes items such as weapons, personal belongings, biological samples, fingerprints, fibers, and any other potential traces left behind at the crime scene. The goal is to gather as much evidence as possible to aid in the investigation and provide a comprehensive analysis of the crime.

Regarding the other options:

A. While it is common for evidence to be stored in appropriate containers, the specific choice of an airtight, plastic container would depend on the nature of the evidence.

B. Weapons such as guns and knives would typically be collected as evidence, rather than being left at the scene.

C. While search warrants may be required in certain situations, the act of collecting physical evidence at a crime scene does not necessarily involve obtaining a search warrant.

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If 27.0 g of NaOH is added to 0.650 L of 1.00 M Cu(NO₃) ₂, how many grams of Cu(OH) ₂ will be formed in the following precipitation reaction? 2 NaOH(aq) + Cu(NO₃) ₂(aq) → Cu(OH) ₂ (s) + 2 NaNO₃(aq)

Answers

The precipitation reaction will produce 26.2 grams of Cu(OH)₂ .

To determine the grams of Cu(OH)₂ formed in the precipitation reaction, we need to use stoichiometry and the given quantities. The balanced equation tells us that 2 moles of NaOH react with 1 mole of Cu(NO₃)₂ to produce 1 mole of Cu(OH)₂.

First, we need to convert the given mass of NaOH to moles.

The molar mass of NaOH is

22.99 g/mol + 16.00 g/mol + 1.01 g/mol = 39.0 g/mol.

So, 27.0 g of NaOH is equal to 27.0 g / 39.0 g/mol = 0.692 moles.

Since the molarity (M) of Cu(NO₃)₂ is given as 1.00 M and the volume (V) is given as 0.650 L,

we can calculate the number of moles of Cu(NO₃)₂ as

1.00 mol/L × 0.650 L = 0.650 moles.

According to the stoichiometry of the reaction, 2 moles of NaOH react with 1 mole of Cu(NO₃)₂ to form 1 mole of Cu(OH)₂. Therefore, the moles of Cu(OH)₂ formed will be half the number of moles of Cu(NO₃)₂ used, which is 0.650 moles / 2 = 0.325 moles.

Finally, we can convert the moles of Cu(OH)₂ to grams using its molar mass.

The molar mass of Cu(OH)₂ is

63.55 g/mol + 16.00 g/mol + 1.01 g/mol = 80.6 g/mol.

Thus, the mass of Cu(OH)₂ formed will be

0.325 moles × 80.6 g/mol = 26.2 grams.

In summary, 26.2 grams of Cu(OH)₂ will be formed in the precipitation reaction.

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