Answer:
When we combine oxygen, and iron rust is produce.
Explanation:
The iron reacts with water and oxygen to form hydrated iron(III) oxide, which we see as rust. Iron and steel rust when they come into contact with water and oxygen – both are needed for rusting to occur.
Which of the following items represents a chemical change?
melting
evaporation
freezing
burning
For the reaction:
H₂O(1)→ H₂O(g)
ΔΗ = 44 kJ
How much heat is required when 9.0 g of H₂O is used?
1mol H_2O requires 44kJ heat
Moles of water
Given mass/Molar mass9/181/20.5molHeat required
0.5(44)22kJAs per the reaction given
Moles of H_2O=1
∆H=44kJMoles of water in 9g
Given mass/Molar mass9g/18g/mol0.5mol∆H
44(0.5)22KJUse the reaction and bond information to answer the question. H2 CO2 → CH2O2 Reactant bond energies: H–H is 432 kJ/mol, C=O is 799 kJ/mol Product bond energies: C–H is 413 kJ/mol, C=O is 745 kJ/mol, C–O is 358 kJ/mol, O–H is 467 kJ/mol How much energy must this system absorb before the reaction can begin?.
345678990098765435779999999999999999995699999
The bright coloring of the skin of this poison dart frog announces, "Don't eat me! My
skin is poisonous."
This is an example of an adaptation that meets the challenge of...
maintaining structure
reproduction.
getting and using energy
when energy is transferred does it increase or decrease
Answer:
About energy transfers:
Explanation:
When there is an energy transfer energy is neither created, nor destroyed. This means when that when one energy store decreases, one or more others must increase.
okay so if i fail the first time do i repeat the class? or can my teacher still pass me even if i pass the class but fail the test?
Answer:
It depends on what type of test your speaking of, is it a state exam?
If you are passing a class and fail a test you will still pass. If you fail a class you do not need to take it again if you don't want to but you would have to take another class instead.
PLEASE HELP!!!!!!!
In an experiment, the molar mass of the compound was determined to be 118.084 g/mol. What is the molecular formula of the compound?
Succinic acid most probably
C_4H_6O_4Lets see why?
The molar mass is given as 118.084g/mol
Decimal next place i.e 10th place contains 0 means it has OH bonds in most of the cases.
So it's a hydrocarbon and more closely an alcohol or aldehyde
Let's verify
4(12)+6(1)+16(4)64+48+670+58118g/molApproximately equal
The image shows a model of a nuclear reaction. Which objects could hit other atoms, producing a chain reaction?
The objects that could hit the atoms in the model shown are neutrons.
What is a chain reaction?A chain reaction is a reaction that is able to sustain itself. In this case, when the neutrons collide with the fissile nucleus, more neutrons are produced which collides with more fissile nuclei thereby sustaining the reaction.
Thus, the objects that could hit the atoms in the model shown are neutrons.
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Which are stronger, ionic bonds or covalent bonds?
Answer:
ionic bonds
Explanation:
ionic bonds result from the mutual attraction between oppositely charged ions. They tend to be stronger than covalent bonds due to the coulombic attraction between ions of opposite charges.
A solid, whose original weight was 8.492 grams, was dissolved in water. The
water solution was evaporated down to a small volume, then allowed to sit in a lab
drawer for a week. The resulting weight of the recovered solid was 9.045 grams.
a) Calculate the perfect recovery of the solid ._____
b) Give at least one reason why the percent recovery was greater than 100.0%
Answer:
See below
Explanation:
9.045/8.492 * 100% = 106.5%
There was other solids already dissolved in the water, or dust or other contaminants got into the water. ....or the measurement was incorrect. (like maybe the solid was still wet?)
Answer:
dfgdsgdffgfddffg
Explanation:
dfggffgdgdf
What does each star on the map represent?
O location of an epicenter
O location of a focus
O location of a seismograph
O location of a wave
Each star on the map represents location of an epicenter. Thus, the correct answer is Option A.
What is an epicentre on the map?Epicenter is defined as the point directly at the position on the Earth's surface, where the earthquake started. These are represented by the stars on the map.
Scientists use triangulation to find the epicenter of an earthquake.
When seismic data is collected from at least three different locations, it can be used to determine the epicenter by where it intersects.
Every earthquake is recorded on numerous seismographs located in different directions.
Thus, the correct answer is Option A.
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Answer: C. location of a seismograph
Explanation:
Determine the mass of hydrogen gas collected in a container if the gas occupies
44.8 L at STP.
Answer:
Hope this helps kinda got confused mid way
Explanation:
So the hydrogen sulphide is H2S for the molecular formula. Then the mass of hydrogen sulphide would be 1×2+32= 34g/mol At STP.
How many moles of a gas can be contained in a 1600-cm° flask at 25°C and 75 kPa?
Volume=1600cm³=1.6dm³=1.6L
Temperature=25°C=273+25=298K
Pressure=75000Pa
Now
Apply ideal gas equation
PV=nRTn=PV/RTn=75000(1.6)/8.314(298)n=48.43molThe number of moles needed is
n=48.43mol.
Calculations
Given the values of the volume and temperature, we would convert them to the required units.
Volume=1600cm³=1.6dm³=1.6L
Temperature=25°C=273+25=298K
Pressure=75000Pa
We would use the ideal gas equation
PV=nRT
n=PV/RT
n=75000(1.6)/8.314(298)
n=48.43mol
Explain how the period and group trends in atomic radii are related to electron configuration
7. Write the equation for the positron emission of barium-127.
The reaction is given by
[tex]\\ \rm\Rrightarrow {}^{127}_{56}Ba\longrightarrow {}^{0}_{+1}\beta+{}^{127}_{55}Cs[/tex]
Barium goes underneath beta decay to form Ceaseum
Cs is very mellable elementIt can melt on your hand[tex]\sf {}^{127}_{56}Ba\longrightarrow {}^0_{1}\beta+{}^{127}_{55}Cs[/tex]
Remember
Radioactive decays are first order reactionsThe rate constant doesn't depend upon initial concentrationIt's never ending reactionGiven that this reaction is exothermic, what direction will the equilibrium shift when the temperature of the reaction is decreased? 3H₂(g) + N₂(g) ⇔ 2NH₃(g)
A. Left (towards the reactants)
B. Right (towards the products)
C. No Shift
Equilibrium will shift towards the products when temperature is decreased in an exothermic reaction of the formation of ammonia.
What is an exothermic reaction?An exothermic reaction is a reaction in which heat content of the reactants is greater than the heat content of product.
In an exothermic reaction, heat is given off.
For an exothermic reaction in equilibrium, increasing temperature shifts equilibrium to the towards the left, towards the reactants.
On the other, equilibrium will shift towards the products when temperature is decreased.
Therefore, equilibrium will shift towards the products when temperature is decreased in the reaction of the formation of ammonia.
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Use Boyle's Law to interpret the following problem and then select the correct answer below.
A 1 L compressed tank is filled with Hydrogen gas and has a pressure of 100kPa. If all of the Hydrogen gas is removed from the tank and pumped into a 250mL tank what happens to the pressure?
Question 1 options:
The pressure in the 1 L tank increases.
None of the above.
The pressure in the 250mL tank increases.
All of the above.
The pressure in the 250 mL tank decreases.
The pressure of the compressed tank that was initially filled with hydrogen gas and has a pressure of 100kPa is pressure in the 250mL tank increases.
What is Boyle's law?Boyle's law states that the observation that the pressure of an ideal gas is inversely proportional to its volume at constant temperature.
According to this question, a 1 L compressed tank is filled with hydrogen gas and has a pressure of 100kPa.
If all of the hydrogen gas is removed from the tank and pumped into a 250mL tank, which is smaller in volume, the pressure in the 250mL tank increases.
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The number of moles of Cr deposited by passing 1,5 F electricity in following reaction Cr+3e–– ›cr is
The number of moles of Cr deposited by 1.5 F of electricity is 0.5 moles
What is electrolysis?The term electrolysis has to do with thee deposition of a solid when a direct current is passed through its solution.
Given the reaction; Cr3+(aq) + 3e ––›Cr(s)
If 3F of electricity is required to deposit 1 mole of Cr
1.5F of electricity is required to deposit 1.5F * 1 mole/3F
= 0.5 moles
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What is the pH of a solution that contains 0.0011 moles of KOH in 393 mL of solution?
The pH of a solution that contains 0.0011 moles of KOH in 393 mL of solution is 2.56. Details about pH can be found below.
How to calculate pH?The pH of a solution can be calculated using the following expression:
pH = - log [H3O+]
However, the hydrogen concentration of the KOH solution can be calculated as follows:
concentration = 0.0011 mol ÷ 0.393 L
concentration = 2.798 × 10-³M
The pH of KOH = - log [2.798 × 10-³M]
pH = 2.56
Therefore, the pH of a solution that contains 0.0011 moles of KOH in 393 mL of solution is 2.56.
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Why we use cotton cloth to mop the floor?
Answer:
because cotton have a good absorbing quality and can absorb water more which is used to mop the floor
Explanation:
Which of the following best describes physical science?
O A.
the study of motion
the study of matter and energy
the study of Earth's structure and processes
the study of reactions
the study of living things
OB.
O C.
OD.
OE.
The study of matter and energy best describes physical science. Hence, option B is correct.
What is physical science?Physical science is the study of the inorganic world.
Physics is a branch of science that studies matter and its motion through space and time, along with related concepts such as energy and force. Physics is one of the "fundamental sciences" because of the other natural sciences (like biology, geology etc.)
Thus the study of matter and energy best describes physical science. Hence, option B is correct.
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A The weak base ionization constant (Kb) for CH3NH2 is equal to: B [CH3NH3+][OH-] [CH3NH₂] [CH3NH3 +][OH [CH3NH2][N2 O]
The weak base ionization constant (Kb) for [tex]CH_3NH_2[/tex] is equal to
[tex]Kb = [CH_3NH^{3+}] [OH^-] / [CH_3NH_2][/tex]
What is Kb?Kb is the base dissociation constant.
The expression for the equilibrium constant, Kb is simply the ratio of the concentration of the products raised to their coefficient to the concentration of the reactants raised to their coefficient.
[tex]CH_3NH_2(aq) + H_2O(l)[/tex] → [tex]CH_3NH^{3+}(aq) + OH^- (aq)[/tex]
Thus, the expression for the equilibrium constant, Kb fo the above reaction can be written as follow:
[tex]Kb = [CH_3NH^{3+}] [OH^-] / [CH_3NH_2][/tex]
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What is the pH of a solution with a pOH of 10?
The pH of the solution is 4.
What is pH value ?pH value is the measure of the acidity and basicity of a solution.
It measures the [H+] ion liberated by an acid when dissolved in a solution.
It has a range of 0 to 14 , where 0 to 6.9 indicates acidity , 7 represents neutral solution , More than 7 up to 14 indicates alkaline solutions.
pH value is also used to predict the completion of a reaction .
It is given in the question that
The value of pOH = 10
pH = ?
It is known that the sum of pH and pOH is equal to 14.
pH + pOH = 14
pH + 10 = 14
pH = 4
Therefore the pH of the solution is 4.
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What is the molecular weight of one mole of H₂CO3?
Answer:
The molecular weight 62,03 g/mol
Calculate the solubility of Ca(OH)2 in a 0.469M CaCl2 solution at 31°C, given that the Ksp of Ca(OH)2 is 4.96 x 10-6 at that temperature. Give your answer in milliMolar units 2.927 mM 1.626 mM 2.764 mM 1.382 mM 1.463 mM 3.252 mM
The solubility of Ca(OH)2 in a 0.469M CaCl2 solution at 31°C, at given Ksp of Ca(OH)2 is determined as 1.626 mM.
Dissociation reaction of Ca(OH)2
The dissociation reaction of Ca(OH)2 is given as follows;
Ca(OH)₂ ⇄ Ca²⁺ + 2OH⁻¹
x 2x
Concentration of Ca²⁺ = 0.469 M
Ksp = [x][2x]²
ksp = (0.469)(2x²)
ksp = 4(0.469)x²
ksp = 1.876x²
4.96 x 10⁻⁶ = 1.876x²
x² = (4.96 x 10⁻⁶)/(1.876)
x² = 2.643 x 10⁻⁶
x = √(2.643 x 10⁻⁶)
x = 1.626 x 10⁻³ M
x = 1.626 mM
Thus, the solubility of Ca(OH)2 in a 0.469M CaCl2 solution at 31°C, at given Ksp of Ca(OH)2 is determined as 1.626 mM.
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Which of the following is a heterogeneous mixture?
a) salt water
b) soil
c) steel
d) air
Answer:
b) soil
heterogenous means you can pick out individual bits.
What is the heat of reaction into kJ?
H₂(g)+Br₂(g)➝2HBr(g)
see the attached file!!!
Based on the following reaction, how much water is produced when oxygen react with 1 mole of C₂H8?
C₂H8 (g) + 40₂ (g) →2CO2 (g) + 4H₂O(g)
Answer:
4 moles
Explanation:
For every mole of deuteriomethane consumed, 4 moles of water are produced.
So, the answer is 4 moles.
For the reaction
2A(g)+2B(g)+C(g)⟶3G(g)+4F(g)
the initial rate data in the table was collected, where [A]0 , [B]0 , and [C]0 are the initial concentrations of A , B , and C , respectively.
Experiment [A]0 (mmol⋅L−1) [B]0 (mmol⋅L−1) [C]0 (mmol⋅L−1) Initial rate (mmol⋅L−1⋅s−1)
1 11.0. 200.0 220.0 8.80
2 22.0 200.0 165.0 17.6
3 22.0 400.0 55.0 70.4
4 11.0 200.0 110.0 8.80
Reactant A is first order reactant, Reactant B is second order reactant, and Reactant C is zero order reactant...
1. What is the overall order of the reaction ______ ???
2. Write the rate law for the reaction where is the rate constant. Rate = k___???
3. Calculate the rate constant, , and identify its units. K = ____?????
4. Determine the initial rate of the reaction when [A]0=4.87 mmol⋅L−1 , [B]0=0.184 mmol⋅L−1 , and [C]0=12.0 mmol⋅L−1 . Initial Rate = _______ mmol⋅L−1⋅s−1 ??????
The overall order of the reaction is 3 and the rate law for the reaction is rate = [A]^n [B]^m [C]^l
How to find the Order of Reaction?
1) The order of reactant A is first order reactant because a first-order reaction can be defined as a chemical reaction in which the reaction rate is linearly dependent on the concentration of only one reactant.
The order of reactant B is second order reactant because a second order reaction is a type of chemical reaction that depends on the concentrations of one-second order reactant or two first-order reactants.
Thus, the overall order of the reaction is 3.
2) The rate law in this reaction is;
rate = [A]^n [B]^m [C]^l
But in this question, since the reactant C is zero order, then it will be simplified to; rate = k[A][B]² .
3) When we plug in the initial concentrations of A and B, we will get the rate constant of the problem which is k = 20.
4) The initial rate when [A]0=4.87 mmol⋅L−1 , [B]0=0.184 mmol⋅L−1 , and [C]0=12.0 mmol⋅L−1 is;
Rate = 20 * 4.87 * 0.184²
Rate = 3.3
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Write the complete chemical equations for production of pentanol from pentene
Answer:
hope this helped :( got this from my friend a long time ago but still not sure if it's really correct this