Answer:
1. 306,000: three significant figures because the last three zeros are not preceded by a decimal point.
2. 0.0073: two significant figures because the the leftmost zeros are not significant.
3. 39.9999: six significant figures because all these numbers are nonzero digits.
4. 25.00: four significant figures because right-handed zeros, after a decimal point, are significant.
5. 40,000,021: eight significant figures because intermediate zeros are significant.
6. 45,250.0: six significant figures because al the zeros are to the right of the nonzero digits.
7. 0.00011: two significant figures as well as #2.
8. 420.030700: nine significant figures because all the zeros are to the right of the first nonzero digits and after the decimal point.
Explanation:
Hello there!
In this case, by considering the given numbers, we can proceed as follows, by keeping in mind the rules for assigning significant figures:
1. 306,000: three significant figures because the last three zeros are not preceded by a decimal point.
2. 0.0073: two significant figures because the the leftmost zeros are not significant.
3. 39.9999: six significant figures because all these numbers are nonzero digits.
4. 25.00: four significant figures because right-handed zeros, after a decimal point, are significant.
5. 40,000,021: eight significant figures because intermediate zeros are significant.
6. 45,250.0: six significant figures because al the zeros are to the right of the nonzero digits.
7. 0.00011: two significant figures as well as #2.
8. 420.030700: nine significant figures because all the zeros are to the right of the first nonzero digits and after the decimal point.
Regards!
A sample of Kr gas is observed to effuse through a porous barrier in 3.79 minutes. Under the same conditions, the same number of moles of an unknown gas requires 2.66 minutes to effuse through the same barrier. The molar mass of the unknown gas is________ g/mol.
Answer:
[tex]M'=41.3g/mol[/tex]
Explanation:
From the question we are told that:
Time Through first barrier [tex]T_1=3.79min[/tex]
Time Through second barrier [tex]T_2=2.66min[/tex]
Generally the Grahams Law equation for time of diffusion is mathematically given by
[tex]T=K\sqrt{M}[/tex]
Where
M=Mass Number of Kr
[tex]M=83.8[/tex]
Therefore
[tex]{T}{\sqrt{M}={T}{\sqrt{M'}[/tex]
[tex]{3.79}{\sqrt{83.8}={2.66}{\sqrt{M'}[/tex]
[tex]M'=0.645[/tex]
[tex]M'=41.3g/mol[/tex]
propose a synthetic route for the synthesis of a named alkanal starting with ethyl formate and grignard reagent.
Answer:
See explanation and image attached
Explanation:
A Grignard reagent is an alkyl magnesium halide. If it reacts with ethyl formate, an intermediate is formed as shown.
This intermediate can undergo water hydrolysis to form a diol, ethanol and MgBrOH.
Oxidation of the diol obtained now yields the corresponding alkanal which in this case is ethanal.
The scheme of the reaction is shown in the image attached to this answer.
Energy is just like water, cycles through ecosystems.
True or false?
Answer:
true
Explanation:
I think
Rank the species below in order of decreasing leaving group capabilities in SN2 reactions (best leaving group to worst).
A. H2N-
B. CH3O-
C. C6H5SO3-
D. H2O
1. Best
2. Worst
Answer:
H2O> C6H5SO3- > CH3O- > H2N-
Explanation:
SN2 reaction is a reaction in which there is a synchronous departure of the leaving group and attachment of the incoming nucleophile in the transition state. Hence, an SN2 reaction passes through a single transition state. It is a bimolecular reaction.
A good leaving groups must be stable on its own. Usually, weak bases and neutral species are good leaving groups.
The order decreasing leaving group capabilities in SN2 reactions for the species listed in the question is;
H2O>C6H5SO3-> CH3O-> H2N-
Hence H2O is the best leaving group while H2N- is the worst leaving group.
The ranking from the best-leaving group to worst leaving group in SN2 reactions would be D. H₂O (water), C. C6H5SO3- (phenylsulfonate), B. CH₃O- (methoxide), A. H₂N- (amide).
In SN₂ reactions, leaving group capabilities are determined by the ability of the group to accept electrons and leave the molecule. The better the leaving group, the easier it is for it to leave the molecule. Based on this,
Water is a weak base and a good leaving group in SN2 reactions.
Phenylsulfonate is also a good leaving group, but it is slightly weaker than water.
Methoxide is a weaker base and leaving group compared to water and phenylsulfonate.
Amide is the weakest base and leaving group among the provided species.
To learn more about the SN₂ reactions, follow the link:
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True or false? An organism may play more than one role in a food web
Answer:
true
Explanation:
because an organism have many roles in food web
The table below provides data about a gas sample.
Volume
1.0 L
Pressure
303.9 kPa
Temperature
323 K
Which of the following can be determined using the data?
A the chemical composition of the gas
B. the condensation temperature of the gas
C. the distance between gas molecules in the sample
D. the number of gas molecules in the sample
Answer:
the number of gas molecules in the sample
Who was the first person to suggest the existence of atoms?
Answer:
Democritus first introduced the idea of the atom almost 2500 years ago.
Answer:
B. Democritus
Explanation:
Refer to your completed Table 1d of the recitation guide of ionic compound naming rules to determine whether this statement is true or false. A Roman numeral in a compound name tells you how many of that ion appear in the formula. Select one: True False
Answer:
False
Explanation:
Roman numerals are seen in the names of several compounds. They often appear immediately after the name of central atom in the molecule.
These Roman numerals are used to depict the oxidation state of the central atom in the molecule and not to show how many of that ion appear in the formula.
For instance, in carbon IV oxide, the Roman numeral IV shows that the central atom in the compound-carbon is in the +4 oxidation state.
Which aqueous solution has the highest vapor pressure at 25ºC? 15.0g of sucrose (C12H22O11) in 100.0mL of water
The question is incomplete, the complete question is;
Which aqueous solution has the highest vapor pressure at 25ºC?
15.0g of glucose (C6H12O6) in 100.0mL of water
25.0g of glucose (C6H12O6) in 100.0mL of water
15.0g of sucrose (C12H22O11) in 100.0mL of water
25.0g of sucrose (C12H22O11) in 100.0mL of water
Answer:
15.0g of sucrose (C12H22O11) in 100.0mL of water
Explanation:
The vapor pressure of a substance is a colligative property. Colligative properties are the properties of a substance that depend on the amount of solute present.
Since vapour pressure is a colligative property, we have to look out for the solution that has the lowest number of moles because as more solute is dissolved in the solvent, the vapor pressure of the solvent decreases.
Hence, 15.0g of sucrose (C12H22O11) in 100.0mL of water has the lowest number of moles in solution thus it is expected to exhibit the highest vapour pressure.
HELP PLEASE HURRY!!!
You have 12.51 grams of C2H6, how many moles do you have?
Answer:
How many grams C2H6 in 1 mol? The answer is 30.06904. We assume you are converting between grams C2H6 and mole. You can view more details on each measurement unit
"A space shuttle travels around the Earth at a constant speed of 28000 kilometers per hour. If it takes 90 minutes to complete one orbit, how far is its journey around Earth?
"
Answer:
42000km
Explanation:
Average Speed (v) can be calculated using the formula as follows:
Average speed = distance (d) ÷ time (t)
According to this question, a space shuttle travels around the Earth at a constant speed of 28000 km/hr in 90 minutes.
Since 60 minutes = 1 hr
90 minutes = 90/60
= 3/2 or 1.5hours.
Using speed = distance/time
Distance (km) = speed × time
Distance = 28000 km/hr × 1.5hr
Distance = 42000km
The most intense line in the emission spectrum for sodium appears at a wavelength of 589 nm. What color would you expect to observe when a solution that contains sodium ions is heated strongly in the flame of a Bunsen burner
Answer:
The most intense line in the emission spectrum for sodium appears at a wavelength of 589 nm.
What color would you expect to observe when a solution that contains sodium ions is heated strongly in the flame of a Bunsen burner?
Explanation:
Put a clean wire loop in a solid sample of the compound containing sodium ions, then keep it on the blue flame of the Bunsen burner.
The color of sodium ions in the Bunsen burner shows charactrestic yellow color.
For the reaction...
N2 + O2 <=> 2NO: AH = +182 kJ mol-1.
If the temperature is increased the equilibrium position will shift
Your answer:
a) to the left
b) to the right
c) to the left and right
d) neither left nor
right
Answer:
B
Explanation:
AH is positive so the forward reaction is endothermic. Thus, increasing temperature would cause equilibrium to shift to the right as endothermic reaction favors higher temperature. This increases the yield of NO.
The table shows the recipe and the available ingredients for making the maximum possible number of sandwiches.
Making Sandwiches
Recipe for One Sandwich:
2 cheese slices, 1 ham slice, 2 bread slices
Ingredients Available:
12 cheese slices, 10 ham slices, 12 bread slices
If the ingredients represent reactants of a chemical reaction, which of the following represents the leftover reactant?
A. 2 ham slices
B. 4 ham slices
C. 2 cheese slices
D. 4 cheese slices
Answer:
B. 4 ham slices
Explanation:
A chemical reaction involves one or more substances known as reactants combining chemically to give one or more substances known as products.
Reactants in chemical reactions combine in definite mole or mass ratios to give products. Therefore, when one substance is present in excess of what is required to combine with another to form products, that substance is known as the excess reagent. The other substance which is present in a smaller amount and which when used up, the reaction stops is known as the limiting reagent.
From the illustration of the sandwiches in the question, the recipe for one sandwich represents the chemical equation of a reaction. The equation form is given below:
2 cheese slices + 1 ham slice + 2 bread slices ---> 1 sandwich
The ratio of the reactant is 2 : 1 : 2
From the available ingredients, 12 cheese slices, 10 ham slices, 12 bread slices.
12 cheese slices will require 6 ham slices and 12 bread slices to produce 6 sandwiches.
However, since there are 10 ham slices, 4 ham slices will be left over unused. This is the excess or leftover reactant.
Answer:
B. 4 ham slices
Explanation:
Got it right on the test
What are the laws and calculations governing gas behavior?
Answer:
Laws governing gas behavior.
Explanation:
Boyle's law:
It relates the pressure and volume of an ideal gas at a constant temperature.
According to this law:
"The volume of a fixed amount of gas at constant temperature is inversely proportional to its pressure".
[tex]P \alpha V[/tex].
Charle's law:
It relates the volume and absolute temperature of an ideal gas at a constant pressure.
According to this law:
"The volume of a fixed amount of gas at constant pressure is directly proportional to its absolute temperature".
[tex]V \alpha T[/tex].
Avogadro's law:
According to this law:
equal volumes of all gases under the same conditions of temperature and pressure contain, an equal number of moles.
[tex]V \alpha n[/tex].
Ideal gas equation:
By combining all the above-stated gas laws, this equation is formed as shown below:
[tex]V \alpha \frac{nT}{P} \\=> V= R. nT/ P\\=>PV=nRT[/tex]
R is called universal gas constant.
It has a value of 0.0821L.atm.mol-1.K-1.
Answer:
Boyle's law, Charle's law, Guy Lussac's law and Avogadro's law
Explanation:
All the gases behaves similarly when the environment conditions are normal. But when the physical condition changes like when the pressure, volume or temperature changes, the gas behaves differently and shows a deviation.
The number of gas laws are :
Boyle's Law
Boyle's law states that when the temperature remaining constant, the pressure of the gas varies inversely to the volume of the gas.
i.e. [tex]P \propto \frac{1}{V}[/tex]
Charle' law
Charle's law states that when pressure is constant, the temperature of a gas is directly proportional to the volume.
i.e. , [tex]$T \propto V$[/tex]
Gay Lussac's law
Gay - Lussa law states the volume and the mass of the pressure of the gas is directly proportional to the temperature of the gas.
i.e. P.T = constant
Avogadro's law
It states that under the conditions of same pressure as well as temperatures, the gases having equal volumes will have same numbers of molecules.
i.e. [tex]\frac{V_1}{n_1}=\frac{V_2}{n_2}[/tex] = constant
True or False
Helium belongs to Noble Metals
Answer:
This answer is "True"
What are the free moving, charged particles in a molten mixture of aluminium oxide and cryolite?
Answer:
Ions.
Explanation:
Ions are the free moving, charged particles in a molten mixture of aluminum oxide and cryolite because the liquid state loosely held the molecules and the the molecules can easily move from one place to another. These ions helps in the conduction of electricity in the solution due to its free movement so we can say that ions are the charge particles that moves freely in the mixture of aluminum oxide and cryolite.
The free moving, charged particles in a molten mixture of aluminium oxide
and cryolite are known as Ions.
Ions are referred to an atom or compound which possesses an electrical
charge.The charge could be positive or negative and the positive ions are
called cations while the negative ions are referred to an anions.
Ions are usually free moving, take part in chemical reactions and help to
conduct electricity as a result of them being transferred from one point to
another.
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3CaCl2 + 2AlF3 --> 3CaF2 + 2AlCl3 3CaCl2 + 2AlF3 --> 3CaF2 + 2AlCl3 How many grams of CaF2 will form from 36.5 grams of AlF3?
Answer:
32.1 g
Explanation:
3CaCl₂ + 2AlF₃ → 3CaF₂ + 2AlCl₃
First we convert 36.5 g of AlF₃ into moles, using its molar mass:
36.5 g ÷ 133.34 g/mol = 0.274 mol AlF₃
Then we convert 0.274 moles of AlF₃ into moles of CaF₂, using the stoichiometric coefficients of the reaction:
0.274 mol AlF₃ * [tex]\frac{3molCaF_2}{2molAlF_3}[/tex] = 0.411 mol CaF₂
Finally we convert 0.411 moles of CaF₂ into grams, using its molar mass:
0.411 mol * 78.07 g/mol = 32.1 g
heating curve shows temperature verses energy gain. Which parts of the curve represent a gain in potential energy?
100
Temperature (°C)
0
Increasing Energy
Answer:
Those two horizontal lines.
Explanation:
Hello there!
In this case, when focusing on these heating curves, it is important to say they tend to have two constant-temperature sections and three variable-temperature sections. Thus, from lower to higher temperature, the first constant-temperature section corresponds to melting and the second one vaporization, whereas the three variable-temperature sections correspond to the heating of the solid until melting, the liquid until vaporization and the gas until the critical point.
In such a way, we infer that the boxes referred to constant temperature are referred to a gain in potential energy, that is, the two horizontal lines.
Regards!
Answer: My sacrifica has been made.
Explanation:
is Decanitrogen tetroxide Ionic or Molecular
Answer:
Decanitrogen is molecular
Explanation:
Answer:
Dec a nitrogen is Molecular
Explanation:
hey mate i hope it will help you...!
What is the overall charge of an ion that has 31 protons, 36 electrons, and 30 neutrons?
Answer:
(d) the ion with 24 electrons, 30 neutrons, and a 3+ charge ... (b) the ion with 36 electrons, 35 protons, and 45 neutrons.
What the correct answer
Answer:
[Ar] 4s²3d³
Explanation:
Vanadium has atomic number of 23. The electronic configuration of vanadium can be written as:
V (23) => 1s² 2s²2p⁶ 3s²3p⁶ 4s²3d³
NOTE: After the 18th electron, 4s will be filled before 3d.
We can also write the electronic configuration of an element in its condensed form by writing the symbol of the noble before the desired element in a squared bracket followed by the remaining electrons to complete the electronic configuration of the element.
The electronic configuration of vanadium in its condensed form is given below:
The noble gas before vanadium is Argon (Ar) with atomic number of 18. Thus, the electronic configuration of vanadium becomes:
V (23) => [Ar] 4s²3d³
How do I balance this?
_CuC12 + _NaNO3 → _CU(NO3)2 + _ NaC1
[tex]CuCl_2+2NaNO_3 \rightarrow Cu(NO_3)_2 + 2NaCl[/tex]
calculate the mass in 4.05*10^22 molecules of calcium phosphate
Answer:
m = 20.9 g.
Explanation:
Hello there!
In this case, according to the given information, it turns out possible for us to solve this problem by recalling both the Avogadro's number for the calculation of the moles in the given molecules of calcium phosphate and the molar mass of this compound in order to secondly calculate the mass as shown on the following setup:
[tex]m=4.05x10^{22}molecules*\frac{1mol}{6.022x10^{23}}*\frac{310.18g}{1mol}\\\\m=20.9g[/tex]
Regards!
Which of the following natural hazards occur for a long period of time?
tornado
earthquake
drought
thunderstorm
Answer:
drought
Explanation:
droughts are long periods without water
which of the following illustrates a reversible change a cooking corn be rusting c frying egg and the boiling water
Calculate the number of moles
309 grams of (SF)4 = how many moles of (SF)4
Answer:
2.85 mol
Explanation:
Step 1: Given data
Mass of sulfur tetrafluoride (SF₄): 309 g
Step 2: Calculate the number of moles corresponding to 309 g of sulfur tetrafluoride
To convert mass to moles we need a conversion factor: the molar mass. The molar mass of SF₄ is 108.07 g/mol.
309 g × 1 mol/108.07 g = 2.85 mol
A man of 450 N covers an area of 0.0015m2 while standing on his feet.calculate the pressure exerted by him on the ground.
Answer:
3×10⁵ N/m²
Explanation:
From the question given above, the following data were obtained:
Force (F) = 450 N
Area (A) = 0.0015 m²
Pressure (P) =?
Pressure is simply defined as the force per unit area. Mathematically, it is expressed as:
Pressure (P) = Force (F) / Area (A)
P = F/A
With the above formula, we can obtain the pressure exerted by the man on the ground. This can be obtained as follow:
Force (F) = 450 N
Area (A) = 0.0015 m²
Pressure (P) =?
P = F/A
P = 450 /0.0015
P = 3×10⁵ N/m²
Thus, the pressure exerted by the man on the ground is 3×10⁵ N/m².
Name an alkene that would yield the alcohol above on hydration. (Submit a single name even if there is more than one correct answer. Ignore double bond stereochemistry.) Name: fill in the blank 75a878faaf91fe7_1 2,3-Dimethylpentane . Specify whether you would use hydroboration/oxidation or oxymercuration.
Answer:
Enzyme ? ...............
describe how you would test your indicator to check that it works
Answer:
If the colour of the indicator changes blue when a base is there and when it changes to red or pink or scarlet when it is acid. Then we can say that the indicator is working