Gas Laws

Consider the reaction. 3Mg(s)+2H3PO4(aq)-Mg3(PO4)2(s)+3H2(g) Which statement is true at STP? (The atomic mass of Mg is 24.31 u.)

(3 X 24.31) g of Mg produce (3 X 22.4) L of H2 gas.

A tire at 21°C has a pressure of 0.82 atm. Its temperature decreases to -3.5°C. If there is no volume change in the tire, what is the pressure after the temperature change?

0.75 atm

A gas cylinder contains 2.0 mol of gas X and 6.0 mol of gas Y at a total pressure of 2.1 atm. What is the partial pressure of gas Y?

1.6 atm

What volume would 3.01•10^23 molecules of oxygen gas occupy at STP?

11.2 L

The molar mass of nitrogen (N2) is 28.02 g/mol. What is the mass, in grams, of 4.60 mol of N2?

129

Which gas occupies the highest volume at STP?

2 mol of H2

What is the molar volume of a gas at standard temperature and pressure?

22.4 L

Propane (C3H8), a fuel that is used in camp stoves, produces carbon dioxide (CO2) and water vapor (H2O) on combustion as follows. C3H8(g)+5O2(g)-3CO2(g)+4H2O(g) Given that the molar mass of H2O is 18.02 g/mol, how many liters of propane are required at STP to produce 75 g of H2O from this reaction?

23 L

What is the pressure of 0.540 mol of an ideal gas at 35.5 L and 223 K?

28.2 kPa

What is the volume of 0.200 mol of an ideal gas at 200. kPa and 400. K?

3.33 L

A balloon that had a volume of 3.50 L at 25.0°C is placed in a hot room at 40.0°C. If the pressure remains constant at 1.00 atm, what is the new volume of the balloon in the hot room?

3.68 L

Consider the equation. 2H2(g)+O2-2H2O(g) Which represents the correct mass-volume relationship at STP?

32.00 g of O2 react with an excess of H2 to produce (2x22.4) L of H2O.

Consider the reaction. CH4(g)+2O2(g)-CO2(g)+2H2O(g) How many grams of methane should be burned in an excess of oxygen at STP to obtain 5.6 L of carbon dioxide?

4.0 g

What is the volume of 2 mol of chlorine gas at STP?

44.8 L

According to the equation 2Na + 2H2O mc012-1.jpg 2NaOH+H2, what mass of Na is required to yield 22.4 L of H2 at STP? (The atomic mass of Na is 22.99 u.)

46.0 g

A chemist has 2.0 mol of methanol (CH3OH). The molar mass of methanol is 32.0 g/mol. What is the mass, in grams, of the sample?

64

Which law states that the volume and absolute temperature of a fixed quantity of gas are directly proportional under constant pressure conditions?

Charles's law

The chemical equation below shows the burning of magnesium (Mg) with oxygen (O2) to form magnesium oxide (MgO). 2Mg + O2 mc019-1.jpg 2MgO Niven wants to calculate the mass of MgO that is produced by the burning of 28.0 g of Mg. What is the first step in Niven's calculation?

Convert grams of Mg to moles.

The absolute temperature of a gas is increased four times while maintaining a constant volume. What happens to the pressure of the gas?

It increases by a factor of four.

Consider a balloon that has a volume V. It contains n moles of gas, it has an internal pressure of P, and its temperature is T. If the balloon is heated to a temperature of 15.5T while it is placed under a high pressure of 15.5P, how does the volume of the balloon change?

It stays the same.

The volume of a gas decreases to half of its original volume, but the gas maintains the same number of moles and temperature. According to the ideal gas law, what will most likely happen to the pressure?

It will double.

Magnesium chloride, MgCl2(s) reacts with water vapor to form magnesium oxide, MgO(s) and HCl(g). What is the balanced chemical equation for this reaction?

MgCl2(s) + H2O(g) - MgO(s) + 2HCl(g)

Nitrogen reacts with hydrogen to produce ammonia gas as follows. N2(g)+3H2(g)-2NH3(g) How many moles of nitrogen would react with excess hydrogen to produce 520 mL of ammonia?

NOT 0.024 mol NOT 0.0232 mol

Consider the reaction. Zn(s)+2HCl(aq)-ZnCl2(aq)+H2(g) Which statement is true at STP? (The atomic mass of Zn is 65.39 u.)

NOT 2 mol of HCl produce 1 L of H2 gas. NOT 1 L of HCl produces 1 mol of H2 gas.

Magnesium reacts with hydrochloric acid (HCl) as follows. Mg(s)+2HCl(aq)-MgCl2(aq)+H2(g) How many milliliters of hydrogen gas are produced by the reaction 0.020 mol of magnesium with excess of hydrochloric acid at STP?

NOT 448 mL

The gases listed are at standard temperature and pressure: · 1 mol of CO2 gas · 1 mol of N2 gas · 2 mol of O2 gas Which statement is correct?

The volumes of 1 mol of CO2 and 1 mol of N2 gases are the same.

Shana solves stoichiometry problems using the equation for the synthesis of water. 2H2(g)+O2(g)-2H2O(g) Which interpretation of the balanced equation would cause Shana to make a mistake?

Two grams of hydrogen react with one gram of oxygen to form two grams of water.

Which proportionality applies to Avogadro's law?

V oc n

Which proportionality shows the result of combining Avogadro's law with Boyle's law?

V oc n/p

Which equation agrees with the ideal gas law?

V1/T1=V2/T2

Which statement would be the most useful for deriving the ideal gas law?

Volume is directly proportional to the number of moles.

Under which conditions does the molar volume of a gas decrease?

at 273 K and at 2.0 atm

Consider the proportionality below. PV oc nT What does this best represent?

ideal gas law

What is used up in and stops a chemical reaction?

limiting reactant

Chandra wants to know how many moles are contained in 150.0 g CCl4 (carbon tetrachloride). What quantity of CCl4 should she use to make this conversion?

molar mass

Which quantity is held constant when working with Boyle's, Charles's, and Gay-Lussac's laws?

moles

The incomplete table below shows selected characteristics of gas laws. What are the variables in Gay-Lussac's law?

pressure and temperature

Consider the balanced equation. 2HCl + Mg mc031-1.jpg MgCl2 + H2 If 40.0 g of HCl react with an excess of magnesium metal, what is the theoretical yield of hydrogen?

1.11 g

Consider the reaction. C(s)+O2(g)-CO2(g) How many grams of carbon should be burned in an excess of oxygen at STP to obtain 2.21 L of carbon dioxide? 1.18 g

1.18 g

Which law is described by saying that when the pressure of a gas in a sealed container is cut in half, the gas will double in volume at a steady temperature?

Boyle's law

A gas has experienced a small increase in volume but has maintained the same pressure and number of moles. According to the ideal gas law, how has the temperature of the gas changed?

It has increased slightly.

Which equation represents the combined gas law?

P1V1/T1=P2V2/T2

The ideal gas constant, R has several different values that could be used. Which quantity causes these differences?

pressure

If two gases are present in a container, the total pressure in the container is equal to

the sum of the pressures that are exerted by each of the two gases.

Which correctly defines molar volume of an ideal gas?

the volume that is occupied by 1 mol of an ideal gas at STP, which is 22.4 L

The chemical equation below shows the decomposition of nitrogen triiodide (NI3) into nitrogen (N2) and iodine (I2). 2NI3 mc030-1.jpg N2 + 3I2 The molar mass of I2 is 253.80 g/mol, and the molar mass of NI3 is 394.71 g/mol. How many moles of I2 will form 3.58 g of NI3?

0.0136

The equation represents the combustion of sucrose. C12H22O11 + 12O2 mc007-1.jpg 12CO2 + 11H2O If there are 10.0 g of sucrose and 8.0 g of oxygen, how many moles of sucrose are available for this reaction?

0.029 mol

A container holds 6.4 moles of gas. Hydrogen gas makes up 25% of the total moles in the container. If the total pressure is 1.24 atm. What is the partial pressure of hydrogen?

0.31 atm

A scientist is examining a mixture of nitrogen, hydrogen, and ammonia. The individual pressures that are exerted by nitrogen and hydrogen are 0.26 atm and 0.28 atm, respectively. If the total pressure is 0.90 atm, what is the partial pressure of ammonia?

0.36 atm

Mercury(II) oxide (HgO) decomposes to form mercury (Hg) and oxygen (O2). The balanced chemical equation is shown below. 2HgO mc020-1.jpg 2Hg + O2 The molar mass of HgO is 216.59 g/mol. The molar mass of O2 is 32.00 g/mol. How many moles of HgO are needed to produce 250.0 g of O2?

15.63

Passing an electric current through a sample of water (H2O) can cause the water to decompose into hydrogen gas (H2) and oxygen gas (O2) according to the following equation. 2H2O mc026-1.jpg 2H2 + O2 The molar mass of H2O is 18.01 g/mol. The molar mass of O2 is 32.00 g/mol. What mass of H2O, in grams, must react to produce 50.00 g of O2?

56.28

Consider the reaction. N2(g)+3H2(g)-2NH3(g) How many grams of N2 are required to produce 100.0 L of NH3 at STP?

62.5 g

The electrolysis of water forms H2 and O2. 2H2O mc017-1.jpg 2H2 + O2 What is the percent yield of O2 if 10.2 g of O2 is produced from the decomposition of 17.0 g of H2O?

67.6%

What is the temperature of 0.80 mol of a gas stored in a 275 mL cylinder at 175 kPa?

7.2 K

Ammonia is produced by the following reaction. 3H2(g) + N2(g) mc005-1.jpg 2NH3(g) When 7.00 g of hydrogen react with 70.0 g of nitrogen, hydrogen is considered the limiting reactant because

7.5 mol of hydrogen would be needed to consume the available nitrogen.

Consider the balanced equation. CuSO4 + Zn mc016-1.jpg ZnSO4 + Cu If 200.0 g of copper(II) sulfate react with an excess of zinc metal, what is the theoretical yield of copper?

79.63 g

What is the percent yield of ferrous sulfide if the actual yield is 220.0 g and the theoretical yield is 275.6 g?

79.8%

The molar mass of hydrogen (H2) is 2.02 g/mol. A sample contains 4.00 mol of H2. What is the mass, in grams, of this sample?

8.08

When magnesium chloride reacts with water, 5.85 L HCl(g) is produced. molar mass of HCl = 36.5 g/mol molar mass of MgCl2 = 95.2 g/mol A. How many moles of HCl was produced? B. How many moles of MgCl2 reacted? C. What mass of MgCl2 reacted?

A. 0.261 moles of HCl B. 0.131 moles of MgCl2 C. 12.4 g MgCl2

Assume that 8.5 L of iodine gas (I2) are produced at STP according to the following balanced equation: 2KI(aq) + Cl2(g) → 2KCl(aq) + I2(g) A. How many moles of I2 are produced? B. How many moles of Cl2 are used? C. How many grams of Cl2 (g) are used?

A. 0.38 mol B. 0.38 mol C. 27 grams

3H2(g) + N2(g) → 2NH3(g) A. What volume of nitrogen is needed to produce 250.0L of ammonia gas at STP? B. What volume of hydrogen is needed to produce 2.50 mol NH3 at STP?

A. 125.0 L B. 84.0 L

Liquid carbon disulfide (CS2) reacts with 44.8 L O2 gas to produce the gases carbon dioxide (CO2) and sulfur dioxide (SO2). A. What is the mass of carbon dioxide produced? B. What is the mass of sulfur dioxide produced? C. When making the calculations, did you need to find the number of moles?

A. 29.3 g B. 85.4 g C. yes

Acetylene gas (C2H2) reacts with oxygen gas (O2) to produce carbon dioxide (CO2) and water vapor (H2O). A. How many liters of C2H2 are required to produce 75.0 L of CO2? B. What volume of H2O is produced? C. What volume of O2 is required? D. When making the calculations, did you need to find the number of moles?

A. 37.5 L B. 37.5 L C. 93.8 L D. no

The Haber process can be used to produce ammonia (NH3) from hydrogen gas (H2) and nitrogen gas (N2). The balanced equation for this process is shown below. 3H2 + N2 mc025-1.jpg 2NH3 The molar mass of NH3 is 17.03 g/mol. The molar mass of H2 is 2.0158 g/mol. In a particular reaction, 0.575 g of NH3 forms. What is the mass, in grams, of H2 that must have reacted, to the correct number of significant figures?

NOT 0.10209

Lakshmi has a sample of ammonium nitrate (NH4NO3) that has a mass of 40.10 g. She knows that the molar mass of NH4NO3 is 80.0432 g/mol. To the correct number of significant digits, how many moles of NH4NO3 does the sample contain?

NOT 0.500980

The chemical equation shows how ammonia reacts with sulfuric acid to produce ammonium sulfate. 2NH3(aq) + H2SO4(aq) mc012-1.jpg (NH4)2SO4(aq) How many grams of ammonium sulfate can be produced if 60.0 mol of sulfuric acid react with an excess of ammonia?

NOT 3,970 g

Decomposition of potassium chlorate (KClO3) produces potassium chloride (KCl) and pure oxygen (O2). The balanced equation for the reaction is as follows. 2KClO3(s)-2KClO(s)+3O2(g) What volume of oxygen gas is released at STP if 10.0 g of potassium chlorate is decomposed? (The molar mass of KClO3 is 122.55 g/mol.)

NOT 3.66 L

Consider the balanced chemical equation for the combustion of methane (CH4). CH4(g)+2O2(g)-CO2(g)+2H20(g) Given that the molar mass of CO2 is 44.01 g/mol, how many liters of oxygen is required at STP to produce 88.0 g of CO2 from this reaction?

NOT 44.8 L NOT 89.55 L

Consider the combustion reaction for acetylene. 2C2H2(l) + 5O2(g) mc001-1.jpg 4CO2(g) + 2H2O(g) If the acetylene tank contains 37.0 mol of C2H2 and the oxygen tank contains 81.0 mol of O2, what is the limiting reactant for this reaction?

NOT CO2

A student uses 0.0821 L• atm/mol • K as the value of the gas constant. What is most likely true about the variables in the ideal gas law?

NOT P has the units of liters • atmospheres, and T has the units of kelvin.

Avogadro's law and Charles's law describe a proportionality of the volume of a gas when the pressure is constant. Which describes the proportionality that allows these laws to be combined when describing a gas?

NOT Volume is inversely proportional to moles (Avogadro's law) and to temperature (Charles's law).

The incomplete table below shows selected characteristics of gas laws. Which constants would most likely be filled in the first row of the table?

NOT volume and temperature

Which equation is derived from the combined gas law?

V1/T1=V2/T2

Salicylic acid (C7H6O3) reacts with acetic anhydride (C4H6O3) to form acetylsalicylic acid (C9H8O4). 2C7H6O3(aq) + C4H6O3(aq) mc002-1.jpg 2C9H8O4(aq) + H2O(l) What is the limiting reactant if 70.0 g of C7H6O3 and 80.0 g of C4H6O3 react?

salicylic acid