# Solutions

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1. A sample of 6.9 moles of gas is placed in a container of volume of 30.4 L. What is the pressure of the gas in torr if the gas is at 62oC? P = 4744 torr

What would be the volume of this gas if placed at STP? V = 154.6 L

2. A 2.1 L flask contains 4.65 g of gas at 1 atm and 27oC, what is the density and molar mass of the gas? d = 2.21 g/L ; MW = 54.5 g/mol

3. A mixture of helium and neon gases is collected over water at 28oC and 456 mmHg. If the partial pressure of He is 240 mmHg, what is the partial pressure of neon? (vapor pressure of water at 28oC is 28.3 mmHg) PNe = 187.7 mmHg

4. A gas mixture contains three components: 28 g CO, 2.0 g H2 and 8.0 g of O2. If the gases are at STP, what are the partial pressures of each gas? What is the total volume?
PCO = 0.444 atm ; PH2 = 0.444 atm ; PO2 = 0.111 atm ; V = 50.4 L

5. Given the equation:

Zn (s) + 2 HCl (aq) -----> ZnCl2 (aq) + H2(g)

If 520 mL of H2 is collected over water at 28oC and the atmospheric pressure is 1.0 atm, how many g of Zn was used at the start of the reaction? (vapor pressure of water at 28oC is 28.3 mmHg). 1.33 g Zn

6. A sample of 2.0 moles of hydrogen gas is placed in a container with a volume of 10.4 L. What is the pressure of the gas in torr if the gas is at 25oC? P = 3572 torr

7. A 2.4 L sample of gas is placed in a container at 25oC and 2 atm of pressure. If the temperature is raised to 50oC and the volume is changed to 5.6 L, what is the new pressure? P = 0.929 atm

8. A gas is placed in a balloon with a volume of 3.0 L at 35oC and 800 torr. What would be the new volume for the gas if placed under STP? V = 2.8 L

9. How many moles of gas would occupy a volume of 22.4 L at a pressure of 745 torr and a temperature of 26oC? n = 0.894 mol

10. Calculate the volume of 10.8 g of CO2 at STP. V = 5.5 L

11. Calculate the volume of 0.681 g of N2 at STP. V = 0.55 L

12. A gas at 772 mmHg and 35oC occupies a volume of 6.85 L, calculate its volume if the temperature is raised to 50oC at a constant pressure. V = 7.18 L

13. Drano uses a mixture of sodium hydroxide and aluminum powder to generate hydrogen gas and heat when placed in a drain. Calculate the volume of H2 produced at STP if 3.12 g of Al is used. (Mole ratio is 3 H2 to 2 Al). V = 3.88 L

14. A piece of sodium metal undergoes complete reaction with water as follows:

2 Na (s) + 2 H2O (l) -------> 2 NaOH (aq) + H2(g)

The hydrogen gas is collected over water at 25oC. The volume of gas is 246 mL measured at 1 atm. Calculate the number of grams of Na used in the reaction. (vapor pressure of water = 0.0313 atm) 0.448 g Na

This page titled Solutions is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Mark Draganjac via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.