A sample of Ne gas has a pressure of 694 mmHg with an unknown volume. The gas ha
ID: 518997 • Letter: A
Question
A sample of Ne gas has a pressure of 694 mmHg with an unknown volume. The gas has a pressure of 395 mmHg when the volume is 337 mL , with no change in temperature or amount of gas.
a.) What was the initial volume, in milliliters, of the gas?
When Zn reacts with HCl solution, the products are H2 gas and ZnCl2 . A volume of 437 mL of H2 gas is collected over water at a total pressure of 724 mmHg and 16 degress celsius . The vapor pressure of water at 16 degrees celsius is 14 mmHg .
a.) How many moles of H2 gas were produced in the reaction?
Explanation / Answer
according to gas law, P1V1 = P2V2 (at constant temp)
P1 = 694 mmHg; unknown volume V1 = ?
P2 = 395 mmHg; volume V2 = 337 mL
V1 = P2V2 / P1 = (395* 337) / 694 = 191.8 mL
The volume of the gas at the pressure of 694 mmHg is 191.8 mL or nearly 192 mL
b) Ideal gas law is PV = nRT
P = 724 mmHg = 0.95263 Atmospheres (atm);
V=437 mL = 0.437 L;
R is gas constant =8.2057 *102L atm K1 mol1
temperature = T = 16 degress C = 273 + 16 = 289 K
moles of H2 = n = ?
n = PV /RT = (0.95263*0.437) / (8.2057 *102 * 298)
n = 0.416 / 24.45 = 0.017 mole
No of moles of H2 gas were produced in the reaction is 0.017 mole