**Problem : **
What is the density of carbon dioxide at 298 K and 1.0 atm?

d = = |

**Problem : **
10 L of an unknown gas has a mass of 10.8 grams at a temperature of 310 K and
1.2 atm. What is the molar mass of the gas?

μ = |

If we use

**Problem : **
A syringe of 0.010 mol O_{2} and a syringe of 0.060 mol H_{2} are forcibly
injected into an evacuated glass jar of volume 1.0 L and temperature 273 K.
What is the total pressure, and what are the partial pressures, of O_{2} and
H_{2}?

There are 0.010 + 0.060 = 0.070 mol of gas in the jar. Since we know volume
and temperature, we can rearrange *PV* = *nRT* to find the total pressure. Using
the value *R* = 0.0821 , we find that
*P*_{tot} = 1.6 atm.

To solve for the partial pressures of each gas, we use Charles' law. The
mole fraction of O_{2} is 0.010/0.070 = 0.14, so the partial pressure of
O_{2} is 14% of the total pressure, or 0.23 atm. Likewise, the mole fraction of
H_{2} is 0.060/0.070 = 0.86, so the partial pressure of H_{2} is 1.4
atm.

Alternatively, you could have found the partial pressures directly and summed them to find the total pressure. Try both ways to see which works best for you.

**Problem : **

P_{a2} | = | ||

= | |||

= | |||

= | 1.0×10^{5} Pa |

= 1/2 for both gases. A similar calculation for gas B gives

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