# Question #c8a2e

##### 1 Answer

#### Explanation:

The idea here is that you can use **Dalton's law of partial pressures** to help you find a relationship between the total pressure of gaseous mixture and the partial pressure of

Now, the **mole percent** of a gas that's part of a gaseous mixture is simply the **mole fraction** of that gas multiplied by

#color(blue)("mole%" = chi xx 100)" "# , where

This means that you can use the *mole percent* of gas *mole fraction* of this gas.

#"mole %" = chi x 100 implies chi = "mole %"/100#

Therefore, you have

#chi_"A" = 10/100 = 0.1#

Since the mixture only contains two gases, **must add up** to give

#chi_"A" + chi_"B" = 1#

This means that the mole fraction of

#chi_"B" = 1 - 0.1 = 0.9#

Now, **STP** conditions are *usually* given as a pressure of

**SIDE NOTE** *I say usually because the actual conditions for STP are a pressure of*

*and a temperature of*

*Dalton's law of partial pressures* tells you that the partial pressure of each component of a gaseous mixture is **proportional** to that component's mole fraction.

The total pressure of the mixture can thus be written as

#P_"total" = overbrace(chi_"A" xx P_"total")^(color(red)("partial pressure of A")) + overbrace(chi_"B" xx P_"total")^(color(blue)("partial pressure of B"))#

This means that the partial pressure of

#P_"B" = chi_"B" xx P_"total"#

#P_"B" = 0.9 * "1 atm" = color(green)("0.9 atm")#

You can read more on mole percent and mole fraction here: