00:01
Here we have a question about the collection of hydrogen gas over water.
00:07
The total pressure of gas over the water is equal to 732 millimeters of mercury.
00:16
This is taking place at a temperature of 30 degrees celsius, and we know that we collect a total volume of gas of 722 milliliters.
00:33
The total pressure is equal to the partial pressure of the hydrogen gas, plus the partial pressure of the water vapor above the liquid water.
00:48
At 30 degrees celsius, the partial pressure of water is equal to 31 .8 millimeters of mercury.
01:01
Thus, the partial pressure of hydrogen is equal to 732 millimeters of mercury minus 31 .8 millimeters of mercury.
01:16
So our partial pressure of hydrogen is 700 .2 millimeters of mercury.
01:25
Now we can use the ideal gas law, pv equals nrt, to calculate the mass of hydrogen gas collected.
01:34
Thus we can solve this for n, the amount of gas in moles, is equal to pv over rt, where r is equal to 0 .0 .0.
01:44
821, liters times atmospheres over moles times kelvin, which are units of the ideal gas constant...