00:01
We are given information about a gas sample of o2 that was collected over water, and from this information, we want to determine the number of moles of o2 that was collected in the sample.
00:12
We are told the volume and the temperature of the sample, and we also know the atmospheric pressure and the vapor pressure of water.
00:20
We can use dalton's law in order to find the partial pressure of o2 in the sample, and we need to know this value so that we can use it in the ideal gas equation, to solve for a number of moles of o2 in the sample.
00:35
So for dalton's law, the total pressure, and in this case, that corresponds to the atmospheric pressure, is equal to the sum of all the partial pressures in the gas mixture.
00:47
In this case, that is the partial pressure of oxygen plus the partial pressure of water.
00:55
And in this case, the partial pressure of water and the gas mixture is equal to the vapor pressure, which we are given.
01:02
We also know the atmospheric pressure.
01:05
So we can easily solve for the partial pressure of oxygen to be the atmospheric pressure minus the vapor pressure of water.
01:18
And for now we can leave it in units of tors so that we can do the subtraction and see that p .o2 is equal to 750 tors minus 24 tors, which equals 726 .0 tours of oxygen in the gas sample.
01:46
So now we can use the ideal gas law, bv equals nrt, to solve for n, the number of moles of oxygen, using that partial pressure of o2 that we just solved for in the given volume and temperature in the problem...