00:02
Hello, in this question we are given this balanced chemical equation and we want to know what mass, question mark grams, mass is measured in grams, of the chlorine we can prepare if we react 400 milliliters of the hcl gas.
00:24
And we are told that we have excess o2, all of the hcl reacts, and we are at standard temperature and pressure.
00:35
Okay, so let's plan out how we are going to do this.
00:43
We know at stp, one mole of any gas has a molar volume of 22 .4 liters.
00:52
So this would give us a way to get from liters to moles, but right now we are at milliliters.
00:57
So the first thing i want to do is to convert to liters.
01:01
And we can do that because we know there are 1000 milliliters in a liter.
01:05
Then we can convert from liters of hcl to moles of hcl by using our molar volume at stp, 22 .4 liters equals one mole.
01:21
So we will use that for our conversion factor.
01:23
Now we want to convert from moles of hcl to moles of the chlorine.
01:31
And we can do that by using the mole ratio.
01:33
The mole ratio comes to us from the coefficients in the balanced equation.
01:39
Therefore, the mole ratio is going to be, we see a 4 in front of hcl and a 2 in front of cl2.
01:47
So we have that 4 to 2 ratio.
01:49
We use that as a conversion factor.
01:52
And then finally we need to convert from moles to mass of the chlorine.
01:55
So to do that, we will use molar mass.
01:58
Molar mass is the mass in grams of one mole of a substance.
02:02
And we can get that from the periodic table.
02:04
Since this is cl2, we just need to take two times the mass of chlorine from the periodic table...