00:01
So in this question, we're given this unbalanced stepwise reaction for the synthesis of sulfur trioxide, which is s solid, so sulfur, and it's solid to say with oxygen gas, forms so2 gas.
00:17
And then we're told that we have two so2 gas reacting with oxygen gas to form two sulfur trioxides.
00:28
Now, in order to balance these, we need to, if we multiply this upper reaction by two, we're going to be able to cancel.
00:40
We'll have two to two, two, and we'll be able to cancel out the sulfur dioxide from each side, and then we add up.
00:48
So we have still two sulfur solid plus two plus one, three oxygen in a gaseous form, and then still two sulfur trioxides.
01:01
And so we're told that we have five grams of sulfur.
01:07
And so the number of moles, that is, that we have to divide by the molecular weight of sulfur, which is 32.
01:12
We're going to get that we have 0 .156, or i'll be more specific, grams per mole.
01:19
Grams cancel out.
01:20
We have 0 .156 moles of sulfur.
01:24
And so now we have to consider how many moles of oxygen are needed to react to that.
01:28
And so if we have for every mole of sulfur, we have two, every two moles of sulfur, we react to with three moles of oxygen.
01:38
So we can say this...