00:02
Hello, in this question we are given this balanced equation and we are told that we're trying to burn or combust 8 .0 grams of the methane.
00:12
The methane is ch4 and we want to know how many moles of oxygen are going to be required to do that.
00:20
Okay, so this is a stoichiometry problem.
00:24
We are starting with information about one substance in the equation and we're trying to determine information about another substance in the equation.
00:32
Well, to convert from one substance to another, we use the mole ratio and the mole ratio comes from the coefficients in the balanced equation.
00:41
Since there's nothing written in front of ch4, it's understood to be a 1.
00:45
That means that for every 1 mole of ch4, we need 2 moles of the oxygen because oxygen's coefficient is a 2.
00:54
Alright, so in order to use this mole ratio to get us 2 moles of the oxygen, we need to first convert from grams of methane to moles of methane.
01:14
And to convert from grams to moles, we use molar mass.
01:18
Molar mass is the mass of 1 mole of a substance in grams.
01:22
So if we have 1 mole of methane, ch4, we will use the molar masses on the periodic table, add together the mass of 1 carbon and 4 hydrogen, and we get a molar mass of 16 .05 grams in every mole.
01:45
Okay, so we can use that equality to convert to moles and then use the mole ratio to convert to moles of oxygen...