00:01
Hi there.
00:02
In this question, we are given the mass of one of the products and asked to calculate the mass of the reactant.
00:09
So this is going to be a mass -to -mass stochometry problem.
00:12
So for any stochometry problem, we need a balanced equation.
00:16
They gave us the unbalanced equation in the question, but our first step is going to be to balance it.
00:24
So to balance this, right now the oxygens, we have three on the right side and two on the left.
00:30
So we need to get an even number on the right side because there's no way we can have the left side ever give us an odd number of oxygen.
00:39
So by adding a two in front of h2o, there's now four oxygen.
00:44
So if i put a two over here, there's four oxygen and four hydrogen on both sides.
00:49
So the equation is now balanced.
00:52
And we want to produce 24 .32 grams of water.
01:01
And the question is, how many grams of h202 need to decompose to give us that.
01:07
So as i mentioned earlier, this is a mass -to -mass stochometry problem.
01:11
We have the mass of the product.
01:13
So we will need to convert to moles of h -2 -0.
01:19
Then we can use the mole ratio from the balanced equation.
01:22
The mole ratio are the coefficients in the balanced equation.
01:26
So it looks like a 2 -2 ratio.
01:29
And then we can convert to the grams of h -2 -2 that were needed.
01:33
So it looks like three steps to get us from where we're starting to where we're going.
01:38
So let's go ahead and get started...