How To Solve Stoichiometry Problems Step By Step

And you're going to see in chemistry, sometimes people use the word reagents. Aluminum, on the left hand side we only have one aluminum atom. So my question to you is how many grams of aluminum do we need?

For most of our purposes you can use the word reagents and reactants interchangeably. The reagents are sometimes for special types of reactions where you want to throw a reagent in and see if something happens. So remember when we're doing stoichiometry first of all, we want to deal with balanced equations. Well you look at the equation, you immediately see the mole ratio.

Stoichiometric calculations are based on the equalization between the ratio of the amount of substance we're interested in, and the ratio of the corresponding absolute values of the stoichiometric numbers. As before, the path to the solution begins with the first (and hardest) step, which requires of you to not only keep your eyes sharp, but also your mind.

Almost every single stoichiometric task can be solved in five easy steps, and with only a basic knowledge of mathematics. Before you even begin, make sure to carefully read the task itself.

So it's a relationship between the reactants and the products in a balanced chemical equation. Just so we get practice balancing equations, I'm always going to start with unbalanced equations. How many iron atoms do we have on the right hand side? And then we need to have twice as many moles of aluminum. This mass is going to be 2 times 56 plus 3 times 16. But this isn't a math video, so I'll get the calculator out. So in our reaction we said we're starting off with 85 grams of iron oxide. Well 85 grams of iron three oxide is equal to 85 over 160 moles. So we're going to need 1.06 moles of aluminum. So for every mole of this, we need two moles of this.

So if we're given an unbalanced one, we know how to get to the balanced point. Because for every mole of the iron three oxide, we have two moles of aluminum. So that's equal to, 85 divided by 160 equals 0.53125. So everything we've done so far in this green and light blue, we figured out how many moles 85 grams of iron three oxide is. If we have 0.53 moles, you multiply that by 2, and you have 1.06 moles of aluminum.

In a chemical reaction, matter can neither be created nor destroyed according to the law of conservation of mass, so the products that come out of a reaction must equal the reactants that go into a reaction.

This means the same amount of each atom that you put in must come back out.

H2 Ca(Cl O3)2 This shows that for every 2 moles of chloric acid, 1 mol of hydrogen forms.

Thus, 0.207 moles chloric acid leads to 0.207/2 = 0.1036 moles hydrogen.