Question

How can I do stoichiometry mole to mole problems?

Answer 1

By learning how to balance chemical equations.

Explanation:

Let's take a look at the simplest example:

`2H_2` + `O_2` = `2H_2O` (balanced equation)

Given the equation above, how many moles of `O_2` will react with sufficient number of moles of `H_2` do you need to produce 10 moles of `H_2O`?

From the balanced equation, already know that for every 1 mole of `O_2`, it produces 2 moles of `H_2O`, or simply put:

1 mole `O_2` = 2 moles `H_2O`

Therefore, in order to get the number of moles for `O_2`,

`10` `cancel "mol"` `H_2O` x `(1 "mol" O_2)/(2 cancel ("mol") H_2O)` = `5` `"mol"` `O_2`

If 5 moles of `O_2` are needed to produce 10 moles of `H_2O`, how many moles of `H_2` do you need to react?

Again, from the balance equation, you will see that every 1 mole of `O_2` needed 2 moles of `H_2` to produce 2 moles of `H_2O`, or simply put,

1 mole `O_2` = 2 moles `H_2`

Thus,

`5` `cancel "mol"` `O_2` x `(2 "mol" H_2)/(1 cancel ("mol") O_2)` = `10` `"mol"` `H_2`

See? Everything starts by properly balancing the equation first because that is where you can get your "conversion factors" in order to solve the mole-to-mole problems.