How can I do stoichiometry mole to mole problems?

1 Answer
Oct 27, 2015

Answer:

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.