If you have 200 grams of #Na_2O#, how many moles of #Na_2O# do you have?

1 Answer
Apr 7, 2016

Answer:

You have #3# and a bit moles of sodium oxide.

Explanation:

#"Moles "= " Mass"/"Molar mass"# #=# #(200*g)/(61.98*g*mol^-1)# #=# #??" moles"#

The signal advantage of doing calculations this way, i.e. including units in the calculation is that it adds an extra level of validation. I wanted an answer in #"moles"#. The calculation as given me an answer in #"moles"#, i.e. #(200*cancelg)/(61.98*cancelg*mol^-1)# #=# #?mol#. Why? Because #1/x^-1# #=# #1/(1/x)# #=# #x#

This is an example of dimensional analysis. You can get very good at it and introduce another level of checking your answser.