Example One:

Q.  A chemistry students needs 4 mol of NaOH for an experiment.  What mass of NaOH should the student get?

Remember: We get the MM form the Periodic table. Don't forget to multiple by the subscripts when necessary.

A. The student should take 160g of NaOH.

Example Two:

Q. In an acid-base titration of hydrochloric acid and limewater Ca(OH) ₂ it was found that 21.0 mL of the acid reacted, until the end point, with 10.0 mL of  limewater (a base).  Find the molarity of the limewater if the acid was 0.20 mol/L.

   
V = 21.0 mL       V = 10.0 mL
M = 0.20 mol/L

2HCl : Ca(OH) ₂
2: 1

The molarity of the limewater is 0.21 mol/L

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