Question

In order to complete an experiment you need 0.159 moles of anhydrous CaCl2. The only material in the storage room is CaCl2-2H2O.

Calculate the amount of sample you need for the lab.

Answer 1

To calculate the amount of sample you need for the lab, you need to convert the amount of anhydrous CaCl2 to the amount of CaCl2-2H2O.

The molar mass of CaCl2 is 110.98 g/mol and the molar mass of CaCl2-2H2O is 147.01 g/mol.

The formula weight of CaCl2-2H2O is 147.01 g/mol.

The formula weight of CaCl2 is 110.98 g/mol.

The difference between the two is 36.03 g/mol.

So, you can use the following formula to calculate the amount of sample you need for the lab:

Amount of CaCl2-2H2O = (Amount of anhydrous CaCl2) x (Formula weight of CaCl2-2H2O) / (Formula weight of CaCl2)

Substituting the values given in your question:

Amount of CaCl2-2H2O = (0.159 moles) x (147.01 g/mol) / (110.98 g/mol)

Amount of CaCl2-2H2O = 0.211 moles

Therefore, you need 0.211 moles of CaCl2-2H2O for your experiment.