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.