A 3.0g sample of NaCl is added to a Styrofoam cup of water, and the change in water temperature is 6.5∘C . The heat of solution of NaCl is 3.76 kJ/mol.

Question

What is the mass (in g) of water in the Styrofoam cup?

Answer 1

How much heat, q, is evolved ? That's
q = 3.76 kJ/mol x (3.0g NaCl/58.46 g NaCl) = ?. Then
q = mass H2O x specific heat H2O x delta T.
Substitute and solve for mass H2O