Question

How to calculate the quantity of heat gained or lost in the following change:

3.50 mol of water freezes at 0 degrees C?

Would it be 6.01kJ/ 3.50 mol ?

Answer 1

Not quite.
6.01 kJ/mol x 3.50 mol = ??
Note that your arrangement gives kJ/mol; my arrangement the mol cancel to give kJ as the answer and that is the quantity of heat.

Answer 2

21kj lost

Answer 3

-21.0 KJ (21.0 KJ lost)