A reaction lowers the temp of 50.0g of water by 2.00C.What is the enthalpy change for the reaction?

Question

The specific heat of water is 4.18 J K-1 g-1.

Answer 1

Quantity of energy lost by the water:

Q = (m)(deltaT)(c)
= (50.0g)(2.00 C)(4.18 JK-1g-1)
= 418 J

Since the water got colder, the reaction was endothermic, and the enthalpy change for the reaction is +418 J.