Dissolving 3.21 g of NH4NO3 in 50.0 g of water cools it from 24.9 degrees C to 20.3 degrees C. What is the sign and size of q for the process?

1. The solution mass is the water plus the dissolved solid, 50.0 plus 3.21, which is 53.2 g. 2. The temperature change is 20.3 minus 24.9, which is minus 4.6 degrees Celsius. 3. Heat for the solution is 4.184 times 53.2 times minus 4.6, which is minus 1024 J. 4. The reaction heat is minus that value, so it is plus 1024 J. 5. To two significant figures that is plus 1.0 times ten cubed joules, or plus 1.0 kJ. 6. A positive q means the process absorbed heat, so the dissolution is endothermic. 7. Using only the 50.0 g of water and omitting the dissolved solid gives the 0.96 kJ trap. _Source: OpenStax Chemistry (CC BY 4.0), Ch 5 "Thermochemistry", section 5.2 Calorimetry_