Q ≈ -2000 J
Temperature changes can be used to calculate heat transfer. Please note that since the question is based on measured values I rounded for significant figures.
Heat Transfer
In heat transfer, energy can be gained or lost. When energy is gained, temperature increases. However, when energy is lost, temperature decreases. Since the water decreased in temperature, it must have lost energy. This means that Q will be negative. Q represents the transfer of energy, which is measured in joules.
Calculating Energy
To calculate heat transfer we can use the equation q = m·c·ΔT.
For this question, we know that the mass is 75.0g. Specific heat is a constant that every substance has. These values can be found in data tables. For liquid water, c = 4.184. Finally, the change in temperature is -7°C.
In this scenario, 2196.6 joules of energy were lost. Since -7 has one sig fig, this answer can be rounded to 2000 J.
