When power was turned off to a 30.0 gal.water heater,the temperature of the water dropped from 75.0 °C to 22.5 °C.How much heat was lost to the surroundings? A)-2.49 × 10³ kJ B)-2.49 × 10⁷ kJ C)-2.49 × 10⁴ kJ D)-2.49 × 10¹⁰ kJ E)-2.49 kJ

Question

Quizplus · Accepted Answer

We can use the formula Q = mcΔT to calculate the heat lost, where Q is the heat lost, m is the mass of water, c is the specific heat capacity of water, and ΔT is the change in temperature.

First, we need to convert the volume of water to its mass. The density of water is 1 g/mL, or 1000 kg/m³. Therefore, 30.0 gallons = 113.562 L = 113.562 kg.

Next, we can plug in the values into the formula and solve for Q:

Q = (113.562 kg)(4.184 J/g°C)(75.0°C - 22.5°C) 
Q = 2.49 × 10¹⁴ J = 2.49 × 10⁴ kJ

The answer given in scientific notation is -2.49 × 10¹⁴ J, which means that the answer should be C, since it is the option closest to the calculated answer in kJ.

When Power Was Turned Off to a 30