Question

What mass of water will undergo a temperature change of 18 °C when it releases 20,000 joules of heat?

A) 500 g
B) 1,000 g
C) 2,000 g
D) 4,000 g

Answer 1

Main Answer:

The mass of water releasing 20,000 J with an 18 °C temperature change is 2,000 g.C) 2,000 g.

Explanation:

When a substance undergoes a temperature change, the heat absorbed or released is given by the equation Q = mcΔT, where Q is the heat energy, m is the mass, c is the specific heat capacity, and ΔT is the temperature change. In this case, the heat released (Q) is 20,000 joules, and the temperature change (ΔT) is 18 °C. To find the mass (m), rearrange the equation: m = Q / (cΔT). Assuming the specific heat capacity of water (c) is approximately 4.18 J/g°C, substitute the values to get the mass.

The answer is found by rearranging the heat transfer equation, Q = mcΔT. By substituting the given values, we have m = 20,000 J / (4.18 J/g°C * 18°C), resulting in approximately 2,000 grams. This calculation implies that 2,000 grams of water will undergo an 18 °C temperature change when releasing 20,000 joules of heat.

The specific heat capacity of water (c) is a crucial factor in this calculation, representing the amount of energy required to raise the temperature of one gram of water by one degree Celsius. The final answer, 2,000 grams, reflects the quantity of water needed to experience the specified temperature change given the provided heat release.

Therefore, the correct answer is C) 2,000 g.

Answer 2

To calculate the mass of water that changes temperature by 18 °C on releasing 20,000 J of heat, use the formula Q = mcΔT with the specific heat of water (4.184 J/g °C). The calculated mass is approximately 265.7 g, so the closest given option is 500 g (Option A).

Step-by-step explanation:

The question asks for the mass of water that will undergo a temperature change of 18 °C when it releases 20,000 joules of heat.

To find the answer, we need to use the formula that relates heat energy change (Q), mass (m), specific heat capacity (c), and change in temperature (ΔT): Q = mcΔT.

Given that the specific heat of water is 4.184 J/g °C and ΔT is 18 °C, we can rearrange the formula to solve for m: m = Q/(cΔT).

Plugging in the values we get: m = 20,000 J / (4.184 J/g °C × 18 °C) = 20,000 J / 75.312 J/g = 265.7 g.

Therefore, the closest option to our calculated value is Option A, 500 g, as the amounts are usually rounded in problems like this.