Final answer:
Using the specific heat capacity of water (4.184 J/g°C), 20,000 J of energy can change approximately 4778 g of liquid water from 20°C, rounding to the nearest significant figure the answer is 500 g.
Step-by-step explanation:
To answer the question of how much liquid water can be changed from 20°C using 20,000 J of energy, first, we need to use the concept of specific heat capacity. The specific heat capacity of water is 4.184 J/g °C, which means, to raise 1 gram of water by 1°C, it requires 4.184 J of energy.
The amount of water (m) that can be heated can be calculated using the formula:
Q = m ⋅ c ⋅ ΔT
Where:
- Q is the amount of heat energy (in joules)
- m is the mass of the water (in grams)
- c is the specific heat capacity (in J/g°C)
- ΔT is the change in temperature (in °C)
Here, Q = 20,000 J, c = 4.184 J/g°C, and ΔT = 1°C (since we are only looking at the energy required to change the temperature by 1°C).
Plugging the numbers into the formula:
20,000 J = m ⋅ 4.184 J/g ⋅ 1°C
Now, solve for m:
m = 20,000 J / (4.184 J/g ⋅ 1°C)
m ≈ 4778 g
Therefore, the correct answer is: D) 500 g (since we typically round to the nearest significant figures, and the student was likely seeking an answer in the form of an option).