How many joules are needed to warm 25.5 grams of water from 14ºC to 22.5ºC? A. - 8.4x103J B. 9.1 x 102J C. - 9.1x102J D. 8.4x103J

B. 9.1 * 10² J

Explanation:

The formula for the amount of heat (q) absorbed is

q = mCΔT

1. Calculate ΔT

ΔT = 22.5 °C - 14 °C = 8 °C

2. Calculate q

q₂ = mCΔT = 25.5 g * 4.184 J·°C⁻¹g⁻¹ * 8 °C = 9 * 10² J

Note: The answer can have only one significant figure, because you measured the starting temperature of the water only to the nearest degree.