The specific heat of water is 4.2 kJ/kg$\degree$C. The heat needed to warm 8 kg of water from 20$\degree$C to 70$\degree$C is
A) 400 kJ.
B) 420 kJ.
C) 1680 kJ.
D) 2016 kJ.

Question

Quizplus · Accepted Answer

The formula for calculating the heat needed to warm a substance is:
Q = m · c · ∆T
where Q is the heat required (in Joules), m is the mass of the substance (in kilograms), c is the specific heat of the substance (in Joules per kilogram per degree Celsius), and ∆T is the change in temperature (in degrees Celsius).
In this case, we are given:
m = 8 kg
c = 4.2 kJ/kg·°C (note that the specific heat is given in kJ/kg°F, so we need to convert it to kJ/kg·°C by dividing by 1.8)
∆T = (70°C - 20°C) = 50°C
Plugging these values into the formula, we get:
Q = 8 kg · 4.2 kJ/kg·°C · 50°C
Q = 1680 kJ
Therefore, the heat needed to warm 8 kg of water from 20°C to 70°C is 1680 kJ. The closest answer choice is C) 1680 kJ.

The Specific Heat of Water Is 4 °\degree° C the Heat Needed to Warm 8 Kg of Water

The Specific Heat of Water Is 4 $\degree$ C the Heat Needed to Warm 8 Kg of Water