Question

A 2.15 kg aluminum engine block heats up to 125 C. Engine coolant at 25 C is added to prevent engine block from overheating. If the desired final temp for optimum pref. should be 74 C what is the required mass of coolant in kg that she be added? The specific heat of aluminum and engine coolant are .91 and 2.42 j/gc show all work

Answer 1

Heat absorbed by the engine coolant while it goes from 25 deg celcius to 74 deg celcius can be given as

H_absorbed = mass of coolant added * specific heat capacity * change in temperature = m * 2.42 * 1000 * (74-25) Please note: I have multiplied by 1000 to convert the unit of specific heat capacity from J/gC to J/kgC

Similarly, Heat given by the engine can be written as,

H_given = mass of engine * specific heat capacity * change in temperature = 2.15 * 0.91 * 1000 * (125 - 74) = 99781.5 J

At equillibrium, H_absorbed = H_given

Therefore, m * 2.42 * 1000 * (74-25) = 99781.5 m = 0.841 kg