Question

If a reaction is performed in 155 g of water with a heat capacity of 4.184 J/g °C and

the initial temperature of a reaction is 19.2°C, what is the final temperature (in units
of °C) if the chemical reaction releases 1420 J of heat?

Answer choices:
21.4
29.2
27.4
34.5

Answer 1

For this exercise, the formula for calculating heat is needed

`Q = m × c_(s) × ∆T`

In this case, we need to fInd the difference in temperature of the water, so

`∆T = (Q)/(m × c_(s)) = (1420 J)/(155 g × 4,184 J/g °C) = 2,2 °C`

Since water accepts heat from the reaction, its temperature increases therefore the final temperature is

`T_(f) = T_(0) + ∆T = 19,2 °C + 2,2 °C = 21,4 °C`