Jawaban:

e. 72,5 °C

Penjelasan:

To find the final temperature of the mixture of lead and water, you can use the specific heat equation presented as follows:

Q = mcΔT

Where:

Q = heat transferred (cal)

m = mass of substance (g)

c = specific heat of substance (cal/g • °C)

ΔT = change in temperature (°C)

It is known that the mass of lead is 300 g with a temperature of 100 °C, and the mass of water is 100 g with a temperature of 70 °C. The specific heat of lead is 0.030 cal/g • °C.

Then, you can calculate the change in temperature of the mixture of lead and water using the equation above, as seen in the steps below:

Calculate the heat required for lead to decrease its temperature to the temperature of water.

Q = mcΔT

= (300 g)(0.030 cal/g • °C)(100 °C - 70 °C)

= 2700 cal

Calculate the heat required for water to increase its temperature to the final temperature.

Q = mcΔT

= (100 g)(1 cal/g • °C)(T - 70 °C)

= 100T - 7000

Determine the final temperature of the mixture by equating the heat gained by water to the heat lost by lead.

2700 cal = 100T - 7000

7000 cal = 100T

T = 70 °C

Therefore, the final temperature of the mixture is 70 °C, which corresponds to the answer choice (e) 72.5 ºC.