Question

UI
A hot solid of certain mass at 100°C is placed in 100 g of water at 20°C. The
final steady temperature recorded is 25°C. Find the mass of the hot solid if the
specific heat capacity of the solid is 0.7 J/gK and that of water is 4.2J/g K.​

Answer 1

Answer:

Given

mass of water = 100g

initial temperature of water = 20°C

specific heat of water = 4.2J/gK

mass of solid = m (let)

initial temperature of solid = 100°C

specific heat of solid = 0.7 J/gK

final temperature = 25°C

According to the law of method of mixtures

Heat lost by hotter body

=

Heat gained by cooler body

mass of solid x specific heat of solid x

change in temperature of solid

=

mass of water x specific heat of water x

change in temperature of water

$m \times 0.7 \times (100 - 25) \\ = \\ 100 \times 4.2 \times (25 - 20) \\ m = \frac{420 \times 5}{0.7 \times 75} \\ m = 40g$