Question

A sample of glass, which has a specific heat capacity of 0.670·J·g−1°C−1, is put into a calorimeter (see sketch at right) that contains 100.0g of water. The glass sample starts off at 95.7°C and the temperature of the water starts off at 20.0°C. When the temperature of the water stops changing it's 26.5°C. The pressure remains constant at 1atm. Calculate the mass of the glass sample. Be sure your answer is rounded to 2 significant digits.

Answer 1

Answer: The mass of glass sample is 59. g

Explanation:

When glass is dipped in water, the amount of heat released by glass will be equal to the amount of heat absorbed by water.

$Heat_{\text{absorbed}}=Heat_{\text{released}}$

The equation used to calculate heat released or absorbed follows:

$Q=m\times c\times \Delta T=m\times c\times (T_{final}-T_{initial})$

$m_1\times c_1\times (T_{final}-T_1)=-[m_2\times c_2\times (T_{final}-T_2)]$       ......(1)

where,

q = heat absorbed or released

$m_1$ = mass of glass = ? g

$m_2$ = mass of water = 100.0 g

$T_{final}$ = final temperature = 26.5°C

$T_1$ = initial temperature of glass = 95.7°C

$T_2$ = initial temperature of water = 20.0°C

$c_1$ = specific heat of glass = 0.670 J/g°C

$c_2$ = specific heat of water= 4.186 J/g°C

Putting values in equation 1, we get:

$m_1\times 0.670\times (26.5-95.7)=-[100\times 4.186\times (26.5-20.0)]$

$m_1=58.7g\approx 59.g$

Hence, the mass of glass sample is 59. g