Question

1. A 0.0700 kg of brass is heated to 230◦ c and then dropped into a beaker containing 0.900 kg of water. If the final equilibrium temperature of the mixed system is 23.4◦c, find the initial temperature of the water.

Answer 1

Given:

A 0.0700 kg of brass is heated to 230°C and then dropped into a beaker containing 0.900 kg of water. The final equilibrium temperature of the mixed system is 23.4° C.

To find:

Initial temperature of water ?

Calculation:

The heat lost by brass will be equal to heat taken up by water.

Applying PRINCIPLE OF CALORIMETRY:

$\sf \therefore \: H_{brass} = H_{water}$

$\sf \implies \: m_{1} c_{1}\Delta \theta_{1} = m_{2} c_{2}\Delta \theta_{2}$

$\sf \implies \: (0.07)(0.092)(230 - \theta)= (0.9)(1)( \theta - \theta_{i})$

$\sf \implies \: (0.0064)(230 - 23.4)= (0.9)(23.4 - \theta_{i})$

$\sf \implies \: (0.0064)(206.6)= (0.9)(23.4 - \theta_{i})$

$\sf \implies \: 1.32= (0.9)(23.4 - \theta_{i})$

$\sf \implies \: 23.4 - \theta_{i} = 1.46$

$\sf \implies \: \theta_{i} =23.4 - 1.46$

$\sf \implies \: \theta_{i} ={21.94}^{ \circ} C$

So, initial temperature of water is 23.94° C.