Measurement of specific heat capacity of water by an electrical method

Apparatus

Joulemeter, calorimeter, heating coil, beaker, lagging, thermometer reading to 0.1° C, electronic balance and a low voltage a.c. supply.

Procedure

• Find the mass of the calorimeter $m_{cal}$.

• Find the mass of the calorimeter plus the water $m1$. Hence the mass of the water $m_w$ is $m1 - m_{cal}$.

• Set up the apparatus as shown Record the initial temperature $θ_1$.

• Plug in the joulemeter, switch it on and zero it.

• Switch on the power supply and allow current to flow until a temperature rise of 10° C has been achieved.

• Switch off the power supply, stir the water well and record the highest temperature $θ_2$. Hence the rise in temperature $Δθ$ is $θ_2 - θ_1$.

• Record the final joulemeter reading Q.

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Measurement of specific heat capacity of water by an electrical method

Results

Mass of the calorimeter: $m_{cal}$ =

Mass of the calorimeter plus the water: $m_1$ =

Mass of the water: $m_w$ = $m_1 - m_{cal}$ =

Initial temperature of water: $θ_1$ =

Final temperature: $θ_2$ =

Rise in temperature: $Δθ$ = $θ_2 - θ_1$ =

Final joulemeter reading: $Q$ =

Calculations

Given that the specific heat capacity of the calorimeter ccal is known, the specific heat capacity of water cw can be calculated from the following equation:

Electrical energy supplied = energy gained by water + energy gained by calorimeter

$Q = m_w c_w Δθ + m_{cal} c_{cal} Δθ$