Physics 5054 · O Level · Melting, boiling and evaporation

Melting, boiling and evaporation — practice question

A student performs an experiment to determine a value for the specific latent heat of fusion of ice. He has to find the mass of ice melted by the heater in time $t$. He uses the apparatus shown in Fig. 2.1.
(a)[1]

State what the student must do before the heater is switched on.

(b(i))[1]

Suggest why the student waits a further minute after switching off the heater before taking a reading from the balance.

(b(ii))[2]

State the current $I$ and voltage $V$ readings when the heater is switched on.

(b(iii))[1]

Using the equation $E = I \times V \times t$ calculate the energy $E$ supplied by the heater when $t = 5.0\,\text{minutes}$.

(b(iv))[2]

The mass $m$ of ice melted in $5.0\,\text{minutes}$ is $36.2\,\text{g}$. The specific latent heat of fusion $L$ of ice is given by $L = \frac{E}{m}$. Calculate a value for $L$ and give a unit for your answer.

(c)[2]

The teacher tells the student that his value is different from the accepted value. Apart from your answer in (a), suggest two improvements to the experiment.

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: Weigh the empty beaker or zero the balance

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