Page 9 - 1202 Question Bank Chemistry Form 4 KSSM

PAPER 3

You have to determine the melting point of a given substance T in a plastic pack.
Using the apparatus supplied, carry out an experiment to determine the melting point of the substance T.

The following are the brief steps of experiment:
1. Heat the substance T until the temperature reaches 70 °C.
2. Start the stopwatch instantly.
3. Record the temperature of substance T at 30-second intervals until the temperature reaches 90 °C.
(a) Record the thermometer readings. [3 marks]
©PAN ASIA PUBLICATIONS
(b) Plot a graph of temperature against time in a graph paper. [5 marks]
(c) Based on the graph plotted, mark and label the melting point substance T. [3 marks]
(d) Explain why the temperature of substance T remains the same for a period of time. [2 marks]
(e) State the physical state(s) of substance T during [3 marks]
(i) 0 s
(ii) 90 s
(iii) 210 s

Note:
If you are not able to carry out the experiment as described above, observe the thermometer readings and record the
temperature in the space provided. Then, answer the question using the data you have recorded.

Time Thermometer reading Temperature (°C) Time Thermometer reading Temperature (°C)
(s) (s)

70 80
0 (i) 120 (v)

60 70

80 80
30 (ii) 150 (vi)
70 70

80 90
60 (iii) 180 (vii)
70 80

80 90
90 (iv) 210 (viii)
70 80

25
Question 3:
(a) When recording the thermometer reading, consider the accuracy of the (c) Make sure you draw the dotted line to indicate how you determine
thermometer by putting the correct decimal place. Do not put unit as the the melting point. SOS TIP
unit is on the heading of the table.
25