Page 42 - PRE-U STPM CHEMISTRY TERM 1

Chemistry Term 1 STPM

At high enough pressure, carbon dioxide undergoes 2
condensation causing a very large decrease in the volume
1
(or a large increase in ). After that, pressure has little Pressure/atm
V
effect on the volume because liquid carbon dioxide is Solid Liquid
difficult to compress. Gas
Quick Check 4.2
3
1 3.15 dm 3 329 °C Temperature
2 323 °C 4 18.93 dm 3
Quick Check 4.3 3 (a)
1 (a) 8.75 dm (b) 50.0 dm 3 Pressure/atm
3
2 (a) 227 (b) 1481.8 dm 3
3 C H 4 C H
3 6 3 8
Quick Check 4.4
3
1 5.00  10 m 2 27.3
–3
3 0.0173 m –3 4 31.08 dm 3 Temperature
Quick Check 4.5 (b) Melting of iron is accompanied by a decrease in
1 (a) 9.01 kPa (b) 5.01 kPa volume. As a result, the melting point decreases with
increasing pressure.
2 8.61
4 (a) & (b)
3 (a)
Gas CO N 2 SO 2
Pressure/atm Critical point
Pressure/kPa 120 72 48
(b) (i) P (CO) = 120 kPa 1 X
P (N ) = 72 kPa Liquid
2
(ii) Total pressure = 192 kPa Solid
Gas
4 (a) 498.6 kPa
(b) 2493 kPa
(c) 997.2 kPa Temperature/°C
M.p. B.p 132
The water vapour pressure is negligible.
(c) Yes. The critical temperature is higher than room
Quick Check 4.6 temperature.
23
–1
1 6.0 10 mol (d) On the graph
2 8 atoms (e) (i) Nothing happens
3 MS (ii) Solid → Liquid → Gas
(f) Density of solid is higher than the liquid
Quick Check 4.7
5 CO , NH , C H OH, H O
1 (a) Conversion of a substance from solid to gas/vapour 2 3 2 5 2
without passing through the liquid phase Quick Check 4.9
(b) Reducing pressure to below 0.006 atm 1 77.44 g
2 (a) Vapour 2 0.838
(b) A Condensation 3 2.95 kPa 3x
Temperature Freezing 4 (a) 2 (c) 7.5x
x
2
(b) 2x
(d)
2
Quick Check 4.10
1 100.17 °C
B
Time 2 –0.084 °C
(c) Increasing the pressure. Vapour → Liquid 3 CaCl
2
Quick Check 4.8 4 (a) Ethanoic acid undergoes association in benzene.
2CH COOH → (CH COOH)
1 The molecules are more closely packed in solid CO 3 3 2
2 (b) Aluminium chloride undergoes association.
compared to liquid CO .
2 2AlCl → Al Cl
3 2 6
365

12 Answers.indd 365 3/26/18 4:06 PM