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1.
(a)
Define absolute zero temperature for an ideal gas
(1mk)
(b)
The diagram in figure 12 below shows an experiment to investigate the
relationship between volume and temperature of a fixed mass of gas at constant pressure
Figure 12
Explain the function of:
(i)
Concentrated sulphuric acid
(ii)
Stirrer
(2mks)
(1mk)
………………………………………………………………………………
(c)
Which measurements are taken in the above experiment
(2mks)
………………………………………………………………………………………………
(d)
How are the measurements used to verify Charles Law
(3mks)
(e)
On the grid shown in figure 13 below sketch a graph of volume (cm3) against
temperature (0C) for the experiment above. Clearly mark with the letter T the absolute
zero temperature.
(2mks)
Figure 13
(f)
What two assumptions are made in the experiment (2mks)
………………………………………………………………………………………………
2.
3.
a)
State the Charles’ law of gases.
b)
The set-up below was used to verify the Charles’ law.
(1mk)
i)
Describe how the apparatus are used to verify the Charles’ law.
(3mks)
ii)
What are the two purposes of the sulphuric acid index?
iii)
Why is the atmospheric pressure not taken into account in this
experiment?
(1mk)
iv)
What physical property of the gas is kept constant in this experiment?
(1mk)
(1mk)
c)
A given mass of hydrogen gas occupies a volume of 1.6m3 at a pressure of
1.5 x 105 Pa and 120C temperature. What volume will it occupy at s.t.p?
(3mks)
a)
Define specific latent heat of vapourization.
b)
What mass of steam initially at 1300C will raise the temperature of 2.0 Kg of
water contained in a 1.0 Kg glass container, from 200C to 500C? (4mks)
Specific heat capacity of steam
Specific heat capacity of water
Specific latent heat steam
Specific heat capacity of glass
=
=
=
=
(2mks)
200J Kg-1 K-1
4200 J Kg-1 K-1
2.26 x 106 J Kg-1
840 J Kg-1 K-1
4. (a) Define the term specific heat of vaporization. (1 mk)
(b) The setup shown below was used to determine the specific latent heat of
vapourisation of water.
Describe how you would use the apparatus to determine the specific latent heat of
vapourisation of water stating any assumption made and the measurements one would
take. (6 mks)
(c) 50g of steam at 100oC was passed into cold water at 20oC. The temperature on the
water rose to 60oC. Determine the mass of cold water used (specific heat capacity of
water = 4200J/KgK and specific latent heat of vapourisation of water = 2.26 x 106 JKg-1)
(4 mks)
5.
(a) Distinguish between heat capacity and specific heat capacity of a substance. (1mk)
………………………………………………………………………………………………
b)
The figure below represent a set up used to determine the specific latent heat
vaporization of water by electrical method.
(i)
State the measurements to be taken in order to achieve the aim of the experiment.
(3mks)
………………………………………………………………………………………………
………………………………………………………………………………………………
(ii)
State the conclusion from the observations made in the figure b(i) above.
(2mks)
………………………………………………………………………………………………
………………………………………………………………………………………………
c)
Why is the latent heat of fussion of water of lower value than latent heat of
vaporization of the same water.
(2mks)
………………………………………………………………………………………………………
6.
a)
Define specific heat capacity
(1mk)
………………………………………………………………………………………………
b)
State two factors that would raise the boiling point of water
(2mks)
………………………………………………………………………………………………
………………………………………………………………………………………………
c)
In a cooling system 100g of steam at 1000C was passed into cold water at 400C.
The temperature rose to 700C (specific heat capacity of water = 4200J kg-1K-1, latent heat of
vaporization of steam = 2.2 x 106Jkg-1)
Calculate
7.
a)
i)
Heat lost by steam
(2mks)
ii)
Heat lost by condensed steam
(3mks)
iii)
The mass of cold water used
(3mks)
Define specific latent heat of vaporization of a substance
(1mk)
………………………………………………………………………………………………
………………………………………………………………………………………………
b)
Explain why food cooks faster in a pressure cooker than in an open sufuria (3mks)
………………………………………………………………………………………………
………………………………………………………………………………………………
c)
32g of dry ice was added to 200g of water at 250C in a beaker of negligible heat
capacity. When all ice had melted, the temperature of water was found to be 100C. (Take specific
heat capacity of water to be 4200JKg-1K-1)
i)
Calculate the heat lost by water
(2mks)
ii)
Write an expression for total heat gained by ice to melt and for
temperature to rise to 100C
(2mks)
………………………………………………………………………………………………
iii)
8.
a)
Calculate the specific latent heat of fusion of ice
(2mks)
State what is meant by absolute zero temperature
(1mk)
………………………………………………………………………………………………
………………………………………………………………………………………………
b)
In an experiment to determine the relationship between volume and temperature,
of a given mass of a gas at constant pressure, the following results were obtained.
Volume (cm3)
31
33
35
38
40
43
Temperature (0C)
0
20
40
60
80
100
i)
Plot an appropriate graph to show the relationship between volume and
temperature.
ii)
(5mks)
Use the graph to calculate the increase in volume of air per unit rise in
temperature
iii)
(3mks)
Give a reason why the volume of a real gas cannot be reduced to zero by cooling
(1mk)
9. a) Ether is put into a beaker which is placed on a thin film of water. A student blows the
ether through a pipe continuously. State and explain the observation made after some time
(2 marks)
………………………………………………………………………………………………………
b) The rate of evaporation can be increased in a number of ways. State two ways in which
this could be achieved
(2 marks)
………………………………………………………………………………………………………
………………………………………………………………………………………………………
c) Differentiate between specific heat capacity and heat capacity
(2 marks)
………………………………………………………………………………………………………
d) An electric kettle rated at 2.5kw contains 1.6kg of water. It is left switched on after
boiling. How much heat energy will be used in turning all the water to steam?
(2 marks)
………………………………………………………………………………………………………
e) Determine how long will it take for the 2.5kw kettle to boil dry
(2 marks)
………………………………………………………………………………………………………
………………………………………………………………………………………………………
10
(a) Define specific hear capacity (1mk)
……………………………………………………………………………………………
(b) 0.2kg of copper at 80oC is put in a well lagged brass calorimeter of mass 0.1kg
containing 0.16kg of sea water at 20oC.
(i) Calculate the final steady temperature of the mixture (specific heat capacity of
copper =400 J kg-1 k-1, brass 380 J kg-1 k-1 , sea water =3900 J kg-1 k-1) (6mks)
………………………………………………………………………………………………
.
(ii) State one assumption made in (i) above (1mk)
………………………………………………………………………………………………
(c) State the factors that affect the boiling point of a liquid (2mk)
………………………………………………………………………………………………
(d) A liquid was cooled and the temperature recorded. The graph of temperature
(y-axis ) against time (x-axis) was plotted. The result is as shown. Describe parts of the
graph A to D (3mks)
Temp
A
B
C
D
Time
AB…………………………………………………………………………………………
BC…………………………………………………………………………………………
CD …………………………………………………………………………………………
11. a)
Define specific latent heat of fusion of a substance
(1mk)
……………………………………………………………………………………………………
A
4 g mass is receiving heat at the rate 100KJ per minutes and its temperature at various
times recorded as follows
Time t (min)
0
1
Temperature
230
250
2
270
6
13
18
23
28
270
270
310
350
390
29
390
390
T (k )
(i)
Plot a graph of temperature against time on the grid provided
(ii)
Use your graph to find
30
(4mks)
a
The specific heat capacity of the substance in its liquid state
( 3mk)
b
Its boiling point
(1mk)
c
Its melting point
(1mk)
d
The specific latent heat of fusion of the substances
(3mks)