5
A fixed mass of gas, at a constant temperature of 300 K, exerts a pressure of 100 000 Pa in a
syringe of volume 30cm3 as shown in Fig. 4.1.
syringe
Fig.4.1
(a) (i)
The gas in the syringe is at an absolute temperature of 300 K.
Define the term absolute temperature.
.........
(ai) Convert 300 K to degrees
t11
celsius.
........."c [1]
(iii)
State and explain the effect of increasing the temperature of the gas when the volume
is kept constant.
.....t2)
(b)
The volume of the gas in the syringe is reduced by one quarter, The temperature of the
gas remains constant.
Calculate the new pressure exerted by the gas.
pressure =
6
For
Examiner's
Use
Fig. 4.1 shows an uncatibrated mercury thermometer with two fixed points A and B
marked on it. The fixed points are to be determined using pure water.
mercury thread
Fig. 4.1
(a) What are the temperature values of point A and point B?
Point A =
Point B =
121
(b) Describe an experiment to show that point A has been marked correctly.
€"
q
121
(c)
The distance between points A and B is 25cm.
Determine the temperature reading if the mercury thread stops 15 cm from point A.
€'
E
temperature
reading
................'. t2I
5
For
Examinefs
Fig.4.1 shows apparatus used to investigate the relationship between the temperature and
the p.d. across the hot and cold junctions-of a thermocouple.
,l
fra
c
cold
junction
hot
junction
t
heat
F[g.4.1
(a) Explain why the cold junction
should be kept in melting ice throughout the investigation.
,....,.......,.i..i,r...,...r....,.r..tr.,r
(ir
(iuxt
Use
For
Examinef s
I
t^^
(b) Fig. .zshows a graph of the ternperature against corresponding values of the p'd' as
the oil is heated.
1
200
1
000
800
temp/"C
600
400
200
0
46
t-)r'.::.
l:,
p.d.imV
d1i'; ;,
Fig.4.2
Use the graPh to
(i)
oil and'the P-d. across
Describe the relationship between the temperature of the
the junctions.
(ii)
Find the temperature of the oil when the p.d. is
a value on Kelvin scale.
10
mv. convert this temperature to
temP =
t3l
(c)
Give two
advantages
thermometer.
of a
thermocouple. thermometer
over
a
liquid-in-glass
:
I
For
5
Examiner's
Use
Fig. 3.1 shows a 2000W electric kettle connected to the mains being used to boil some
water. The kettle is placed on an electronic balance and the balance reads 350.0 g.
350.0 s
electronic balance
Fig. 3.1
(a) The specific latent heat of vaporisation of water is 336 J /9.
Explain the meaning of this statement.
t1l
(b) After boiling the water for a while, the balance displays a reading of 330.0 g.
Determine
(i)
the mass of the water vaPorised,
MASS =
t1I
(ii) the amount of heat energy used to vaporise the water,
heat energy =
l2l
(iii) the time taken to vaporise the water.
time =
121
(a) (i)
(ii)
Define absoJute zero.
Siaie the u.aiue of absoluie zeio rn cJagrees Celsius.
_
(b)
,^, -':i
-t
*
,r
"'
' t_., '
Fig" 5- 1 shows a 0-40 kg iron bolt being cooled by immersing it in 8,0 kg of water
at 25 "C.
The specific heat capacity of iron is 450J/(ig;C) and that of water rs 4ZAOJ/(kg"C).
The initialtenrperature of the iron bolt is 900.C.
insuiator
I
I
1'd
waier
Fig. s.1
Find the final temperaiure of the water.
,{
:l
final lemperature =
i3l
For
Examiner's
Use
Fig. 4.1 shows an energy source.
cold wate r
steam out
Earth's surface
-.-l
rl lr
'-,.,1
hot
rock-
Fig.4.1
20'C is pumped down to the hot rock.
The water boils at 100'C and 100 kg of water turns into steam.
1000 kg of cold water at
(a)
State the name of the energy source shown in Fig. 4.1.
I1l
(b)
Calculate
(i)
the energy needed to heat all the water from 20'C to 100
The specific heat capacity of water is 4200J/(kg "C)'
oC,
tzl
energy =
(ii) the energy needed to change 100 kg of water to steam.
The specific latent heat of vaporisation of water is 2.3 x 106J/kg'
energy =
(c)
Suggest one environmental impact of the source of energy in Fig. 4.1
12)
.
t1l
For
3
Exarniner's
Usa
Fig. 2.1 shows a spring balance used to measure the weight of a block of metal.
metalblock
Fig.2.1
fr
(a) (i)
What is the weight of the block?
weight
(ii)
(b)
=
"""""""":"""""""'
=
..............
Calculate the mass of the block. Take g as 10 N/kg.
The volume of the block is 1 10 cm3.
Calculate its density.
density
A gas cylinder contains some gas at a pressure of 6.0
(b)
x
103 Pa
......... t2l
and a temperature of 20 "C.
The cylinder has an internal base area ol 7.1 x 10-2 m2.
Calculate the force exerted by the gas on the base of the cylinder.
For
4
Examinels
Use
of the gas'
(c) The tap of tl-re cylinder is opened to release half the mass
(i)
what change, if any, occurs to the volume
of the gas inside the cylinder?
t1l
(ii)
0
The temperature of the gas in the cylinder drops to "C'
gas?
What effect does this drop have on the prdssure of the
particles'
Explain your answer in terms of the motion of the
[,:
the specific heat capacity of copper'
Fig. 4.1 shows apparatus used to determine
power
(a)
Complete the tabte by narning
Fig' 4'1
the functions of the devices Ml' M2' M' and R'
and givi"ing
5
For
Exaninels
(b)
The copper block has
a
nrass of 1 .4 kg. The block
temperature increases from 25.C to S0 "C.
is heated for 300 s and
its
The specific heat capaeity of copper is 390 J/(kg "C).
(i)
Catculate
1.
the temperature rise of the block,
temperature rise =
2.
the heat energy that causes this temperature rise.
heat energy =
(ii)
The total heat energy supplied by the heater in the 300 s is
1B 000 J.
Calculate
1.
the amount of heat energy lost,
heat lost =
{.,
2.
the rate at which heat energy is lost.
rate of heat loss
(iii)
-
Suggest one way of reducing the heat loss from the block.
17l
Use
4
3
Table 3.1 shows the temperature of a substanc
The substance is a solid at-42'C.
For
e atZminute
Examiner's
intervals, during heating.
t-l.se
Table 3.1
time/minutes
temperaturei "C
(a) Define melting
0
?
4
6
8
10
-42 -39 -39 -39 -30 -15
12
14
16
18
2A
0
16
32
48
63
point.
t1l
(b) What state is the substance at 0'C?
Explain how you obtained your answer.
..'..............'.
....,.........:...
(c)
The substance has a latent heat of fusion of
3
11
..."..
121
300 J /9. lt is heated by a heater nated at
000w.
(i)
Calculate the energy supplied by the heater in 120 seconds.
energy
(ii)
Calculate the mass of the substance that will melt in 120 seconds.
mass
(iii)
........."... t2l
=
l2l
What assumption did you make in answering (c)(ii)?
t1l
Far
7
Exaninels
Use
6
Lemonade is cooled by adding lumps of ice to it. 140g of ice at a ternperature of
0.90k9 oi lemonade fqom 26oC to 12"C.
0"C cools
heat of fusilon of ice is 330000J/kg.
heat capacity af water is 4200J/(kg"C).
specific
The
The latent
(a)
Calculate the amount of energY
(i)
gained bY the ice in melting,
(ii)
gained by the melted ice,
ener$! =
(iii)
lost by the lemonade.
energy =
(b)
........'.....'
'.........-..."'[1]
Find the specific heat capacity of lemonade.
specific heat capacity
(c)
t1l
- ...........
-... ..-.- ..-...'-"t21
The actual amount of heat lost by the lemonade is smaller than that calculated in (aXiii).
Explain why.