Heat Energy 2 Flashcards
1
Q
What are the three states of matter?
A
Solid liquid and gas
2
Q
What is the process of a solid changing to a liquid called?
A
Fusion
3
Q
What is the process of a liquid changing to a gas called?
A
Vaporization or evaporation
4
Q
What happens to the temperature of a pure crystalline substance during a change of state?
A
It remains constant
5
Q
Do amorphous substances have definite melting or freezing points?
A
No
6
Q
What is latent heat?
A
The heat supplied or removed which causes a change of state without a change in temperature
7
Q
What is latent heat of fusion?
A
The quantity of heat required to convert a substance from its solid to its liquid state without a change in temperature
8
Q
What is specific latent heat of fusion?
A
The quantity of heat required to convert unit mass of the solid at the melting point to its liquid form without a change of temperature
9
Q
What is the formula for heat involved in a change of state?
A
H = ml
10
Q
What happens when heat is supplied to a solid?
A
It can cause the solid to change to a liquid (fusion)
11
Q
What is the temperature at which a solid melts to its liquid form called?
A
Melting point
12
Q
What is the temperature at which a liquid freezes to its solid state called?
A
Freezing point
13
Q
How do the melting point and freezing point of a pure crystalline substance compare?
A
They are the same
14
Q
What happens to the temperature of a substance while it is undergoing a change of state?
A
It remains constant
15
Q
Do amorphous substances have definite melting or freezing points?
A
No
16
Q
What is thermal capacity?
A
The quantity of heat required to raise the temperature of the entire mass of the body by 1 Kelvin
17
Q
What is another name for thermal capacity?
A
Heat capacity
18
Q
What is the unit of thermal capacity?
A
Joules per Kelvin (J/K)
19
Q
What is the formula for thermal capacity?
A
Cp = mass x specific heat capacity
20
Q
How is heat related to thermal capacity and temperature rise?
A
Heat = Thermal capacity x temperature rise
21
Q
What are the two methods to measure the specific heat capacity of a solid?
A
Electrical method and Method of Mixtures
22
Q
In the electrical method what is used to heat the solid?
A
An electrical heater
23
Q
What is used to reduce heat losses in the electrical method?
A
A lagged jacket
24
Q
What quantities are measured in the electrical method?
A
Current voltage time and temperature rise
25
What formula is used to calculate the specific heat capacity in the electrical method?
c = IVt / (m x θ)
26
What is a calorimeter?
An apparatus used in experiments that involve the exchange of heat between two bodies at different temperatures
27
What materials are calorimeters usually made of and why?
Copper or aluminum because they are good conductors of heat
28
What is the most common method employed in calorimeter experiments?
The method of mixtures
29
What is the principle of the method of mixtures?
Heat lost by hot substance = Heat gained by cold substance
30
What are ways to reduce heat losses in calorimeter experiments?
Lagging the calorimeter providing a lid and polishing the outside of the calorimeter
31
Define temperature.
The degree of hotness or coldness of a body
32
What does temperature determine regarding heat energy?
Which way heat energy will flow
33
How does heat flow between objects of different temperatures?
From higher temperature to lower temperature
34
What form of energy is heat?
Thermal energy
35
What happens to a body's temperature when it absorbs heat?
Its temperature rises
36
What two factors does heat depend on?
Mass and temperature
37
Is heat a measure of total internal energy?
Yes
38
What is temperature related to regarding energy?
Energy of movement
39
What is temperature a measure of regarding molecules?
Average kinetic energy
40
What is the unit of heat?
Joule
41
What are the units of temperature?
Degree Celsius or Kelvin
42
What do thermometers use to measure temperature?
Any physical property that varies with temperature
43
What is a thermometric substance?
A substance whose physical property is used to gauge temperature
44
Name a type of thermometer that uses liquid volume change.
Liquid-in-glass thermometer
45
Name a type of thermometer that uses gas pressure change.
Gas thermometer
46
Name a type of thermometer that uses electrical resistance change.
Resistance thermometer
47
Name a type of thermometer that uses electric potential difference change.
Thermocouple
48
Name a type of thermometer that uses the expansion of metal.
Bimetallic thermometer
49
What are the two reference temperatures of a thermometer called?
Upper fixed point and lower fixed point
50
What is the upper fixed point?
Temperature of steam from pure water boiling at standard atmospheric pressure
51
What is the standard atmospheric pressure in mm of mercury?
760 mm of mercury
52
What is the lower fixed point?
Temperature of pure melting ice at standard atmospheric pressure
53
What is the fundamental interval of a thermometer?
Difference in temperature between the two temperature points
54
Name three types of temperature scales in current use.
Celsius scale Fahrenheit scale Kelvin scale
55
What are the fixed points for the Celsius scale?
0°C and 100°C
56
What are the fixed points for the Fahrenheit scale?
32°F and 212°F
57
Into how many parts is the Celsius fundamental interval divided?
100 equal parts
58
Into how many parts is the Fahrenheit fundamental interval divided?
180 units or degrees
59
What is the SI unit of temperature?
Kelvin (K)
60
What are the fixed points for the Kelvin scale?
273 K and 373 K
61
How many equal parts is the Kelvin fundamental interval divided into?
100 equal parts
62
Is the Kelvin scale measured in degrees?
No in units called Kelvin
63
What is the absolute zero in Celsius?
-273°C
64
What is the formula to convert Celsius to Kelvin?
T = θ + 273
65
What are the two most common liquids used in thermometers?
Mercury and alcohol
66
What does a liquid-in-glass thermometer measure?
Change in volume of a fixed mass of liquid
67
What kind of glass should a liquid-in-glass thermometer have for high sensitivity?
Thin glass bulb
68
What kind of capillary tube should a liquid-in-glass thermometer have for high sensitivity?
Narrow capillary tube with uniform bore
69
What kind of liquid should a liquid-in-glass thermometer have for high sensitivity?
Liquid with high expansivity
70
List three properties a liquid should have to be used as a thermometric liquid.
Expand/contract uniformly with temperature High boiling point and low melting point Be easily seen in glass
71
Does water have the properties to be a good thermometric liquid?
No
72
Why is water not suitable as a thermometric liquid?
Small range of expansion Freezes at 0°C and boils at 100°C Does not expand uniformly Wets glass and is colorless
73
Which is more commonly used in school laboratories and hospitals: mercury-in-glass or alcohol-in-glass?
Mercury-in-glass
74
Is a mercury-in-glass thermometer reliable for accurate work?
No
75
Does mercury or alcohol have a greater conductivity?
Mercury
76
Does mercury or alcohol expand more rapidly?
Mercury
77
Does mercury or alcohol indicate temperature change more quickly?
Mercury
78
Is mercury opaque or transparent?
Opaque
79
Is alcohol opaque or transparent?
Transparent
80
Does mercury or alcohol need to be colored to be seen?
Alcohol
81
Does mercury or alcohol wet glass?
Alcohol
82
Which has a concave meniscus: mercury or alcohol?
Alcohol
83
Does mercury or alcohol lead to inaccurate readings when the thread is falling?
Alcohol
84
Is mercury easily vaporized?
No
85
Is alcohol easily vaporized?
Yes
86
What is the boiling point of mercury?
357°C
87
What is the boiling point of alcohol?
78°C
88
Which can measure higher temperatures: mercury or alcohol?
Mercury
89
What is the freezing point of alcohol?
-115°C
90
What is the freezing point of mercury?
-39°C
91
Which can measure very low temperatures: mercury or alcohol?
Alcohol
92
Which has a greater expansivity for the same temperature rise: alcohol or mercury?
Alcohol
93
What type of thermometer is a clinical thermometer?
Mercury-in-glass thermometer
94
Where is a clinical thermometer used?
Hospitals
95
What does a clinical thermometer measure?
Human body temperature
96
What is the approximate normal temperature of a healthy person?
37°C
97
What is the temperature range of a clinical thermometer?
35°C to 43°C
98
What kind of bulb does a clinical thermometer have?
Small bulb made of thin glass
99
What kind of bore does a clinical thermometer have?
Narrow bore
100
What does the narrow bore of a clinical thermometer allow?
Small temperature changes to cause large changes in mercury column length
101
What is the prominent feature of a clinical thermometer?
Kink or constriction of bore near the bulb
102
What does the kink in a clinical thermometer do?
Allows expanding mercury to flow past it but prevents it from returning quickly
103
How can mercury be returned to the bulb in a clinical thermometer?
By vigorously shaking the thermometer
104
Why do some clinical thermometers have a thick stem?
For easy viewing of the mercury thread
105
Is it advisable to sterilize a clinical thermometer in boiling water?
No
106
Why is it not advisable to sterilize a clinical thermometer in boiling water?
Small temperature range/glass will break due to excessive expansion
107
What type of thermometer is used by weather-men in meteorological stations?
Combined maximum and minimum thermometer
108
What does a combined maximum and minimum thermometer record?
Maximum and minimum temperatures for the day
109
What is the name of a commonly used combined maximum and minimum thermometer?
Six's Combined Maximum and Minimum Thermometer
110
What is the shape of the stem of a Six's thermometer?
U-shaped
111
How many bulbs does a Six's thermometer have?
Two
112
What liquid is contained in the bulbs of a Six's thermometer?
Alcohol
113
What separates the alcohol in a Six's thermometer?
Column of mercury
114
Are both bulbs in a Six's thermometer completely filled with alcohol?
No
115
What do the steel indexes in a Six's thermometer float in?
Alcohol
116
What does the lower end of the first steel index indicate?
Maximum temperature
117
What causes the first steel index to move?
Expansion of alcohol pushing the mercury
118
What does the second steel index indicate?
Minimum temperature
119
What causes the second steel index to move?
Contraction of alcohol causing mercury to move
120
How do the steel indexes remain in their positions?
Tiny springs
121
How are the indices reset?
Using a magnet
122
Are mercury-in-glass thermometers suitable for extremely accurate temperature measurements?
No
123
Why are mercury-in-glass thermometers not suitable for extremely accurate measurements?
Glass also expands with temperature/thermometers have a relatively small range
124
What is the principle of the gas thermometer based on?
Pressure of a gas increases linearly with increase in temperature at constant volume
125
What does a constant volume gas thermometer consist of?
Large bulb with gas/narrow glass tube/mercury manometer
126
What happens to the gas when the bulb is heated?
Gas expands and pushes mercury
127
Is the expansion of glass significant compared to the gas expansion?
No
128
How is the gas kept at constant volume?
By moving the manometer
129
How is the pressure of the gas read?
From the manometer
130
How is gas pressure calculated when the mercury level in A is above that in B?
Atmospheric pressure (H) plus difference (h) in levels (H + h)
131
How is gas pressure calculated when the mercury level in A is below that in B?
H - h
132
How is the thermometer calibrated?
Measuring gas pressure in melting ice and steam
133
What kind of graph is plotted?
Straight line graph of pressure versus temperature
134
What temperature does the graph cut the temperature axis at?
-273°C
135
What is this temperature known as?
Absolute zero temperature
136
What is the pressure of the gas at absolute zero temperature?
Zero
137
What is the kinetic energy of gas molecules at absolute zero temperature?
Zero
138
List three advantages of a gas thermometer.
Very sensitive/accurate/consistent/wide range
139
List two disadvantages of a gas thermometer.
Large and cumbersome/requires knowledge of gas pressure at fixed points
140
What are thermoelectric thermometers used for?
Measuring very high temperatures
141
What is the principle of thermoelectric thermometers?
Thermocouple
142
What happens when two different metals are joined and one end is heated?
An electric current flows
143
What is the junction that is heated called?
Hot junction
144
What is the other junction called?
Cold junction
145
What is the thermoelectric effect?
Generation of electric current when two different metals are joined and one end is heated
146
What is a thermocouple?
The setup of two different metals joined at ends
147
What measures the size of the current in a thermocouple?
Sensitive galvanometer
148
What is the current dependent on?
Difference between temperatures of hot and cold junctions
149
What is the galvanometer usually calibrated to read?
Temperature of the hot junction directly
150
What is a thermoelectric thermometer?
Instrument using the thermoelectric effect to measure temperature
151
Where are thermoelectric thermometers used?
Industry
152
List three advantages of thermoelectric thermometers.
Very sensitive/can measure rapidly changing temperatures/can measure high temperatures/small in size
153
What fact does this thermometer use?
Electrical resistance of a metallic conductor changes proportionally with temperature
154
What happens to resistance as temperature increases?
Resistance increases
155
What does a resistance thermometer consist of?
Long thin platinum wire wound round a spool
156
What is the spool made of?
Mica or silica
157
What is the wire connected to?
Resistance measuring device
158
Name a resistance measuring device.
Wheatstone bridge
159
If a platinum wire has resistance R0 at 0°C and R100 at 100°C
what is the formula for temperature t?
160
Are resistance thermometers useful for measuring very low or very high temperatures?
Yes
161
What are the three states of matter?
Solid liquid and gas
162
What is the process of a solid changing to a liquid called?
Fusion
163
What is the process of a liquid changing to a gas called?
Vaporization or evaporation
164
What happens to the temperature of a pure crystalline substance during a change of state?
It remains constant
165
Do amorphous substances have definite melting or freezing points?
No
166
What is latent heat?
The heat supplied or removed which causes a change of state without a change in temperature
167
What is latent heat of fusion?
The quantity of heat required to convert a substance from its solid to its liquid state without a change in temperature
168
What is specific latent heat of fusion?
The quantity of heat required to convert unit mass of the solid at the melting point to its liquid form without a change of temperature
169
What is the formula for heat involved in a change of state?
H = ml
170
According to the kinetic theory of matter what are all matter composed of?
Tiny particles called molecules
171
What are molecules always doing?
In motion with varying velocities
172
What happens to the velocity and kinetic energy of molecules when a substance is heated?
They increase
173
What is temperature proportional to regarding molecules?
Average kinetic energy
174
If the same quantity of heat is given to two bodies of different masses which body becomes hotter?
The body with smaller mass
175
Why does the body with smaller mass become hotter?
It contains fewer molecules to share the heat
176
What is the average kinetic energy of molecules at absolute zero temperature?
Zero
177
What is the temperature at absolute zero?
-273°C
178
What is the pressure of a gas at absolute zero temperature?
Zero
179
What is temperature?
Degree of hotness or coldness of a body
180
What does temperature determine?
Direction of heat flow
181
What form of energy is heat?
Thermal energy
182
What are examples of physical properties used by thermometers?
Volume of liquid Gas pressure Electric potential difference Electrical resistance
183
What type of thermometer uses the variation of volume of liquid with temperature?
Liquid-in-glass thermometer
184
What type of thermometer uses the variation of gas pressure?
Gas thermometer
185
What type of thermometer uses the variation of electric potential difference?
Thermoelectric thermometer
186
What type of thermometer uses the variation of electrical resistance?
Resistance thermometer
187
What kind of thermometer is a clinical thermometer?
Mercury-in-glass thermometer
188
What is the temperature range of a clinical thermometer?
35°C - 43°C
189
What feature does a clinical thermometer have?
Constriction or kink near the bulb
190
What is the relationship between Kelvin and Celsius scales?
T(K) = 273 + θ°C
191
What is the change of 1°C equal to?
Change of 1 K
192
