4.1 Heat: Thermal Equilibrium
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Sek Men Sains Muzaffar Syah
4.1 Getting Idea of heat transfer The boy takes his hand away from the kettle because the boy feels the heat of the kettle. Heat is transferred from the kettle to the boy’s hand. The ice melt when it is in the boy’s hand. The boy’s hand is cooled. Heat is transferred from the boy’s hand to the ice. Heat is transferred from hot object to cold object.
Comparison between Temperature and Heat Characteristic Definition
Temperature Temperature is the degree of ____________ of an object.
Heat Heat is the amount of _________ that can be transferred from _________ object to a __________ object.
Unit SI Measurement instrument Base / derived quantity? Scalar / vector quantity
Joulemeter or calorimeter
When an object is heated, it will ____________ heat energy and the temperature will _________ When an object is cooled, it will ___________ heat energy and the temperature will _________. (Hands-on Activity 4.1 on page 72 of the practical book)
Thermal Equilibrium Block A is hot and block B is at room temperature. What will happen if the two blocks are in direct physical contact?
Heat energy is transferred at a __________ rate from the hot objects A to the cold object B. Heat is transferred at a __________ rate from the cold object B to the hot object A.
1
Sek Men Sains Muzaffar Syah
What happens to the temperature of the blocks? Why? The hot object A _________ heat while the cold object B ________ heat. The temperature of block A __________, the temperature of block B ____________ Heat transferred to B ___________ the kinetic energy of its molecules The net result is the transfer of heat energy from the _______ object to the _________ object. What happens to rate of heat transfer after sometimes? After sometimes, heat is transferred at the same rate between the two blocks. The net rate of heat transferred between the two object becomes _______ The temperature of block A _________ to the temperature of block B. The molecules of both objects have the same __________ energy. The two objects are said to be in __________ ____________.
Explain Thermal Equilibrium
Thermal Equilibrium can be summarized as follows: 1. There is no net flow of heat between two objects. 2. Two objects in thermal equilibrium have the same temperature.
Example of thermal equilibrium A wet towel is placed on the forehead of a person who has high fever. Initially the temperature of the cloth is lower than the body temperature of the person. Heat energy is transferred from the forehead to the towel until thermal equilibrium is reached. The towel is rinsed in tap water and the procedure is repeated. In this way heat energy is removed from the person. Cooling drinks A hot drink can be cooled by adding a few ice cubes to the drink. Heat from the hot drink is transferred to the colder ice until thermal equilibrium between the ice and water is reached. The final temperature of the drink equal the final temperature of ices.
Explain how a liquid-in-glass thermometer works. A doctor uses a thermometer to measure a patient’s body temperature. There is a difference in temperature before and after the measurement. Why? The thermometer is placed in the patient’s ________ There is a ______ flow from the patient to the thermometer. This will happens until ___________ ____________ is achieved. The patient’s body temperature and the thermometer temperature are ____________. Temperature is measured using a liquid-in-glass thermometer. The bulbs contains a fixed mass of liquid such as ___________. The volume of the liquid increases when it absorbs heat. The liquid ___________ and rises in the capillary tube. Therefore the length of the liquid column in the capillary tube indicates the magnitude of the temperature.
2
Sek Men Sains Muzaffar Syah
How a thermometer is calibrated? A scale and unit of temperature are obtained by choosing two temperatures or fixed points.
Fixed point Lower point, ice point
Definition
Value (C)
Upper point, Steam point The range between the fixed points is divided into 100 equal divisions and each division equal 1 C. The thermometer is calibrated and ready for use
Example 1:
Calculate the value of temperature, T.
Give three characteristics of mercury that makes it suitable as a liquid in liquid-in-glass thermometer. ____________________________________________________________ ____________________________________________________________ ____________________________________________________________
3
Sek Men Sains Muzaffar Syah
TUTORIAL 4.1
5.
The diagram shows a metal sphere P at o 80 C is immersed in a cooler liquid Q.
1. Which of the following is true? A. The unit of heat is o C B. Heat is a form of energy C. Heat flows from a cold substance to a hot substance. 2. A boy puts some ice cubes in his orange juice. There is energy transferred between the ice cube and the juice. Which of the following properties determines the direction of such exchange? A. Density B. Temperature C. State of matter D. Specific Heat Capacity
Thermal equilibrium is reached when A. temperature of P = temperature of Q B. mass of Q displaced = mass of P C. volume of Q = volume of P D. specific heat capacity of P = specific heat capacity of Q 6.
3. The diagram shows two bodies P and Q which are in thermal equilibrium.
A. B. C. D.
4.
Which of the following statements is not true? The net rate of heat flow is zero The heat flow in both directions is the same. The final temperature of both bodies is the same. The final physical characteristics of both bodies are the same.
An earth-monitoring satellite falls into the earth’s atmosphere at a high velocity and reaches at the sea surface with a high temperature. After a while the temperature of the satellite is same as the temperature of the sea water. This is caused by A. The heat released by the satellite B. The heat absorbed by the sea water C. The satellite is cooled by the sea water D. The satellite and the sea water are in thermal equilibrium
The diagram shows two copper blocks, L and M, touching each other. The initial o temperatures of L and M are 50 C and o 30 C respectively.
Which statement is correct when L and M are at thermal equilibrium? A. Temperature of L is higher than M B. The quantity of heat in L is the same as in M C. Rate of change in temperature of L is bigger than that of M D. Net rate of heat flow between L and M is zero 7.
The diagram shows object A and object B are of temperatures T1 and T2. The heat flows from A to B until the thermal equilibrium is reached at a temperature T.
Which relationship between T1 , T2 and T is true? A T1 > T2 > T B T2 > T1 > T C T1 > T > T2 D T2 > T > T1
4
Sek Men Sains Muzaffar Syah
8.
What is the concept used in the measurement of human body temperature using a thermometer? (2007) Principle of conservation of temperature A. Specific heat capacity B. Specific latent heat C. Thermal equilibrium D. Thermal convection
9. Which of the following points are used in the calibration of a thermometer? A. Melting point of ice and freezing point of ice. B. Melting point of ice and boiling point of water. C. Boiling point of water and condensation point of water. D. Melting point of ice and condensation point of water. 10. The lengths of the mercury column in a thermometer at the ice point and the steam point are 5 cm and 25 cm respectively. When the thermometer is placed in a liquid , the length of the mercury column is 12 cm. What is the temperature of the liquid? o o A 30 C B 35 C o o C 55 C D 70 C o E 85 C 11. Which liquid A , B, C or D , can be used to make a liquid –in-glass thermometer to o o measure temperatures from -50 C to 50 C? Freezing Boiling o o point / C point / C A -115 78 B -39 357 C 0 100 D 17 118
Which statement is correct about the temperature of the final mixture? (2008) A. It is lower than the temperature of the cold syrup. B. It is lower than the temperature of the hot water C. It is higher than the temperature of the hot water D. It is the same as the temperature of the cold syrup A. B. C. D.
14. The figure shows a mercury thermometer.
(a) Name component P: _______________________ Q: _______________________ (b) (i) State the physical change in the mercury when the temperature increases. __________________________ (ii) Why is mercury used in the thermometer? __________________________ (b)
12. Diagram 12.1 shows hot water being poured into cold syrup. Diagram 12.2 shows the final mixture.
sticks to the glass has a lower boiling point expands and contracts uniformly is transparent and therefore it is easier to read.
The length of the mercury column in the thermometer is 2.6 cm at 0°C and 22.6 cm at 100 °C? (i) What is the difference in the lengths of the mercury columns at 0 °C and at 100 °C? ________________________ (ii) When the thermometer is placed in hot oil, the length of the mercury column is 16.9 cm. Calculate the temperature of the hot oil.
5
Sek Men Sains Muzaffar Syah
SPM 2003 Section C 15. You are representing the country in carrying out a research project on the weather at the North Pole. The surrounding temperature is between o o 40 C to - 8 C. One item of the equipment to be taken for your research is a thermometer. (a) State the principle used in a liquid – glass thermometer. (b) State how a liquid-glass thermometer can be used to measure the body temperature of a sick person. Explain heat transfer that takes place at each stage of measurement.
Additional information: o Freezing point of mercury = -39 C Boliling o point of mercury = 360 C o Freezing point of alcohol = - 112 C Boiling o point of alcohol = 78 C
Based on the table above; (i)
(ii)
(b)
Thermometer
(c) The table shows the characteristics of six types of thermometers P,Q,R,S,T and U. Liquid Glass Diameter Glassused walled of bore bulb capillary stem tube and crosssection P mercury thin big thick and curved
Q
mercury
thick
small
thin and plane
R
mercury
thin
small
thin and curved
S
alcohol
thick
big
thick and plane
T
alcohol
thin
small
thick and curved
U
alcohol
thick
small
thin and plane
Explain the suitable characteristics of the thermometer so that can be used to measure temperatures at the North Pole. Decide which thermometer is most suitable to be taken for your research and give reasons. A thermometer which is not calibrated has a mercury column of length 8.0 cm o when the temperature is 0 C and 20.0 o cm when the temperature is 100 C. The mercury column is 5.0 cm when put in liquid X. (i)
Determine the temperature of liquid X in Kelvin.
(ii) State a thermometric property used when making of a thermometer.
6
4.1 Getting Idea of heat transfer The boy takes his hand away from the kettle because the boy feels the heat of the kettle. Heat is transferred from the kettle to the boy’s hand. The ice melt when it is in the boy’s hand. The boy’s hand is cooled. Heat is transferred from the boy’s hand to the ice. Heat is transferred from hot object to cold object.
Comparison between Temperature and Heat Characteristic Definition
Temperature Temperature is the degree of ____________ of an object.
Heat Heat is the amount of _________ that can be transferred from _________ object to a __________ object.
Unit SI Measurement instrument Base / derived quantity? Scalar / vector quantity
Joulemeter or calorimeter
When an object is heated, it will ____________ heat energy and the temperature will _________ When an object is cooled, it will ___________ heat energy and the temperature will _________. (Hands-on Activity 4.1 on page 72 of the practical book)
Thermal Equilibrium Block A is hot and block B is at room temperature. What will happen if the two blocks are in direct physical contact?
Heat energy is transferred at a __________ rate from the hot objects A to the cold object B. Heat is transferred at a __________ rate from the cold object B to the hot object A.
1
Sek Men Sains Muzaffar Syah
What happens to the temperature of the blocks? Why? The hot object A _________ heat while the cold object B ________ heat. The temperature of block A __________, the temperature of block B ____________ Heat transferred to B ___________ the kinetic energy of its molecules The net result is the transfer of heat energy from the _______ object to the _________ object. What happens to rate of heat transfer after sometimes? After sometimes, heat is transferred at the same rate between the two blocks. The net rate of heat transferred between the two object becomes _______ The temperature of block A _________ to the temperature of block B. The molecules of both objects have the same __________ energy. The two objects are said to be in __________ ____________.
Explain Thermal Equilibrium
Thermal Equilibrium can be summarized as follows: 1. There is no net flow of heat between two objects. 2. Two objects in thermal equilibrium have the same temperature.
Example of thermal equilibrium A wet towel is placed on the forehead of a person who has high fever. Initially the temperature of the cloth is lower than the body temperature of the person. Heat energy is transferred from the forehead to the towel until thermal equilibrium is reached. The towel is rinsed in tap water and the procedure is repeated. In this way heat energy is removed from the person. Cooling drinks A hot drink can be cooled by adding a few ice cubes to the drink. Heat from the hot drink is transferred to the colder ice until thermal equilibrium between the ice and water is reached. The final temperature of the drink equal the final temperature of ices.
Explain how a liquid-in-glass thermometer works. A doctor uses a thermometer to measure a patient’s body temperature. There is a difference in temperature before and after the measurement. Why? The thermometer is placed in the patient’s ________ There is a ______ flow from the patient to the thermometer. This will happens until ___________ ____________ is achieved. The patient’s body temperature and the thermometer temperature are ____________. Temperature is measured using a liquid-in-glass thermometer. The bulbs contains a fixed mass of liquid such as ___________. The volume of the liquid increases when it absorbs heat. The liquid ___________ and rises in the capillary tube. Therefore the length of the liquid column in the capillary tube indicates the magnitude of the temperature.
2
Sek Men Sains Muzaffar Syah
How a thermometer is calibrated? A scale and unit of temperature are obtained by choosing two temperatures or fixed points.
Fixed point Lower point, ice point
Definition
Value (C)
Upper point, Steam point The range between the fixed points is divided into 100 equal divisions and each division equal 1 C. The thermometer is calibrated and ready for use
Example 1:
Calculate the value of temperature, T.
Give three characteristics of mercury that makes it suitable as a liquid in liquid-in-glass thermometer. ____________________________________________________________ ____________________________________________________________ ____________________________________________________________
3
Sek Men Sains Muzaffar Syah
TUTORIAL 4.1
5.
The diagram shows a metal sphere P at o 80 C is immersed in a cooler liquid Q.
1. Which of the following is true? A. The unit of heat is o C B. Heat is a form of energy C. Heat flows from a cold substance to a hot substance. 2. A boy puts some ice cubes in his orange juice. There is energy transferred between the ice cube and the juice. Which of the following properties determines the direction of such exchange? A. Density B. Temperature C. State of matter D. Specific Heat Capacity
Thermal equilibrium is reached when A. temperature of P = temperature of Q B. mass of Q displaced = mass of P C. volume of Q = volume of P D. specific heat capacity of P = specific heat capacity of Q 6.
3. The diagram shows two bodies P and Q which are in thermal equilibrium.
A. B. C. D.
4.
Which of the following statements is not true? The net rate of heat flow is zero The heat flow in both directions is the same. The final temperature of both bodies is the same. The final physical characteristics of both bodies are the same.
An earth-monitoring satellite falls into the earth’s atmosphere at a high velocity and reaches at the sea surface with a high temperature. After a while the temperature of the satellite is same as the temperature of the sea water. This is caused by A. The heat released by the satellite B. The heat absorbed by the sea water C. The satellite is cooled by the sea water D. The satellite and the sea water are in thermal equilibrium
The diagram shows two copper blocks, L and M, touching each other. The initial o temperatures of L and M are 50 C and o 30 C respectively.
Which statement is correct when L and M are at thermal equilibrium? A. Temperature of L is higher than M B. The quantity of heat in L is the same as in M C. Rate of change in temperature of L is bigger than that of M D. Net rate of heat flow between L and M is zero 7.
The diagram shows object A and object B are of temperatures T1 and T2. The heat flows from A to B until the thermal equilibrium is reached at a temperature T.
Which relationship between T1 , T2 and T is true? A T1 > T2 > T B T2 > T1 > T C T1 > T > T2 D T2 > T > T1
4
Sek Men Sains Muzaffar Syah
8.
What is the concept used in the measurement of human body temperature using a thermometer? (2007) Principle of conservation of temperature A. Specific heat capacity B. Specific latent heat C. Thermal equilibrium D. Thermal convection
9. Which of the following points are used in the calibration of a thermometer? A. Melting point of ice and freezing point of ice. B. Melting point of ice and boiling point of water. C. Boiling point of water and condensation point of water. D. Melting point of ice and condensation point of water. 10. The lengths of the mercury column in a thermometer at the ice point and the steam point are 5 cm and 25 cm respectively. When the thermometer is placed in a liquid , the length of the mercury column is 12 cm. What is the temperature of the liquid? o o A 30 C B 35 C o o C 55 C D 70 C o E 85 C 11. Which liquid A , B, C or D , can be used to make a liquid –in-glass thermometer to o o measure temperatures from -50 C to 50 C? Freezing Boiling o o point / C point / C A -115 78 B -39 357 C 0 100 D 17 118
Which statement is correct about the temperature of the final mixture? (2008) A. It is lower than the temperature of the cold syrup. B. It is lower than the temperature of the hot water C. It is higher than the temperature of the hot water D. It is the same as the temperature of the cold syrup A. B. C. D.
14. The figure shows a mercury thermometer.
(a) Name component P: _______________________ Q: _______________________ (b) (i) State the physical change in the mercury when the temperature increases. __________________________ (ii) Why is mercury used in the thermometer? __________________________ (b)
12. Diagram 12.1 shows hot water being poured into cold syrup. Diagram 12.2 shows the final mixture.
sticks to the glass has a lower boiling point expands and contracts uniformly is transparent and therefore it is easier to read.
The length of the mercury column in the thermometer is 2.6 cm at 0°C and 22.6 cm at 100 °C? (i) What is the difference in the lengths of the mercury columns at 0 °C and at 100 °C? ________________________ (ii) When the thermometer is placed in hot oil, the length of the mercury column is 16.9 cm. Calculate the temperature of the hot oil.
5
Sek Men Sains Muzaffar Syah
SPM 2003 Section C 15. You are representing the country in carrying out a research project on the weather at the North Pole. The surrounding temperature is between o o 40 C to - 8 C. One item of the equipment to be taken for your research is a thermometer. (a) State the principle used in a liquid – glass thermometer. (b) State how a liquid-glass thermometer can be used to measure the body temperature of a sick person. Explain heat transfer that takes place at each stage of measurement.
Additional information: o Freezing point of mercury = -39 C Boliling o point of mercury = 360 C o Freezing point of alcohol = - 112 C Boiling o point of alcohol = 78 C
Based on the table above; (i)
(ii)
(b)
Thermometer
(c) The table shows the characteristics of six types of thermometers P,Q,R,S,T and U. Liquid Glass Diameter Glassused walled of bore bulb capillary stem tube and crosssection P mercury thin big thick and curved
Q
mercury
thick
small
thin and plane
R
mercury
thin
small
thin and curved
S
alcohol
thick
big
thick and plane
T
alcohol
thin
small
thick and curved
U
alcohol
thick
small
thin and plane
Explain the suitable characteristics of the thermometer so that can be used to measure temperatures at the North Pole. Decide which thermometer is most suitable to be taken for your research and give reasons. A thermometer which is not calibrated has a mercury column of length 8.0 cm o when the temperature is 0 C and 20.0 o cm when the temperature is 100 C. The mercury column is 5.0 cm when put in liquid X. (i)
Determine the temperature of liquid X in Kelvin.
(ii) State a thermometric property used when making of a thermometer.
6
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