Lecture 2
1-The unit of specific heat is:
a-Cal/ gm.°C
b-J/kg
c- J/cal
d- kelvin
2-The process of measuring the amount of heat released or absorbed in a
chemical reaction" is called...
a-
Calorimetry
b- convection
c- endothermic d- specific heat
3- In an exothermic process …….
a-
heat energy is given out
b- heat energy is given taking in
c- noting happen
4- Barbara pours some 95°C water into a cup of instant noodles. The final
temperature of the mixture is 85°C. If the masses of the hot water and noodles
are 500 g and 150 g respectively, find the specific heat of the noodles. Given that
the original temperature of the noodles is 25°C and the specific heat capacity of
the water is 4 200 J kg-1 °C-1
a- 500.2 J kg-1°C-1
b- 1 076.9 J kg-1 °C-1
c- 2 333.3 J kg-1 °C-1
5- When 0.5 kg water of 80°C is mixed with 0.4 kg water of 20°C, what is the
final temperature of the mixture?
a- 60.5°C
b- 80.0°C
c- 53.3°C
d- 75°C
6- When 0.4 kg water of 70°C is mixed with certain amount of water of 30°C,
the temperature of the final mixture is 45°C. Find the original mass of the
30°C water.
a-0.67 kg
b-0.52 kg
c-0.84 kg
d-1.01 kg
7- “Water has a specific heat capacity of 4 200 J kg–1 °C–1.” According to this
statement, which of the following is correct?
a- 0.5 kg of water needs to absorb 1200 J energy to increase 1°C in temperature.
b- 0.5 kg of water needs to lose 4200 J energy to the surroundings to increase 1°C in
temperature.
c- 1.0 kg of water needs to lose 4 200 J energy to the surroundings to increase 1°C in
temperature.
d- 1.0 kg of water needs to absorb 4 200 J energy to increase 1°C in temperature.
8- Find the energy absorbed by a copper block when the temperature of a 1.5
kg copper block increases from 298 K to 353 K. Given that the specific heat
capacity of copper is 385 J kg–1 °C–1.
a- 30 020 J
b-31 762.5 J
c- 25 896.2 J
d-26 645.2 J
9-In an Endothermic Reaction.....
a-Heat Energy is given out
b-Heat Energy is taken in
c- noting happen
10- Which of the following materials has the lowest specific heat?
a- Ice
b-Water
c- oxygen
d- Copper
11- Find the energy released by a copper block when it is cooled from 100°C
to 20°C. Given that the heat capacity of the block is 770 J °C–1.
a- 770 00 J
b- 86 050 J
c- 61 600 J
d- 50 200 J
12- If 24 062.5 J of energy is absorbed by a copper block when it is heated from
20°C to 45°C, find the mass of the block. Given that the specific heat of copper
is 385 J kg–1 °C–1.
a- 1.2 kg
b- 2.5 kg
c- 3.0 kg
d- 4.4 kg
13- In order to make a cup of milk coffee at 78°C, 200 g of coffee is mixed up
with 40 g of milk. If the original temperature of the coffee is 80°C, find the
original temperature of the milk. Assuming there is no heat lost to the
surroundings. Given that the specific heat capacity of coffee and milk are 4 000
J kg–1 °C–1 and 3 900 J kg–1 °C–1 respectively.
a- 10.26°C
b- 20.65°C
c- 45.21°C
d- 67.74°C
14- What is the energy required to melt a block of 1 kg ice at –10°C completely?
Given that the specific latent heat of fusion of ice is 334 kJ kg–1 and the specific
heat capacity of ice is 2 050 J kg–1 °C–1.
a- 21 500 J
b- 33 200 J
c- 354 500 J
d- 854 000 J
15- If 500 000 J of energy is absorbed by a block of ice when it is heated from
−5°C to 0°C, find the mass of the ice. Given that the specific heat capacity of
ice is 2 050 J kg–1 °C–1 and the specific latent heat of fusion of ice is 334 kJ
kg–1.
a- 1.45 kg
b- 2.56 kg
c- 3.01 kg
d- 3.27 kg
16- We choose copper as the material to make cooking utensils. Which of the
following explanations is / are correct?
a- The melting point of copper is low.
c- Copper has a low specific heat capacity.
b- Copper is a good conductor of heat.
d- b & c
17- John puts some ices in his soft drink. He says that there is an exchange of
energy between the ices and the drink. Which of the following properties
determines the direction of such exchange?
a- Specific heat capacity
b- Density
c- State of matter
d- Temperature
18- The Q of a substance is positive when it undergoes an:
a- Exothermic process
b- Endothermic process
19-How many Joules are in 1 calorie of energy?
a- 4.2 joule
b- 42 joule
c- 14.5 joule
c-both of them
d- 1000 joule
20-The heat capacity of an object depends in part on its ____.
a-mass
b- length
c- specific heat d- only a &c
21-The specific heat of silver is 0.24 J/g°C . How many joules of energy are
needed to warm 4.37 g of silver from 25.0°C to 27.5°C?
a-2.09 joule
b- 3.5 joule
c-17 joule
d- 22 joule
22- Energy needed to change a solid into a liquid without rise in temperature
is
a-latent heat of fusion
b- latent heat of vaporization
c-specific heat
d- heat capacity
23- Convert 2.40 calories to Joules
a-10.08 Joule
b-12.08 Joule
c-4.08 Joule
d-7.02 Joule
24-The heat energy supplied to a liquid to change it into the gaseous state,
without rise in temperature:
a-latent heat of fusion
b- latent heat of vaporization
c-specific heat
d- heat capacity
25-What happens to the temperature of a substance during a phase change?
a- increase
b-decrease c- remains constant
d-none of the above
26- Copper has a specific heat of 0.385 J/(g oC). A piece of copper absorbs 5000
J of energy and undergoes a temperature change from 100oC to 200oC. What is
the mass of the piece of copper?
a-1 gram
b-10 gram
c-100 gram
d-none of the above
27- The amount of energy transfer necessary to raise the temperature of 1 g of
water from 14.5oC to 15.5oC
a-calorie
b-specific heat
d- latent heat d- none of above
28- For a skillet, used for cooking, do you want a high or low specific heat?
a-High, so that it will need more energy to heat up
b-Low, so that it will change temperature quickly
c- no none of the above
28-A reaction is performed in a beaker with a temperature probe recording the
temperature changes of the reaction. If the temperature began at 15.0 degrees
Celsius and ended at 27.5 degrees Celsius.
a-the reaction endothermic
b-the reaction exothermic c-all of the above
29-metal cube at temperature of 10 0C immersed in liquid at temperature 70 0C
What is the temperature of the metal cube when thermal equilibrium is
achieved between the cube and the liquid?
a-Between 10°C and 70°C
b-above 70°C
d-Same as the room temperature
c-less than 10°C
30- the device in which the energy transfer take place called:
a-calorimeter
b- thermometer
c- heater
d- all of the above
31-There are four main processes in changing of phase, and they are:
a-freezing
b- melting
c-condensation d-all of the above
32-Choose the correct characteristics of a solid:
a-Fixed shape and volume
b-Strong forces of attraction between particles
c-atoms only vibrates
d- all of the above
33-What is the difference between liquid and gas in terms of the intermolecular
forces?
a-Liquid has a weaker attractive forces compared to gas
b-Gas almost has no intermolecular forces
c-Liquid has stronger intermolecular forces than solid
d-Both liquid and gas has about the same intermolecular forces
34-Newton's Law of Cooling states that the rate at which an object cools is
proportional to what?
a-Difference in temperature of the object and the temperature of its surroundings
b-Temperature of surroundings
c-Temperature of the object
d-Object's mass
35- Using the Law of Cooling, we can calculate the _____ after a given time.
a. Temperature of the surroundings
b. Temperature of an object after a given time
c. Pressure of an object
d. Volume of an object
36- Sublimation is when a solid transfer directly to a gas
a-
True
b- false
37-What is the difference between condensation and vaporization?
a-They are the same
b-condensation is when solid melts into a liquid, vaporization is when a liquid
freezes into a solid
c-Vaporization is the transition from gas to liquid, condensation is the transition
from liquid to gas
d-Vaporization is the transition from liquid to gas, condensation is the transition
from gas to liquid
38-Melting builds stronger bonds
True
b- false
39-What are the three states of matter?
a-Rock, Brick, Shoe
b-Solid, Liquid, Gas
c- Liquid, Water, Soda
d- Rain, Sleet, Snow
40-………. Is the increase in size of material while …..is the decrease in size
material
a- Expansion, contraction
b- heating and cooling
c- Latent eat and specific eat
d- None of the above