Book 2 Flashcards
If a substance goes through a process that changes its composition so that it is no longer the same substance, then the substance has undergone a:
a. Physical change
b.Heterogeneous change
c. Homogeneous change
d.Chemical change
e.Mechanical change
Chemical change
When is hot oil an ideal heat transfer fluid?
a. when high temperature, high pressure process fluids are needed
b. when glycol is too expensive
c.when low temperature process fluids are needed at high pressure
d.when high temperature process fluids are needed at low pressure
when high temperature process fluids are needed at low pressure
An intensive physical property is one that is:
a.Dependent on the amount of matter
b.Independent of the amount of matter
c.Dependent on the volume
d.Dependent on the density of a substance
e.Dependent on the amount of pressure applied
Independent of the amount of matter
Calculate the boiler efficiency if the heat supplied to the steam is 26 880 kJ per kg of fuel burned and the heating value of 1 kg of fuel is 32 000 kJ.
a.72%
b.78%
c.84%
d.87.7%
e.89.35%
84%
Calculate the heat required to convert 100 kg of water at 35°C into dry saturated steam at a pressure of 1500 kPa (abs).
a.2784.8 kJ
b.5563.4 kJ
c.2781.7 kJ
d.184.09 kJ
e.1.1330 kJ
5563.4 kJ
What is the total enthalpy of 2 kg of dry saturated steam at 1100 kPa abs?
a.2784.8 kJ
b.5563.4 kJ
c.2781.7 kJ
d.184.09 kJ
e.1.1330 kJ
5563.4 kJ
An example of a physical change in matter is the
a.Reaction of sodium with chlorine
b. Boiling of a refrigerant
c.Burning of coal
d.Rusting of steel
e.Corrosion of boiler metal
Boiling of a refrigerant
When the temperature of an object is increased, its change in length is proportional to its:
a.Initial length and initial temperature.
b.Cross-sectional area and temperature.
c.Volume and temperature increase.
d.Initial length and temperature increase
e.Initial temperature, but inversely proportional to its length
Initial length and temperature increase.
If 2460 kJ/kg of heat is added to water at 0°C to produce wet steam at 1500 kPa abs, calculate the dryness fraction.
a.74%
b.64%
c.91%
d.78%
e.83%
83%
How many kJ of heat will be required to convert 65 kg of water at 15°C into saturated steam at 650 kPa abs ?
a.
2697.31
b.
2760.3
c.
62.99
d.
282 329.29
e.
175 325
175 325
Which equation is perfectly balanced?
a.
C2H5OH + 3 O2 → 2 CO2 + 3 H2O
b.
C2H5OH + 4 O2 → 2 CO2 + 3 H2O
c.
C2H5OH + O2 → 2 CO2 + H2O
d.
C2H5OH + O2 → 1 CO2 + H2O
C2H5OH + 3 O2 → 2 CO2 + 3 H2O
An example of a homogenous mixture of solids is:
Select one:
a.
Metal alloy
b.
Soil
c.
Concrete
d.
Plastic
e.
Wood
Metal alloy
When heat flows from molecule to molecule within a substance, or between bodies that are in direct contact, the method of heat transfer is called:
a.
Convection
b.
Induction
c.
Conduction
d.
Contraction
e.
Radiation
Conduction
The amount of heat absorbed by water when it evaporates at atmospheric pressure is
Select one:
a.
99.63 kJ/kg
b.
335 kJ/kg
c.
417.46 kJ/kg
d.
2257 kJ/kg
e.
2675.5 kJ/kg
2257 kJ/kg
Condensation losses in steam can be avoided by:
Select one:
a.
Heating the steam to saturation temperature
b.
Using wet steam
c.
Using only high pressure steam
d.
Installing steam separators
e.
Using superheated steam
Using superheated steam
Which of the following statements is TRUE?
Select one:
a.
In general, coefficients of expansion of solids are greater than those of liquids.
b.
Liquids do not contract when cooled.
c.
The Coefficient of Expansion for a liquid changes if the liquid temperature changes
d.
Solids contract when heated.
e.
Water will only expand when its temperature is increased.
The Coefficient of Expansion for a liquid changes if the liquid temperature changes
What does 1 kilojoule (kJ) equal?
a.
1000 kJ or 103 kJ
b.
1000 J or 103 J
c.
1000 J or 103 kJ
d.
1000 J or 103 J
1000 J or 103 J
Steam containing water particles in suspension is defined as:
Select one:
a.
Dry steam
b.
Theoretical steam
c.
Wet steam
d.
Sub-cooled steam
e.
Superheated steam
Wet steam
Natural convection is a method of heat transfer in which the movement of the fluids is due solely to the:
a.
Surface pressure.
b.
Difference in densities.
c.
Action of a pump or fan.
d.
Gravitational differences.
e.
Activity of the radiant heat
Difference in densities.
In a covalent bond, the valence electrons are ____________ between the atoms.
a.
Repelled
b.
Absent
c.
Loaned
d.
Shared
Shared
Heat that brings about a change of state:
Select one:
a.
Can be sensed by a thermometer
b.
Is called sensible heat
c.
Causes a change of temperature
d.
Is called latent heat
e.
Is called specific heat
Is called latent heat
Large areas, such as warehouses, are usually heated by:
Select one:
a.
Unit heaters
b.
Radiators
c.
Convectors
d.
Open heaters
e.
Space heaters
Unit heaters
A substance that cannot be decomposed into other substances by chemical means is:
Select one:
a.
a Mixture
b.
a Compound
c.
a Solution
d.
an Atom
e.
an Element
an Element
How much heat is in 20 kg of 80% dry steam at 2250 kPa abs?
Select one:
a.
48 573 kJ
b.
55 653 kJ
c.
2781.7 kJ
d.
33,241 kJ
e.
1.1335 MJ
48 573 kJ
Calculate the sensible heat required to raise the temperature of 10 kg of boiler feedwater from 20°C to the boiling point at 300 kPa.
a.
2725.30 kJ
b.
26 413.4 kJ
c.
28 092.6 kJ
d.
2641.34 kJ
26 413.4 kJ
Which of the following statements is true?
Select one:
a.
If there is a temperature difference between a heat source and a cooler object in contact with the source, heat will be transferred to the cooler object.
b.
Heat can be transferred from cold bodies to hot bodies without using an external supply of work.
c.
Specific heat is the same for every substance.
d.
Specific heat capacity is the same for every state of matter of the same substance.
e.
1 J is less than 1 Nm of work.
If there is a temperature difference between a heat source and a cooler object in contact with the source, heat will be transferred to the cooler object.
Radiant heat:
Select one:
a.
Travels in straight lines.
b.
Is present in oil firing but not fuel gas firing.
c.
Radiates through the superheater tube walls.
d.
Radiates through the water in the water walls.
e.
Requires a transfer medium.
Travels in straight lines.
The First Law of Thermodynamics states that heat and work
Select one:
a.
Cannot co-exist
b.
Are mutually convertible
c.
Are unrelated
d.
Are identical
e.
Produce friction
Are mutually convertible
The transfer of heat involving the movement of a fluid is defined as:
Select one:
a.
Conduction
b.
Convection
c.
Radiation
d.
Flux
e.
Thermo-circulation
Convection
The Second Law of Thermodynamics states that, unaided, heat will only flow from a:
Select one:
a.
Cold substance to a hotter substance.
b.
Warm substance to a hotter substance.
c.
Hot substance to a hotter substance.
d.
Region of low heat
e.
Higher temperature body to a lower temperature body.
Higher temperature body to a lower temperature body.
The temperature at which all molecular motion is said to completely cease is:
Select one:
a.
-373°C
b.
0°C
c.
0°F
d.
-460°R
e.
0 K
0 K
25.4 kg of copper at 33°C receives 240 kJ of heat. Calculate the final temperature of the metal.
Select one:
a.
55.454°C
b.
57.353°C
c.
58.353°C
d.
59.756°C
e.
61.243°C
57.353°C
In the First Law of Thermodynamics, heat supplied = increase in internal energy + ____________:
Select one:
a.
Energy supplied.
b.
Energy absorbed.
c.
Work input.
d.
Work done.
e.
Power output.
Work done.
In the Steam Tables, Hg equals:
Select one:
a.
Hf - Hfg
b.
Hf + Hfg
c.
Hf x Hfg
d.
Hf / Hfg
e.
Hf2 + Hfg2
Hf + Hfg
Calculate the heat to be supplied per kilogram of water to produce 80% dry steam at 250 kPa.
a.
1745.2 kJ/kg
b.
17 452 kJ/kg
c.
2173.52 kJ/kg
d.
2726.875 kJ/kg
1745.2 kJ/kg
The information found in Column 8 (labeled Hf)of Table 1 of the Steam Tables is the:
Select one:
a.
Sensible heat
b.
Latent heat
c.
Specific heat
d.
Latent heat of fusion
e.
Latent heat of evaporation
Sensible heat
The second law of thermodynamics states that heat will flow only from a hot substance to what kind of substance?
a.
Warmer
b.
Colder
c.
Exothermic
d.
Endothermic
Colder
Columns 8, 9 and 10 of Table 1 of the Steam Tables, deal with
Select one:
a.
Internal energy
b.
Enthalpy
c.
Entropy
d.
Specific volume
e.
Potential energy
Enthalpy
The total enthalpy of 11 kg of steam at 950 kPa abs is 24 528.713 kJ. Determine the dryness of the steam.
Select one:
a.
0.54
b.
0.64
c.
0.68
d.
0.73
e.
0.87
0.73
What quantity of heat is required to raise the temperature of 2 kgs of copper from 10°C to 60°C if the specific heat of copper is 0.388 kJ/kg°C.
a.
38.8 kJ
b.
38 800 kJ
c.
19.4 J
d.
19.4 kJ
38.8 kJ