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Worksheet Calculations involving Specific Heat, Exercises of Chemical Thermodynamics

8 questions in this worksheet with answers. Each question also ask if the reaction is endothermic or exothermic?

Typology: Exercises

2020/2021

Uploaded on 04/20/2021

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Worksheet- Calculations involving Specific Heat
1. For q= m c Δ T : identify each variables by name & the units associated with it.
q = amount of heat (J)
m = mass (grams)
c = specific heat (J/g°C)
ΔT = change in temperature (°C)
2. Heat is not the same as temperature, yet they are related. Explain how they differ from each other.
Heat is a combination of kinetic energy (measured by temperature) and potential energy.
a. Perform calculations using: (
q= m
c
Δ T) b. Determine if it’s endothermic or exothermic
1. Gold has a specific heat of 0.129 J/(g×°C). How
many joules of heat energy are required to raise
the temperature of 15 grams of gold from 22 °C to 85
°C?
q = ?
m = 15 g
c = 0.129 J/g°C
ΔT = 85°C - 22°C = 63°C
q = mc ΔT
q = (15 g)(0.129 J/g°C)(63 °C)
q = 121.9 J 120 J
Endothermic or exothermic? Endothermic
2. An unknown substance with a mass of 100 grams
absorbs 1000 J while undergoing a temperature increase
of 15 °C. What is the specific heat of the substance?
q = 1000 J
m = 100 g
c = ?
ΔT = 15°C
c = 0.666667 J/g°C 0.7 J/g°C
Endothermic or exothermic? Endothermic
3. If the temperature of 34.4 g of ethanol increases
from 25 °C to 78.8 °C, how much heat has been absorbed
by the ethanol? The specific heat of ethanol is 2.44
J/(g×°C)
q = ?
m = 34.4 g
c = 2.44 J/g°C
ΔT = 78.8°C - 25°C = 53.8°C 54 °C
q = (34.4 g)(2.44 J/g°C)(54 °C)
q = 4532.544 J 4500 J
Endothermic or exothermic? Endothermic
4. Graphite has a specific heat of 0.709 J/(g×°C). If a
25 gram piece of graphite is cooled from 35 °C to 18 °C,
how much energy was lost by the graphite?
q = ?
m = 25 g
c = 0.709 J/g°C
ΔT = 18°C - 35°C = -17°C
q = (25 g)(0.709 J/g°C)(-17 °C)
q = --301.325 J -300 J
Endothermic or exothermic? Exothermic
5. Copper has a specific heat of 0.385 J/(g×°C). A piece
of copper absorbs 5000 J of energy and
undergoes a temperature change from 100 °C to
200 °C. What is the mass of the piece of copper?
q = 5000 J
m = ?
c = 0.385 J/g°C
ΔT = 200°C - 100°C = 100°C
m= 129.87 g 100 g
Endothermic or exothermic? Endothermic
6. 45 grams of an unknown substance undergoes a
temperature increase of 38 °C after absorbing
4172.4 Joules. What is the specific heat of the
substance? Look at the table on page 513 of your
book, and identify the substance.
q = 4172.4 J
m = 45 g
c = ?
ΔT = 38°C
c = 2.44 J/g°C 2.4 J/g°C Ethanol
Endothermic or exothermic? Endothermic
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1. For q= m ●c ● Δ T : identify each variables by Worksheet-^ Calculations involving Specific Heat c = specific heat (J/g q = amount of heat (J) m = mass (grams) name & the units°C associated with it).

  1. a. (^) Heat is not the same as temperature, yet they are related. Heat is a combination of kinetic energy (measured by temperature) and potential energy. Perform calculations using: ( q= m ●^ ΔT = change in temperature ( c ● Δ T) b. Determine if it’s endothermic or exothermic Explain how the°C) y differ from each other.
    1. many joules of heat energy are required to raise the temperature of 15 grams of gold from 22 ° q = ?C? Gold has a specific heat of 0.129 J/(g×°C). How °C to 85 m = 15 g c = 0.129 J/g ΔT = 85 q = mc ΔT°C - 22 °C°C = 63°C q = (15 g)(0.129 J/g q = 121.9 J Endothermic  or exothermic? 120 J °C)(63 °C ) Endothermic
      1. absorbs 1000 J while undergoing a temperature increase of 15 q = 1000 J m = 100 g An unknown substance with a mass of 100 grams °C. What is the specific heat of the substance? c =? ΔT = 15°C
    2. from If the temperature of 25 °C to 78.8 °C, how much heat has been absorbed 34.4 g of ethanol increases^ c = 0.666667 J/g^ Endothermic or exothermic?°C^ ^ 0.7 J/g°C^ Endothermic by the ethanol? J/(g q = m = c = ?2.4434.4×°C) J/gg °C The specific heat of ethanol is 2. ΔT = q = ( q = 4532.54434.4 78.8 g)(°C2.44 - J (^2 5)  °CJ/g 4500 = (^) °C53.8)( (^54) J °C °C ) 54 °C Endothermic or exothermic? Endothermic
      1. 25 gram piece of graphite is co how much energy was lost by the graphite? q = m = Graphite has a specific heat of 0.709 J/(g? 2 5 g oled from 35 °×°C to 18C). If a °C, c = ΔT = q = ( q = 0.709-- (^2) 301.325 (^18) 5 g)(0.°C J/g - 70935 °CJ°C J/g = - - (^17) °C 300 J °C)(- 17 °C)
    3. of copper absorbs 5000 J of energy and undergoes a temperature change from 100 200 Copper has a specific heat of °C. What is the mass of the piece of copper? 0.385 J/(g °×°C toC). A piece^ Endothermic or exothermic?^ Exothermic q = m = c = 0. ΔT = 5000 J? 385200 °CJ/g - °C 100 °C = 100 °C m Endothermic or exothermic?= 129.87 g  100 g Endothermic
      1. temperature increase of 38 4172.4 Joules. What is the specific heat of the substance? book, and identify the substance. 45 grams of an unknown substance undergoes a Look at the table on pa °C after absorbing ge 513 of your q = m = c = ΔT = 4172.4 J? 4 5 g 38 °C c = Endothermic or exothermic? 2.44 J/g°C  2.4 J/g°C (^) EndothermicEthanol
  1. How much did the water temperature change specific heat of water is 4.18 J/(g q = m = A 500 J 40 40 g g sample of water absorbs 500 Joul×°C). es of energy.? The c = 4.18 ΔT =? J/g°C Endothermic or exothermic?^ =^ 2.99 °C^ ^ 3°C Endothermic
    1. what is the final temperature of the water? Liquid water has a specific heat of 4.18 J/(g q = m = If 335 g of water at 65.5 - 335 9750 J g °C loses 9750 J of heat,×°C). c = ΔT = 4.18 Tfinal J/g – °C65.5 °C

2. Endothermic or exothermic?^ Exothermic