Name: ___________________________________________ Date: ________ Period: _____
Part 1: Section Objectives
 Describe temperature and heat flow in terms of the motion of molecules (or atoms).
 Identify chemical processes that either release (exothermic) or absorb (endothermic) thermal
energy.
1. Define energy and explain how energy and heat are related.
2. What is the definition of temperature?
3. What factor affects heat flow?
4. A scientist measures the properties of two samples, A and B. The scientist discovers that the two samples
have the same average kinetic energy. What must be true about samples A & B?
5. What always happens when two objects of different temperatures comes in contact? Give an example
from your own experience (You cannot use my ice cube example!).
6. Two substances in a glass beaker chemically react and the glass beaker becomes too hot to touch. Is this an
endothermic or an exothermic reaction? Explain your answer.
7.
Complete the following table:
Sign of q or H
Heat flows (in/out)
Heat (reactant/product)
Feels to the touch
Exothermic
Endothermic
9. Consider the reaction: Reactants  Products + 43kJ
Is this reaction endothermic or exothermic? Explain your reasoning.
10. CaO + 3C > CaC2 + CO H° = +464.8 kJ
Is this reaction endothermic or exothermic? Explain your reasoning.
1
Part 2: Section Objectives
 Identify methods to measure heat changes.
 Identify chemical processes that either release (exothermic) or absorb (endothermic) thermal
energy.
 Solve problems involving heat flow and temperature changes, using known values of specific heat
and latent heat of phase change.
1. What factors determine the heat capacity of an object?
2. What is the relationship between a Joule and a Calorie?
3. What tool is used to measure heat changes?
4. What is the specific heat equation and what does each of the symbols stand for?
5. Ethanol (l) has a specific heat of 2.44 J/g•oC and mercury’s is 0.14 J/g•oC. Which substance is the easier
one to warm to a higher temperature? Why?
6. On a sunny day, why does the concrete deck around an outdoor swimming pool become hot, while the
water stays cool?
7. The element hydrogen has the highest specific heat of all elements. At room temperature, hydrogen’s
specific heat is 14.30 J/g •°C. If the temperature of a 340.0 g sample of hydrogen is to be raised by 30°C,
how much energy will have to be added to the hydrogen?
2
8. Mercury has one of the lowest specific heats. This fact added to its liquid state at most atmospheric
temperatures makes it effective for use in thermometers. If 257 J of energy are added to 450.0 g of mercury,
the mercury’s temperature will increase by 4.09°C. What is the specific heat of mercury?
9. A 385 g drinking glass is filled with a hot liquid. The liquid transfers 7032 J of energy to the glass. If the
temperature of the glass increases by 22°C, what is the specific heat of the glass?
10. Brass is an alloy made from copper and zinc. A 590.0 g brass candlestick has an initial temperature of
98.0°C. If 2.11x104 J of energy is removed from the candlestick to lower its temperature to 6.8°C, what is
the specific heat of brass?
11. The element radon is at the opposite end of the range, with the lowest specific heat of all naturally
occurring elements. At 25°C, radon’s specific heat is 0.094 J/g•°C. If the temperature of a 35 g sample of
radon is to be lowered by 10°C, how much energy will have to be removed from the radon?
12. A ring with a mass of 25.5 g appears to be pure silver. Rather than test for density, you can confirm the
ring’s composition by determining its specific heat. Suppose the ring is heated to a temperature of 84.0°C
and then immersed in a container of water until the ring’s temperature is 25.0°C. If the ring gives up 667.5
J of energy to the water, what is its specific heat? Is the ring made of silver (C = 0.234 J/g•°C), nickel (C =
0.444 J/g•°C), or palladium (C = 0.244 J/g•°C)?
3
Part 3:Section Objectives
 Solve problems using Hess’s law to calculate enthalpy change in a reaction
 Tutorial: http://www.ausetute.com.au/hesslaw.html
We can use the ∆H for known equations to solve for the ∆H for unknown equations
Manipulate equations
– Reverse the equation, reverse the sign of ∆H
– Multiply the equation, multiply the ∆H
1. From the following enthalpy changes,
C (s) + ½ O2 (g) CO (g)
∆H = -110.5 kJ
CO (g) + ½ O2 (g) CO2 (g) ∆H= -283.0 kJ
calculate the value of ∆H for the reaction C(s) + O2 (g) CO2 (g).
2. From the following enthalpy changes,
Xe (g) + F2 (g) XeF2 (s)
∆H = -123 kJ
Xe (g) + 2F2 (g) XeF4 (s)
∆H = -262 kJ
calculate the value of ∆H for the reaction XeF2 (s) + F2 (g) XeF4 (s).
3. From the following enthalpy changes,
C2H5OH (l) + 3O2 (g) 2CO2 (g) + 3H2O (g)
∆H = -1234.7 kJ
CH3OCH3 (l) + 3O2 (g) 2CO2 (g) + 3H2O (g)
∆H = -1328.3 kJ
calculate the value of ∆H for the reaction C2H5OH (l) CH3OCH3 (l).
4
4. From the following enthalpy changes,
Cu (s) + Cl2 (g) CuCl2 (s)
∆H = -206 kJ
2Cu (s) + Cl2 (g) 2CuCl (s) ∆H = -136 kJ
calculate the value of H for the reaction CuCl2 (s) + Cu (s)  2CuCl (s).
5. From the following enthalpy changes,
H2 (g) + F2 (g) 2HF (g)
∆H = -542.2 kJ
2H2 (g) + O2 (g) 2H2O (l)
∆H = -571.6 kJ
calculate the value of ∆H for the reaction 2F2 (g) + 2H2O (l) 4HF (g) + O2 (g)
6. From the following enthalpy changes,
2P (s) + 3Cl2 (g) 2PCl3 (l)
∆H = -640 kJ
2P (s) + 5Cl2 (g) 2 PCl5 (s) ∆H = -886 kJ
calculate the value of ∆H for the reaction PCl3 (l) + Cl2 (g) PCl5 (s).
5