  Hess Law Practice Problems

Quiz by Amoi Salmon

Feel free to use or edit a copy

includes Teacher and Student dashboards

### Measure skillsfrom any curriculum

Tag the questions with any skills you have. Your dashboard will track each student's mastery of each skill.

• edit the questions
• save a copy for later
• start a class game
• automatically assign follow-up activities based on students’ scores
• assign as homework
• share a link with colleagues
• print as a bubble sheet

### Our brand new solo games combine with your quiz, on the same screen

Correct quiz answers unlock more play!  10 questions
• Q1
Which of the following is an example of Hess Law?
Calculating the enthalpy change of a reaction by adding the enthalpy changes of two or more reactions.
Finding the molar mass of a substance by measuring its density.
Using stoichiometry to calculate the amount of reactant needed in a reaction.
Determining the equilibrium constant of a reaction by measuring the concentrations of reactants and products.
30s
• Q2
What is the symbol for enthalpy change?
ΔE
ΔS
ΔH
ΔG
30s
• Q3
What does a negative enthalpy change,  ΔH, indicate?
That the reaction is exothermic.
That the reaction does not involve a change in enthalpy.
That the reaction is at equilibrium.
That the reaction is endothermic.
30s
• Q4
What is the enthalpy of reaction for the reverse of a reaction (flipped)?
The negative of the enthalpy of the forward reaction.
The same as the enthalpy of the forward reaction.
Zero.
It cannot be determined.
30s
• Q5
What is the enthalpy of reaction for a reaction that has two or more reaction steps?
The sum of the enthalpy changes of the individual reaction steps.
It cannot be determined.
Zero.
The difference of the enthalpy changes of the individual reaction steps.
30s
• Q6

A + B ----> 2C      ΔH = 50kJ

D+ 2C----> E       ΔH = 25kJ

What is the ΔH of the overall reaction: A+ B + D-----> E ?

100kJ

75kJ

25kJ

50kJ

30s
• Q7

What is the ΔH of the overall reaction: 2A+ 5B ----> 2C + 4D

A + 2B ---> C                 ΔH = -80kJ

A + 3B ---> C + 4D     ΔH = -55kJ

25kJ

135kJ

-25kJ

-135kJ

30s
• Q8

(3) Find the ΔH for the reaction below, given the following reactions and subsequent ΔH values: PCl3(l)  +  Cl2(g)→ PCl5(s)

2PCl3(l)  →  2P(s)  +  3Cl2(g)       ΔH = 640 kJ

2P(s)  +  5Cl2(g) →   2PCl5(s)      ΔH = -886 kJ

123kJ

-123kJ

-246kJ

246kJ

30s
• Q9

Find the ΔH for the reaction below, given the following reactions and subsequent ΔH values: CuCl2(s) + Cu(s)  → 2CuCl(s)

CuCl2(s)     Cu(s)  +  Cl2(g)             ΔH = 206 kJ

2Cu(s) + Cl2(g)  →  2CuCl(s)           ΔH = -136 kJ

342kJ

70kJ

-70kJ

-342kJ

30s
• Q10

What type of reaction is the following reaction and why?

P4(s)  +  6Cl2(g)  →  4PCl3(g)            ΔH = -2439 kJ

Exothermic because ΔH is positive

Endothermic because ΔH is positive

Endothermic because ΔH is negative

Exothermic because ΔH is negative

30s

Teachers give this quiz to your class