Lesson Worksheet: Hess’s Law Chemistry
In this worksheet, we will practice defining and using Hess’s law to calculate enthalpy changes.
Q1:
Consider the enthalpy changes of the following reactions: Calculate the enthalpy of formation of for the given reaction:
- A kJ/mol
- B kJ/mol
- C kJ/mol
- D kJ/mol
Q2:
Consider the 3 reactions shown.
Determine the value of for the following reaction.
- A kJ/mol
- B kJ/mol
- C kJ/mol
- D
Q3:
The algebraic formula for Hessβs law is .
- A
- B
- C
- D
Q4:
The equation shows the formation of one mole of ethanol, , from its constituent elements under standard conditions and with standard states.
| Chemical | Carbon, | Hydrogen, | Ethanol, |
|---|---|---|---|
| Standard Enthalpy of Combustion (kJβ molβ1) |
Given the combustion values in the table, calculate the value for the standard enthalpy of formation.
Q5:
Consider the reactions shown:
What would the value of of the combustion of methane be if formed instead of ?
- A kJ/mol
- B kJ/mol
- C kJ/mol
- D kJ/mol
Q6:
Use the reactions
to calculate for the following reaction:
- A kJ/mol
- B kJ/mol
- C kJ/mol
- D kJ/mol
Q7:
By using the reactions
Calculate which refers to the heat of combustion of nitric oxide for the following reaction:
- A
- B
- C
- D
Q8:
Which of the following values is equivalent to ?
- A
- B
- C
- D
- E
Q9:
Using Hessβs law and the standard enthalpies of combustion in the given table, what is the standard enthalpy of formation of ethane, ?
| Chemical | Carbon, | Hydrogen, | Ethane, |
|---|---|---|---|
| Standard Enthalpy of Combustion, (kJβ molβ1) |
Q10:
Which of the following are necessary to have when calculating the average bond enthalpy of in a molecule of tetrachloromethane, , using Hessβs law?
- Standard enthalpy change of atomization ()
- Standard enthalpy change of atomization ()
- Standard enthalpy change of formation ()
- Standard enthalpy change of formation ()
- Standard enthalpy change of combustion ()
- Standard enthalpy change of combustion ()
- Standard enthalpy change of combustion ()
- A1, 2, and 4
- B4, 5, and 6
- C1, 2, and 7
- D5, 6, and 7
- E2, 3, and 6
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