# Worksheet: Molar Energy Units

In this worksheet, we will practice using Avogadro's number to convert between molar energies and the energies of single bonds.

Q1:

The molar bond energy of is 159 kJ/mol. Calculate the energy of one bond.

• A J
• B J
• C J
• D J
• E J

Q2:

What is Avogadro’s number to 3 significant figures?

• A
• B
• C
• D3.14
• E

Q3:

3.70 mol of bonds release 888 kJ of energy when they form. How much energy is released when bonds form?

• A J
• B J
• C J
• D J
• E J

Q4:

Which of the following quantities of bonds requires the most energy to break?

• A
• B
• C
• D
• E

Q5:

Every molecule of iodine, , has an iodine–iodine bond, . The energy required to break one of these bonds is J. How much energy is required to break 1.00 mole of these bonds?

• A J
• B J
• C J
• D J
• E J

Q6:

The energy of the hydrogen–hydrogen bond in is 436 kJ/mol. Which of the following is an equivalent description of the bond energy in hydrogen?

• A436 kJ of energy is required to form the hydrogen–hydrogen bonds of hydrogen molecules.
• BFor every hydrogen–hydrogen bond in a hydrogen molecule formed, 436 kJ of energy is released.
• C436 kJ of energy is released when the hydrogen–hydrogen bonds of hydrogen molecules are broken.
• DFor every hydrogen–hydrogen bond in a hydrogen molecule broken, 436 kJ of energy is released.
• E436 kJ of energy is required to break the hydrogen–hydrogen bonds of hydrogen molecules.

Q7:

What is the SI unit for energy?

• AJoule (J)
• BMole (mol)
• CWatt (W)
• DKilogram (kg)
• EElectron volt (eV)

Q8:

The specific heat capacity of a substance is usually given in units of joules per gram per degree Celsius. From these units, which of the following statements best describes specific heat capacity?

• AThe amount of energy needed to raise the temperature of 1 gram of a substance by
• BThe temperature of a substance that is equal to the amount of energy multiplied by its mass
• CThe amount of substance that can be produced when one joule of energy is raised by
• DThe amount of energy formed when 1 gram of a substance reaches a specific temperature
• EThe mass of a substance needed to raise the temperature by

Q9:

A single bond has an energy of . What is the molar bond energy for ? Give your answer to the nearest whole number.

Q10:

It takes approximately J of energy to break all the bonds in a single molecule of methane, . What is the average molar bond energy for bonds? Give your answer to the nearest whole number.

Q11:

4.6 g of a fuel is found to produce J of heat energy. If the of the fuel is 46 g/mol, what is the molar enthalpy change?

• A kJ/mol
• B kJ/mol
• C kJ/mol
• D kJ/mol
• E kJ/mol

Q12:

Which of the following are units for the molar enthalpy change of a reaction, ?

• Amol/dm3
• B/atom
• CkJ/mol
• Dcm3/s
• Eg/mol

Q13:

It is estimated that the average adult should consume around 2,000 kcal per day to maintain a healthy lifestyle. What is this value in units of kilojoules?

Q14:

A food manufacturer determines that the energy content of one slice of their new bread is 400 kJ. What value is this in kilocalories? Give your answer to 1 decimal place.

Q15:

A chocolate bar is found to contain 228 kcal. What value is this in units of kilojoules? Give your answer to the nearest whole number.