# Worksheet: Enthalpy Measurements

In this worksheet, we will practice using calorimetry data to determine enthalpy changes during phase changes and chemical reactions.

Q1:

What is the standard enthalpy change for the following reaction?

 Substance Ξπ»β¦΅f(kJ/mol) BH()26g HO()2l B(OH)()3s H()2g 36.4 β285.83 β1,094.33 0

Q2:

What is the standard enthalpy change for the following reaction? Give your answer to 1 decimal place.

 Substance Ξπ»(/)β¦΅fkJmol BCl()3g HO()2l B(OH)()3s HCl()g β403.8 β285.83 β1,094.33 β92.307

Q3:

What is the standard enthalpy change for the following reaction?

 Substance Ξπ»β¦΅f(kJ/mol) BF()3g HO()2l B(OH)()3s HF()g β1,136.0 β285.83 β1,094.33 β273.3

Q4:

When solid ammonium nitrate dissolves in water, the solution becomes cold. This is the basis for an βinstant ice packβ:

When 3.21 g of solid dissolves in 50.0 g of water at in a calorimeter, the temperature decreases to . Assuming that the water has a specific heat capacity of :

Calculate the value of q for this reaction

• A J
• B J
• C J
• D J
• E J

What is the molar enthalpy for the dissolution of ammonium nitrate in water?

• A52 kJ/mol
• B22 kJ/mol
• C19 kJ/mol
• D26 kJ/mol
• E35 kJ/mol

Q5:

Dissolving 3.0 g of in 150.0 g of water in a calorimeter at causes the temperature to rise to .

What is the approximate amount of heat involved in the dissolution, assuming the heat capacity of the resulting solution is ?

Q6:

Calculate, to 2 decimal places, the enthalpy change produced from the thermal decomposition of 126 g of magnesium carbonate, its molar mass is 84.313 g/mol, under constant pressure according to the given equation.

• A kJ
• B kJ
• C kJ
• D kJ