Worksheet: Enthalpy Measurements

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


What is the standard enthalpy change for the following reaction? BH()+6HO()2B(OH)()+6H()26232glsg



What is the standard enthalpy change for the following reaction? Give your answer to 1 decimal place. BCl()+3HO()B(OH)()+3HCl()323glsg



What is the standard enthalpy change for the following reaction? BF()+3HO()B(OH)()+3HF()323glsg



When solid ammonium nitrate dissolves in water, the solution becomes cold. This is the basis for an β€œinstant ice pack”:

When 3.21 g of solid NHNO43 dissolves in 50.0 g of water at 24.9∘C in a calorimeter, the temperature decreases to 20.3∘C. Assuming that the water has a specific heat capacity of 4.184/β‹…JgC∘:

Calculate the value of q for this reaction

  • Aβˆ’1,000 J
  • B+1,000 J
  • Cβˆ’960 J
  • D+960 J
  • E+1,000 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


Dissolving 3.0 g of CaCl()2s in 150.0 g of water in a calorimeter at 22.4∘C causes the temperature to rise to 25.8∘C.

What is the approximate amount of heat involved in the dissolution, assuming the heat capacity of the resulting solution is 4.184/β‹…JgC∘?


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. MgCOMgO+COkJmol32Δ𝐻=+118/

  • Aβˆ’176.34 kJ
  • B+78.96 kJ
  • C+176.34 kJ
  • Dβˆ’78.96 kJ

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