When a 6.50-g sample of solid sodium hydroxide dissolves in 100.0 g of water in a coffee-cup calorimeter, the temperature rises from 21.6 degrees C to 37.8 degrees C. Calculate delta H (in kJ/mol NaOH) for the solution process. Assume that the specific heat of the solution is the same as that of pure water.

Question

Chemistry

Shane Hurst

24 November, 09:57

When a 6.50-g sample of solid sodium hydroxide dissolves in 100.0 g of water in a coffee-cup calorimeter, the temperature rises from 21.6 degrees C to 37.8 degrees C. Calculate delta H (in kJ/mol NaOH) for the solution process. Assume that the specific heat of the solution is the same as that of pure water.

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Answers (1)

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Kale Chapman · Answer 1

Total mass = 100 + 6.5 = 106.5 g

Specific heat of water = 4.18 Joules/gram °C

Q = mCpΔT

Q = 106.5 x 4.18 x (37.8 - 21.6)

Q = 7177 Joules

Moles of NaOH:

6.5 / (23 + 16 + 1)

= 0.1625

Enthalpy of reaction: 7177/0.1625

= 441.7 kJ/mol NaOH