Waec Model Questions Vol1 2017 Chemistry Question 6

Practice essay / theory question 6 from the 2017 Waec Model Questions Vol1 Chemistry examination. This question covers States of Matter, Phase changes, Heating curves, Enthalpy, Heat loss .

Waec Model Questions Vol1 2017 Chemistry Essay / Theory
Topics: States of Matter Phase changes Heating curves Enthalpy Heat loss
Question 6 WAEC_MODEL_QUESTIONS_VOL1 • 2017 • CHEMISTRY • essay

A sample of 150.0 g of pure water is initially at 25.0 °C. It is placed in a calorimeter and heated until all the water has been converted to steam at 120.0 °C at a pressure of 1.0 atm.

Question Parts

( a )
Calculate the total amount of heat (in kJ) required for this process. Use cₕ(l) = 4.18 J g⁻¹ K⁻¹, cₕ(g) = 2.01 J g⁻¹ K⁻¹, and assume the molar enthalpy of vaporisation at 120 °C is 38.0 kJ mol⁻¹.
( b )
The calorimeter loses heat to the surroundings at a rate of 5.0 kJ per minute. If the heating process takes 12 minutes, determine the net heat absorbed by the water and discuss how the heat loss would affect the final temperature if the calorimeter were not allowed to reach 120 °C.
( c )
Explain, with reference to intermolecular forces, why the boiling point of water is higher than that of ethanol (C₂H₅OH), even though both have similar molecular weights.

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About This Question

This is Waec Model Questions Vol1 2017 Chemistry Question 6. It is one of the essay questions from the 2017 Waec Model Questions Vol1 Chemistry examination.

The question covers States of Matter, Phase changes, Heating curves, Enthalpy, Heat loss .

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