Waec Model Questions Vol1 2019 Chemistry Question 8

Practice essay / theory question 8 from the 2019 Waec Model Questions Vol1 Chemistry examination. This question covers solubility, temperature effect, quantitative analysis .

Waec Model Questions Vol1 2019 Chemistry Essay / Theory
Topics: solubility temperature effect quantitative analysis
Question 8 WAEC_MODEL_QUESTIONS_VOL1 • 2019 • CHEMISTRY • essay

A laboratory set‑up is used to determine the solubility of potassium nitrate (KNO₃) in water at different temperatures. The apparatus consists of a thermostatically controlled water bath, a 250 mL beaker, a thermometer, a glass stirring rod and an analytical balance as shown in the labelled diagram. The procedure is carried out at three temperatures and the following data are obtained for the mass of KNO₃ that can dissolve in 100 g of water: • 30 °C : 32 g KNO₃ • 50 °C : 55 g KNO₃ • 70 °C : 86 g KNO₃ Answer the following questions.

Question Parts

( a )
Describe in detail the experimental procedure that should be followed with this apparatus to obtain the solubility data at a chosen temperature.
( b )
Calculate the percentage increase in the solubility of KNO₃ when the temperature is raised from 30 °C to 70 °C.
( c )
If 250 g of water is heated to 70 °C, determine the maximum mass of KNO₃ that can dissolve in it.
( d )
Discuss qualitatively how temperature affects the solubility of most ionic solids such as KNO₃ and relate this to the enthalpy change of dissolution.

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About This Question

This is Waec Model Questions Vol1 2019 Chemistry Question 8. It is one of the essay questions from the 2019 Waec Model Questions Vol1 Chemistry examination.

The question covers solubility, temperature effect, quantitative analysis .

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