Neco 2020 Chemistry Question 6

Practice essay / theory question 6 from the 2020 Neco Chemistry examination. This question covers States of Matter .

Neco 2020 Chemistry Essay / Theory

Topic: States of Matter

Question 6 NECO • 2020 • CHEMISTRY • essay

A 2.00 g sample of a pure substance (molar mass = 80.0 g·mol⁻¹) is heated in a calorimeter. The substance has a melting point of 20°C and a boiling point of 100°C. Its specific heat capacities are: solid = 0.45 J·g⁻¹·K⁻¹, liquid = 0.80 J·g⁻¹·K⁻¹, gas = 1.04 J·g⁻¹·K⁻¹. The enthalpy of fusion is 12.0 kJ·mol⁻¹ and the enthalpy of vaporisation is 30.0 kJ·mol⁻¹. The sample is initially at –20°C and is heated until it reaches 150°C.\n\nAnswer the following:

Question Parts

( a )

Calculate the amount of heat (in joules) required for each of the following stages:\n(i) heating the solid from –20°C to its melting point,\n(ii) melting the solid,\n(iii) heating the liquid from the melting point to the boiling point,\n(iv) vaporising the liquid, and\n(v) heating the gas from the boiling point to 150°C.

( b )

Determine the total heat absorbed by the sample to reach 150°C.

( c )

Briefly describe the changes in molecular arrangement and motion that occur in the substance during each of the five stages listed in part (a).

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About This Question

This is Neco 2020 Chemistry Question 6. It is one of the essay questions from the 2020 Neco Chemistry examination.

The question covers States of Matter .

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