Neco 2019 Chemistry Question 6

Practice essay / theory question 6 from the 2019 Neco Chemistry examination. This question covers States of Matter .

Neco 2019 Chemistry Essay / Theory

Topic: States of Matter

Question 6 NECO • 2019 • CHEMISTRY • essay

A 5.0 g sample of a pure substance X is initially a solid at 25\(^\circ\)C. The substance has the following data: - Melting point: 150\(^\circ\)C, \(\Delta H_{fus}=60\) kJ kg\(^{-1}\) - Boiling point: 300\(^\circ\)C, \(\Delta H_{vap}=200\) kJ kg\(^{-1}\) - Specific heat capacities: \(c_{solid}=0.9\) J g\(^{-1}\)K\(^{-1}\), \(c_{liquid}=1.2\) J g\(^{-1}\)K\(^{-1}\), \(c_{gas}=0.7\) J g\(^{-1}\)K\(^{-1}\) The sample is heated uniformly until it reaches 350\(^\circ\)C. Calculate the total amount of heat energy (in kJ) required for the entire process. Show all steps and state any assumptions made.

( a )

Calculate the energy needed to raise the temperature of solid X from 25\(^\circ\)C to its melting point (150\(^\circ\)C).

( b )

Determine the heat required for the complete melting of the 5.0 g sample.

( c )

Calculate the energy needed to raise the temperature of liquid X from 150\(^\circ\)C to its boiling point (300\(^\circ\)C).

( d )

Determine the heat required for the complete vaporisation of the 5.0 g sample at 300\(^\circ\)C.

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This is Neco 2019 Chemistry Question 6. It is one of the essay questions from the 2019 Neco Chemistry examination.

The question covers States of Matter .

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