3 Quantitative chemistry

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Question 14

A student investigated the change in mass when hydrated copper sulfate was heated.

The word equation for the reaction is:

\text{hydrated copper sulfate} \rightleftharpoons \text{anhydrous copper sulfate} + \text{water}

This is the method used:

Add $g2.50\text{ g}$ of hydrated copper sulfate to an empty boiling tube.
Measure the mass of the boiling tube and contents.
Heat the boiling tube and contents gently for 1 minute.
Allow the boiling tube and contents to cool.
Measure the mass of the boiling tube and contents.
Repeat steps 3 to 5 until the mass of the boiling tube and contents does not change.

Table 1 shows the results.

Table 1

Total heating time in minutes	Mass of boiling tube and contents in grams
0	33.70
1	33.25
2	32.80
3	32.80

Questions:

Determine the mass of the empty boiling tube.

[2]

Explain why the mass of the boiling tube and contents decreased.

[2]

Suggest why the boiling tube and contents were heated until the mass did not change.

[1]

When $g249.7\text{ g}$ of hydrated copper sulfate is heated until the mass does not change, $kJ78.5\text{ kJ}$ of energy is taken in. The student heated $g2.50\text{ g}$ of hydrated copper sulfate until the mass did not change. Calculate the energy taken in during this reaction. Give your answer to 3 significant figures.

[2]

What type of reaction, in terms of energy transfer, takes place when hydrated copper sulfate is heated?

[1]

3 Quantitative chemistry

Question 14

A student investigated the change in mass when hydrated copper sulfate was heated.

The word equation for the reaction is:

\text{hydrated copper sulfate} \rightleftharpoons \text{anhydrous copper sulfate} + \text{water}

This is the method used:

Add $g2.50\text{ g}$ of hydrated copper sulfate to an empty boiling tube.
Measure the mass of the boiling tube and contents.
Heat the boiling tube and contents gently for 1 minute.
Allow the boiling tube and contents to cool.
Measure the mass of the boiling tube and contents.
Repeat steps 3 to 5 until the mass of the boiling tube and contents does not change.

Table 1 shows the results.

Table 1

Total heating time in minutes	Mass of boiling tube and contents in grams
0	33.70
1	33.25
2	32.80
3	32.80

Questions:

Determine the mass of the empty boiling tube.

[2]

Explain why the mass of the boiling tube and contents decreased.

[2]

Suggest why the boiling tube and contents were heated until the mass did not change.

[1]

[2]

What type of reaction, in terms of energy transfer, takes place when hydrated copper sulfate is heated?

[1]

3 Quantitative chemistry

Question 14

Table 1

Markscheme

3 Quantitative chemistry

Question 14

Table 1

Markscheme

3 Quantitative chemistry

Question 14

Table 1

3 Quantitative chemistry Questions

3 Quantitative chemistry

Question 14

Table 1

3 Quantitative chemistry Questions