A-Level CIE Chemistry 4.1 Physical Chemistry Practicals: The solubility of hydrated sodiu

Question

The solubility of hydrated sodium sulfate, Na₂SO₄·10H₂O, in water increases with temperature. At a temperature between 25 °C and 70 °C there is a transition and the solubility becomes that of Na₂SO₄. The units of solubility are grams per one hundred grams of water, g/100g water.

An experiment was carried out to investigate this solubility and determine the transition temperature between the two forms of sodium sulfate.

- An empty boiling tube was weighed and the mass recorded.
- Some distilled water was added to the boiling tube and the new mass recorded.
- A small sample of hydrated sodium sulfate was added.
- The boiling tube was carefully heated with stirring until all the solid had dissolved. 
- The apparatus was cooled slowly while constantly stirring and the temperature recorded when the first crystals appeared in the tube.

(a) The results of several of these experiments are recorded below.

Process the results in the table to calculate the solubility, in g/100 g water, of the sodium sulfate for each of the temperatures listed.

Record these values to two decimal places in the additional columns of the table. You may use some or all of the columns.

Label the columns you use.

For each column you use include units where appropriate and an expression to show how your values are calculated.

Use the column headings A to H for these expressions (e.g. A–B).

The solubility of hydrated sodium sulfate, Na₂SO₄·10H₂O, in water increases with temperature - CIE - A-Level Chemistry - Question 2 - 2013 - Paper 1

Worked Solution & Example Answer:The solubility of hydrated sodium sulfate, Na₂SO₄·10H₂O, in water increases with temperature - CIE - A-Level Chemistry - Question 2 - 2013 - Paper 1

mass of boiling tube + solid water / g

mass of boiling tube + water / g

D - C / g

solubility / g / 100 g water

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