Edexcel IAL Chemistry AS 7.4.2 Plotting Two Variables

[Maximum number: 3]

Sodium hydroxide can be obtained as a hydrate, $\mathrm{NaOH} \cdot \times \mathrm{H}_{2} \mathrm{O}$ .
When heated, the water of crystallisation is lost, leaving anhydrous sodium hydroxide, NaOH , as shown in the equation.

\mathrm{NaOH} \cdot x \mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{NaOH}+x \mathrm{H}_{2} \mathrm{O}

An experiment was carried out to determine the value of x in $\mathrm{NaOH} \cdot \times \mathrm{H}_{2} \mathrm{O}$ .

Procedure

Step 1 Weigh and record the mass of a clean, dry crucible.
Step 2 Add approximately 1.0 g of $\mathrm{NaOH} \cdot \times \mathrm{H}_{2} \mathrm{O}$ to the crucible and record the mass.
Step 3 Heat the crucible and its contents until a constant mass has been reached.
Step 4 After allowing to cool, reweigh the crucible and the anhydrous solid.
Step 5 Calculate and record the mass of the anhydrous solid.
Repeat Steps 1 to 5 using a different mass of the hydrated sodium hydroxide.

Results

Table for Question Edexcel A-Level Chemistry AS B 3 2 Plotting Two Variables Questions question 1 — Edexcel A-Level Chemistry AS

Complete a graph of the results by
- plotting the points
- labelling the axes
- including a straight line of best fit.

Figure for Question Edexcel A-Level Chemistry AS B 3 2 Plotting Two Variables Questions question 1 — Edexcel A-Level Chemistry AS

six points plotted correctly within a square (1)

- axes labelled including units

(1)

- straight line passing

(1) through all points

Example of graph

Figure for Answer to Question Edexcel A-Level Chemistry AS B 3 2 Plotting Two Variables Questions question 1 — Edexcel A-Level Chemistry AS

Mass of $\mathrm{NaOH} \cdot \times \mathrm{H}_{2} \mathrm{O}$ / g

Allow line of best fit going through 0,0

Allow axes reversed.

Allow "(g)" instead of "/ g" for units

Edexcel A-Level Chemistry AS B 3 2 Plotting Two Variables Questions question 1