AQA GCSE · Question 04.3 · Bonding structure and the properties of matter
Describe what happens to the melting point of the solder as the percentage by mass of tin increases. Use data from Figure 5.
How to approach this question
1. Break the graph into two sections. The first section is from 0% tin up to the lowest point on the graph. The second section is from the lowest point up to 100% tin.\n2. For the first section, describe the trend. State the starting percentage and melting point, and the percentage and melting point at the minimum.\n3. For the second section, describe the trend. State the starting percentage and melting point (the minimum) and the final percentage and melting point.\n4. Make sure to quote data points (with units) from the graph to support your description.
Full Answer
As the percentage of tin increases from 0% to about 65%, the melting point decreases from 327°C to 183°C. As the percentage of tin increases further from about 65% to 100%, the melting point increases from 183°C to 232°C.
By analysing the graph, we can describe the trend in two parts:\n1. **From 0% to ~65% tin:** As the percentage of tin increases, the melting point of the solder decreases. It starts at approximately 327°C (for 0% tin, which is pure lead) and drops to a minimum value of about 183°C at around 65% tin.\n2. **From ~65% to 100% tin:** As the percentage of tin increases further, the melting point of the solder increases. It rises from the minimum of 183°C to 232°C at 100% tin (pure tin).
Common mistakes
✗ Only describing one part of the trend (e.g., only saying it decreases).\n✗ Not using any data from the graph to support the description.\n✗ Misreading the scales on the axes.
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