Some students investigate the rate of corrosion of a steel alloy. They place four identical steel plates in beakers containing sodium chloride (NaCl) solutions of different concentrations.
They measure the mass of each steel plate at the start of the experiment and again after a period of 14 weeks. The table below shows their results:
| Concentration of NaCl solution (wt%) | Mass of steel plate at the start (g) | Mass of steel plate after 14 weeks (g) |
|---|---|---|
| 2.0 | 180.0 | 175.8 |
| 4.0 | 180.0 | 172.1 |
| 8.0 | 180.0 | 167.4 |
| 16.0 | 180.0 | 161.2 |
Determine the following:
Identify the independent variable in this investigation.
Calculate the average loss in mass per week of the steel plate in the 16.0 wt% NaCl solution. Give your answer to 3 significant figures.
Practise OCR GCSE Biology Practical skills with exam-style questions for Foundation and Higher tier. 64 questions, matched to the OCR GCSE Biology (J247) specification and written in the written papers style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.