A leisure centre is comparing paper towels with an electric hand dryer. The data are for drying hands 100 000 times.
| Life-cycle data | Paper towels | Electric hand dryer |
|---|---|---|
| Energy used to obtain raw materials and manufacture the products (MJ) | 6200 | 1800 |
| Energy used during each 10 000 hand dries (MJ) | 0 | 210 |
| Water used to obtain raw materials and manufacture the products (dm3\mathrm{dm^{3}}dm3) | 12 000 | 2400 |
| Mass of material sent for disposal (kg) | 420 | 22 |
Which conclusion is supported by the data?
The electric hand dryer uses less energy in total, uses less water to obtain raw materials and manufacture the product, and sends less mass for disposal.
The paper towels use less energy in total, although their production uses more water and sends more mass for disposal.
The electric hand dryer uses less energy in total, but its production uses more water than the paper towels.
The electric hand dryer uses more energy in total, but sends less mass for disposal than the paper towels.
136 exam-style questions on OCR GCSE Chemistry 6.1 Improving processes and products, covering 6.1.1 Extracting metals industrially and by electrolysis, 6.1.2 Life cycle assessment and recycling, 6.1.3 Biological methods of metal extraction, 6.1.4 The Haber process and the production of fertilisers, 6.1.5 Alloys and their uses, 6.1.6 Corrosion and its prevention, 6.1.7 Comparing and selecting materials, and 6.1.8 Industrial conditions, rate and position of equilibrium. Each one has a worked solution and a mark scheme showing where the marks go.