A company wants a solid for a cold pack. The solid must give the biggest temperature decrease for each gram used.
A scientist adds four solids, W, X, Y and Z, to separate 50 cm350\,\mathrm{cm^{3}}50cm3 portions of the same solution. The solution is in excess each time.
| Solid | Mass of solid (g) | Temperature change (∘C^\circ\mathrm{C}∘C) |
|---|---|---|
| W | 10.0 | -6.0 |
| X | 4.0 | -3.2 |
| Y | 5.0 | +7.0 |
| Z | 8.0 | -5.6 |
Which solid should the company choose?
W
X
Y
Z
51 exam-style questions on OCR GCSE Chemistry 3.2 Energetics, covering 3.2.1 Exothermic and endothermic reactions and reaction profiles and 3.2.2 Calculating energy change from bond energies. Each one has a worked solution and a mark scheme showing where the marks go.