The lumps and powder graph
Equal masses of calcium carbonate, as lumps and as powder, were each reacted separately with equal volumes of dilute hydrochloric acid. The time taken and the mass of CaCO3 lost are given in the table below.
| Time (minutes) | Lumps — mass lost (g) | Powder — mass lost (g) |
|---|---|---|
| 1 | 2.1 | 3.1 |
| 2 | 2.9 | 4.0 |
| 3 | 3.5 | 4.4 |
| 4 | 3.9 | 4.6 |
| 5 | 4.2 | 4.7 |
| 6 | 4.4 | 4.8 |
| 7 | 4.5 | 4.8 |
| 8 | 4.6 | 4.8 |
| 9 | 4.7 | 4.8 |
| 10 | 4.8 | 4.8 |
| 11 | 4.8 | 4.8 |
| 12 | 4.8 | 4.8 |
Both cases on one pair of axes
| t (min) | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| m (g) | 0 | 3.1 | 4 | 4.4 | 4.6 | 4.7 | 4.8 | 4.8 | 4.8 | 4.8 | 4.8 | 4.8 | 4.8 |
Solid line — powder. Dashed line — lumps.
The table holds 24 numbers; the graph holds the same 24. But the graph shows at a glance something the table does not — the shape of the two curves.