Two experiments react the same mass of zinc with dilute sulfuric acid and the volume of hydrogen gas is plotted against time. Curve A (experiment 1) rises steeply at first, then levels off at a final volume of 50 cm3. Curve B (experiment 2) uses a higher temperature than experiment 1, with all other conditions identical; it rises more steeply at the start and levels off at the same final volume of 50 cm3.