Question 19N.3.sl.TZ0.c(i)
| Date | November 2019 | Marks available | [Maximum mark: 1] | Reference code | 19N.3.sl.TZ0.c(i) |
| Level | sl | Paper | 3 | Time zone | TZ0 |
| Command term | Justify | Question number | c(i) | Adapted from | N/A |
A student investigated how the type of acid in acid deposition affects limestone, a building material mainly composed of calcium carbonate.
The student monitored the mass of six similarly sized pieces of limestone. Three were placed in beakers containing 200.0 cm3 of 0.100 mol dm−3 nitric acid, HNO3 (aq), and the other three in 200.0 cm3 of 0.100 mol dm−3 sulfuric acid, H2SO4 (aq).
The limestone was removed from the acid, washed, dried with a paper towel and weighed every day at the same time and then replaced in the beakers.
The student plotted the mass of one of the pieces of limestone placed in nitric acid against time.
[Source: © International Baccalaureate Organization 2019]
The student hypothesized that sulfuric acid would cause a larger mass loss than nitric acid.
Justify this hypothesis.
[1]
sulfuric acid is diprotic/contains two H+ «while nitric acid contains one H+»/releases more H+ «so reacts with more limestone»
OR
higher concentration of protons/H+ ✔
NOTE: Ignore any reference to the relative strengths of sulfuric acid and nitric acid.
Accept “sulfuric acid has two hydrogens «whereas nitric has one»”.
Accept "dibasic" for "diprotic".
