A student uses a thermometer to measure the temperature of a beaker of water, before and after heating. The smallest thermometer division is 1.0 oC. The initial temperature of the water is 23.0 oC.
A student carries out a thermal decomposition of copper(II) carbonate. The copper(II) carbonate is placed in a pre-weighed crucible and the crucible is weighed again when cool. The reaction that takes place is:
CuCO3 (s) → CuO(s) + CO2 (g)
The results are recorded in the table.
Mass/ + 0.01 g
Mass of empty crucible
38.52 g
Mass of crucible + copper(II) carbonate
46.73 g
Mass of crucible + copper(II) oxide
43.61 g
Calculate the mass of copper(II) oxide formed and determine the percentage uncertainty in the calculated mass.
The student forgets to turn the Bunsen burner, used to heat the crucible, to a blue flame. The yellow, sooty flame, soon coats the outside of the crucible with a black layer.
Identify the black layer and suggest whether the error will have a major or minor effect on their results.
A student analyses a set of results from the determination of the empirical formula of magnesium oxide by burning magnesium ribbon. They plot a graph on the following grid:
The rate of reaction between magnesium and hydrochloric acid was investigated. The concentration of acid was varied and the results plotted on a graph.