Chemistry 9701/22 — May/June 2015
Cambridge AS Level · AS Level Structured Questions · worked solutions for every part, with the mark scheme
Topics Atoms, Molecules and Stoichiometry · Electrochemistry · Chemical Energetics · Atomic Structure · Chemical Periodicity · Equilibria · +6 more
Chemists recognise that atoms are made of three types of particle.
Complete the following table with their names and properties.
| name of particle | relative mass | relative charge |
|---|---|---|
| +1 | ||
| 1/1836 | ||
Most elements exist naturally as a mixture of isotopes, each with their own relative isotopic mass. The mass spectrum of an element reveals the abundances of these isotopes, which can be used to calculate the relative atomic mass of the element.
Magnesium has three stable isotopes. Information about two of these isotopes is given.
| isotope | relative isotopic mass | percentage abundance |
|---|---|---|
| 24.0 | 79.0 | |
| 26.0 | 11.0 |
Define the term relative isotopic mass.
The relative atomic mass of magnesium is 24.3.
Calculate the percentage abundance and hence the relative isotopic mass of the third isotope of magnesium. Give your answer to three significant figures.
Magnesium can be produced by electrolysis of magnesium chloride in a molten mixture of salts.
Give equations for the anode and cathode reactions during the electrolysis of molten magnesium chloride, .
anode
cathode
The electrolysis is carried out under an atmosphere of hydrogen chloride gas to convert any magnesium oxide impurity into magnesium chloride.
An investigation of the reaction between magnesium oxide and hydrogen chloride gas showed that an intermediate product was formed with the composition by mass Mg, 31.65%; O, 20.84%; H, 1.31% and , 46.20%.
Calculate the empirical formula of this intermediate compound.
The acid/base behaviour of the oxides in the third period varies across the period.
Describe this behaviour and explain it with reference to the structure and bonding of sodium oxide, , aluminium oxide, , and sulfur trioxide, .
Write equations for reactions of these three oxides with hydrochloric acid and/or sodium hydroxide as appropriate.
The rest of this paper
3 more questions- Q2Atoms, Molecules and Stoichiometry · Electrochemistry · Equilibria · Reaction Kinetics · Chemical Energetics · Nitrogen and Sulfur18M
- Q3Chemical Energetics · Hydrocarbons · Halogen Compounds13M
- Q4Introduction to Organic Chemistry · Carbonyl Compounds11M