Practice Paper 2 (Cambridge International AS Chemistry)

The species Cl⁻, K⁺ and Ar are isoelectronic. This means that they have the same number of electrons.

Which row gives the correct order of ionic radii from largest to smallest?

Which statement describes the nuclei of different isotopes of the same element?

Which statement describes a free radical?

The table gives the successive ionisation energies for an element R.

What is the oxidation state of element R in its chloride?

Complete Table 3.1 to show the composition of the given species.

Table 3.1

Beams of protons, neutrons and electrons behave differently in an electric field.

Fig. 3.1 shows the path of a beam of protons in an electric field.

On Fig. 3.1, draw and label the paths of a beam of electrons and a beam of neutrons.

Fig. 3.1

Chlorine and sulfur are elements in Period 3.

Explain why the atomic radius of a chlorine atom is smaller than that of a sulfur atom.

Atoms are made up of three subatomic particles: protons, neutrons and electrons.

Table 2.1 shows data about these particles.

Table 2.1

Calculate the mass of one atom of carbon-12, ¹²C, in kg.

Show your working.

A sample of carbon contains three isotopes, ¹²C, ¹³C and ¹⁴C.

State one similarity and one difference in the properties of these isotopes of carbon. Explain your answer.

A sample of element E contains five isotopes. The percentage abundance of four of the isotopes is shown in Table 2.2.

Table 2.2

i) Calculate the percentage abundance of ⁴⁹E.

ii) Calculate the relative atomic mass, A_r, of element E. Give your answer to one decimal place. Show your working.

iii) Identify element E.

Complete Table 1.1 to show the composition of the given species.

Table 1.1

Lithium and potassium are Group 1 metals.

State the isotopic symbol and the full electronic configuration for a potassium ion, K⁺, with a nucleon number of 39.

symbol .......................................................................

electronic configuration .............................................................................

Beams of protons, neutrons and electrons behave differently in an electric field due to their differing properties. Fig. 1.1 shows the path of a beam of electrons in an electric field.

On Fig. 1.1, draw and label the paths of a beam of protons and a beam of neutrons in the same field.

Fig. 1.1

Table 1.2 shows the 5th to 8th successive ionisation energies of three elements, X, Y and Z, which are in Period 3 of the Periodic Table.

Table 1.2

i) Deduce the group of the Periodic Table to which element Y belongs. Explain your answer.

Group ...............................

Explanation ..............................

ii) State and explain the general trend in first ionisation energies across Period 3.

iii) Explain why the first ionisation energy of element Y is less than that of element X.

iv) Complete the full electronic configuration of an atom of element Z.

1s² .................

An element, X, has a relative atomic mass of A_r and exists as a diatomic molecule, X₂.

Which expression represents the total number of atoms present in m grams of the gas?

(Where L represents the Avogadro constant.)

What is the mass of 0.56 moles of potassium dichromate (VI), K₂Cr₂O₇?

Hydrated copper(II) sulfate, CuSO₄∙ x*H₂O, has a relative formula mass of 231.6.

What is the value of x?

A volume of nitrogen gas, 2.00 dm³ measured at room temperature and pressure (r.t.p.), was reacted with a large volume of hydrogen gas to produce ammonia. Only 15.0% of the nitrogen gas reacted to produce ammonia.

What mass of ammonia was produced?

Nitrous oxide is used as a sedative in dentistry and has the formula N₂O. Different sources of N₂O contain different ratios of ¹⁴N and ¹⁵N.

State the name of the instrument used to distinguish between ¹⁴N and ¹⁵N and outline two characteristic differences seen in the analysis of ¹⁴N and ¹⁵N.

Extract:

Nitrous oxide is used as a sedative in dentistry and has the formula N2O. Different sources of N2O contain different ratios of ^14^N and ^15^N.

A sample of nitrous oxide was enriched so that it contained 4% by mass of ¹⁵N. Calculate the relative molecular mass of the resulting nitrous oxide.

An atom has twice as many protons, and twice as many neutrons, as an atom of ¹⁵N.

Determine the chemical symbol for this atom, including the mass number, and deduce the number of electrons.

Apatite is a general term used for a family of various calcium phosphate compounds commonly found in rocks and minerals, bones and teeth.

i) State the formula of calcium phosphate.

ii) Hydroxylapatite, Ca₅(PO₄)₃OH, is one member of the apatite family and is a major component of bone.

Give the oxidation number of calcium in hydroxyapatite. Explain your answer.

iii) Another member of the apatite family is chlorapatite.

Suggest the formula of chlorapatite.

Fluorapatite, Ca₅(PO₄)₃F, reacts with sulfuric acid to form hydrogen phosphate, calcium sulfate and hydrogen fluoride.

Write the balanced chemical equation for this reaction.

Fluorapatite, Ca₅(PO₄)₃F, can also react with sulfuric acid to form calcium dihydrogenphosphate, Ca(H₂PO₄)₂, calcium sulfate and hydrogen fluoride.

2Ca₅(PO₄)₃F + 7H₂SO₄ → 3Ca(H₂PO₄)₂ + 7CaSO₄ + 2HF

Calculate the mass of calcium dihydrogenphosphate formed when 50.2 g of Ca₅(PO₄)₃F reacts with 87.9 g H₂SO₄.

mass of Ca(H₂PO₄)₂ = ............................ g

This question is about the reactions of ionic compounds.

Sodium carbonate is manufactured in a two-stage process as shown.

NaCl + NH₃ + CO₂ + H₂O → NaHCO₃ + NH₄Cl

2NaHCO₃ → Na₂CO₃ + H₂O + CO₂

Calculate the maximum mass of sodium carbonate that can be obtained from 0.75 kg of sodium chloride.

Show your working.

Norgessaltpeter, Ca(NO₃)₂, was the first nitrogen fertiliser to be manufactured in Norway. It is produced by the reaction of calcium carbonate with nitric acid.

In an experiment, an excess of powdered calcium carbonate was added to 37.4 cm³ of 0.531 mol dm^–3 nitric acid.

Calculate the minimum mass of CaCO₃ that should be added to react with all of the nitric acid. Give your answer to an appropriate number of significant figures.

Show your working.

A 0.0830 mol sample of pure zinc oxide was added to 75.0 cm³ of 0.90 mol dm⁻³ hydrochloric acid.

Assuming the reaction has a percentage yield of 60.6%, calculate the mass of anhydrous zinc chloride that could be obtained from the products of this reaction.

Show your working.

Magnesium nitride, Mg₃N₂, reacts with water to form magnesium hydroxide and ammonia.

Calculate the number of molecules of ammonia gas produced by the reaction of 12.62 g of magnesium nitride.

Show your working.

Which statement correctly describes the relationship between electronegativity difference and bond type?

Which compound does not contain ionic bonds?

Which metal has the highest electrical conductivity?

Which bond is the shortest?

What is the bond angle in a trigonal planar molecule?

Which molecule has the largest dipole moment?

Which statement about 2-chloropropene, CH₂=C(Cl)CH₃, is not correct?

The electronegativities of some elements are shown in Table 3.1.

Table 3.1

Define the term electronegativity.

Extract:

The electronegativities of some elements are shown in Table 3.1.

Table 3.1

Use Table 3.1 to explain the trend in electronegativity across a period of the Periodic Table.

Extract:

The electronegativities of some elements are shown in Table 3.1.

Table 3.1

Explain how the carbon-hydrogen bond (such as in CH₄) differs from the nitrogen-hydrogen bond (such as in NH₃) in terms of the bond polarity.

Extract:

The electronegativities of some elements are shown in Table 3.1.

Table 3.1

Explain, in terms of electronegativity, why the bonding in ammonia (NH₃) is covalent but the bonding in lithium chloride (LiCl) is ionic.