Crystal structures and physical properties

This question is about vanadium and some of its compounds.

State the block in the Periodic Table that contains vanadium.

Suggest why vanadium can be pulled into thin wires.

Vanadium(V) oxide is a catalyst in the Contact process.

Give two equations to show how vanadium(V) oxide acts as a catalyst in this process.

Equation 1

Equation 2

Table 6 shows some electrode half-equations and their standard electrode potentials.

Sn reduces VO₂⁺ in acidic solution.

Use the data in Table 6 to deduce an overall equation for the reaction that occurs.

Vanadium(III) sulfate is a pale yellow solid at room temperature.

Explain why vanadium(III) sulfate has a high melting point.

When vanadium(III) sulfate dissolves in water, the vanadium-containing species formed is acidic.

Give an equation to show how vanadium(III) sulfate dissolves in water to form the acidic vanadium-containing species.

Explain why the vanadium-containing species is acidic.

Equation

Compound Q is found in crude oil and has the molecular formula C₃₃H₃₄N₄VO₄

A sample of Q is ionised by electrospray ionisation in a time of flight (TOF) mass spectrometer. The spectrum produced shows that the

Give an equation to show how Q is ionised using electrospray ionisation.

Determine the m / z value of the molecular ion formed in this ionisation process.

Equation

A sample of vanadium contains only⁴⁹V and⁵¹V

The relative atomic mass of vanadium in this sample is 50.97

Calculate the percentage abundance of⁵¹V in this sample.

This question is about metals and their compounds.

State why the atomic radius of calcium is greater than the atomic radius of magnesium.

Magnesium reacts with steam.

Give an equation, including state symbols, for this reaction.

Similar-sized pieces of barium and magnesium are added to separate 100 cm³ samples of dilute sulfuric acid. In each case the sulfuric acid is in excess.

The barium reacts quickly at first. After a few minutes the reaction stops, even though there is still some unreacted barium in the flask.

The magnesium reacts more slowly than the barium, but the reaction continues until all the magnesium has reacted.

Explain why

• the barium initially reacts more quickly than the magnesium

• the barium reaction stops before all the barium has reacted.

A metal nitrate X(NO₃)₂ completely decomposes when heated.

A 0.832 g sample of X(NO₃)₂ decomposes on heating to produce a total of

Deduce the identity of metal X.

The ideal gas constant, R = 8.31 J K^–1 mol^–1

Identity of metal X

Sodium reacts with aluminium and hydrogen to form solid NaAlH₄

Give an equation for this reaction.

Suggest why NaAlH₄ has a high melting point.

Equation

Give the equation for the reaction between H₃PO₄ and an excess of NaOH

Lithium is an important metal used in cells to power mobile phones.

In a lithium cell, a lithium cobalt oxide electrode and a lithium electrode are used.

Give the equation for the reaction that occurs at the positive electrode.

Commercial electrochemical cells can be rechargeable or non-rechargeable.

State why lithium cells can be recharged.

Which substance has significant electron delocalisation?

What happens when water is vaporised?

This question is about Period 3 elements and their compounds.

Which is not a correct statement about magnesium hydroxide?

Tick (✓) one box.

Give an equation for the reaction of aluminium oxide with sulfuric acid.

Identify a reagent or test that could be used to distinguish between aqueous solutions of sulfur dioxide and sulfur trioxide with the same concentrations.

State the observation in each case.

Observation with sulfur dioxide solution

Observation with sulfur trioxide solution

The mass spectrum of the element phosphorus has a peak at = 124

Give the formula of the species responsible for this peak.

Give an equation for the reaction of phosphorus(V) oxide with sodium hydroxide solution.

Draw the displayed formula of the molecule formed when phosphorus(V) oxide reacts with water.

Table 4 shows the melting points of three substances.

Explain why the melting points of these substances are different.

You should refer to the structure of and bonding in each substance.

Which substance has no delocalised electrons?

In which substance do covalent bonds break when it melts?

Which substance contains delocalised electrons?

Which has a bond angle of 109.5°?

Which is not responsible for conduction of electricity?

This question is about sodium and some of its compounds.

Use your knowledge of structure and bonding to explain why sodium bromide has a melting point that is higher than that of sodium, and higher than that of sodium iodide.

When 250 mg of sodium were added to 500 cm³ of water at 25 °C a gas was produced.

Give an equation for the reaction that occurs. Calculate the volume, in cm³, of the gas formed at 101 kPa

The gas constant, R = 8.31 J K^–1 mol^–1

Calculate the concentration, in mol dm^–3, of sodium ions in the solution produced in the reaction in Question 08.2.

Sodium reacts with ammonia to form the compound NaNH₂ that contains the

Draw the shape of the NH₂^– ion. Include any lone pairs of electrons that influence the shape.

Predict the bond angle. Justify your prediction.

Shape