Group 2: the alkaline earth metals

This question is about some Group 2 elements and their compounds.

Magnesium is reacted with titanium(IV) chloride to extract titanium metal.

Give the equation for this reaction.

State the role of magnesium in this reaction.

Equation

Role of magnesium

Complete Table 1 by giving the formula of a suitable calcium compound for each use.

Magnesium hydroxide is used to relieve the symptoms of indigestion by neutralising stomach acid.

Suggest why magnesium hydroxide is safer than sodium hydroxide as a treatment for indigestion.

An ionic compound of a Group 2 element dissolves in water to form solution X.

Separate samples of solution X are tested to identify the ions.

Table 2 shows the observations.

Identify the Group 2 cation in solution X.

Give an ionic equation for the reaction that occurs in Test 1.

Ionic equation

Identify the anion in solution X.

Give an ionic equation, including state symbols, for the reaction that occurs in Test 2

Explain why AgNO₃(aq) is acidified.

Ionic equation

Give one property of barium sulfate that makes it useful in hospitals.

A piece of strontium is added to an excess of water.

Which observation is correct and complete?

Which property of the Group 2 elements increases with increasing atomic number?

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.

A student is given two aqueous solutions, L and M, that both contain iron salts.

The student does a series of tests on the solutions.

Table 1 shows these tests and the observations.

Identify L and M using the results in Table 1.

In your answer:

• identify all precipitates

• explain why effervescence is seen in the reaction of sodium carbonate with L but not with M

• give ionic equations for all reactions.

Barium metal is added to a large excess of water.

Which observation is correct and complete?

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.

This question is about some elements in Group 7 and their compounds.

Chlorine is added to some drinking water supplies to decrease the risk of people suffering from diseases such as cholera.

State why the amount of chlorine added must be controlled.

Give an equation for the reaction of chlorine with water to form a solution containing two acids.

Explain, with reference to electrons, why this is a redox reaction.

Equation

A student bubbles chlorine gas through a solution of sodium iodide.

State the observation the student would make.

Give an ionic equation for the reaction.

Ionic equation

The student adds a few drops of concentrated sulfuric acid to a small amount of solid sodium iodide.

Two gaseous sulfur-containing products are formed.

Give an equation for the formation of each of these sulfur-containing products.

State the role of sulfuric acid in the formation of these products.

Equation 1

Equation 2

The student adds a few drops of acidified silver nitrate solution to a solution of an unknown impure sodium halide. The student observes bubbles of gas and a colourless solution. The student bubbles the gas through calcium hydroxide solution and a white precipitate forms.

Deduce the identity of the sodium halide.

Suggest the identity of the gas.

Give an ionic equation for the formation of this gas from the impurity.

Identity of sodium halide

Ionic equation

The ClF₂⁺ ion contains two different Group 7 elements.

Use your understanding of the electron pair repulsion theory to draw the shape of this ion.

Include any lone pairs of electrons that influence the shape.

Explain why the ion has the shape you have drawn.

Suggest a value for the bond angle in the ion.

Shape

Magnesium is used in the extraction of titanium from titanium(IV) chloride.

Give an equation for this reaction.

Tschermigite is a hydrated, water-soluble mineral, with relative formula mass of 453.2

The formula of tschermigite can be represented as M.xH₂O, where M represents all the ions present.

Table 4 shows its composition by mass.

In an analysis, it is found that the mineral contains the ions NH₄⁺, Al³⁺ and SO₄²

Calculate the empirical formula of tschermigite and the value of x in M.xH₂O

Describe the tests, with their results, including ionic equations, that would confirm the identities of the ions present.

This question is about elements in Period 3 and their compounds.

When a piece of sodium is added to 200 cm³ of water in a large beaker a vigorous reaction occurs. The temperature of the water increases by 25^oC

Give an equation, including state symbols, for the reaction of sodium with water.

Suggest why it is dangerous to react a similar piece of sodium with 10 cm³ of water in a boiling tube.

Equation

Why it is dangerous

Give an equation for the reaction of phosphorus(V) oxide with water.

Suggest a pH for the solution formed.

Equation

Explain, in terms of crystal structure and bonding, why silicon(IV) oxide has a higher melting point than phosphorus(V) oxide.

An element in Period 3 forms an oxide that is insoluble in water. This oxide reacts with sulfuric acid and with aqueous potassium hydroxide.

Give the formula for this oxide.

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

Equation

Give the formula of a hydroxide of an element in Period 3 used in medicine.

Identify the element in Period 3, from sodium to chlorine, that has the largest atomic radius.

What is the correct observation when barium metal is added to an excess of water?

An aqueous solution of a salt gives a white precipitate when mixed with aqueous silver nitrate and when mixed with dilute sulfuric acid.

Which could be the formula of the salt?

This question is about s-block metals.

Give the full electron configuration for the calcium ion, Ca²⁺

Explain why the second ionisation energy of calcium is lower than the second ionisation energy of potassium.

Identify the s-block metal that has the highest first ionisation energy.

Give the formula of the hydroxide of the element in Group 2, from Mg to Ba, that is least soluble in water.

A student added 6 cm³ of 0.25 mol dm^–3 barium chloride solution to 8 cm³ of 0.15 mol dm^–3 sodium sulfate solution. The student filtered off the precipitate and collected the filtrate.

Give an ionic equation for the formation of the precipitate. Show by calculation which reagent is in excess. Calculate the total volume of the other reagent which should be used by the student so that the filtrate contains only one solute.

Total volume of other reagent

A sample of strontium has a relative atomic mass of 87.7 and consists of three

State why the isotopes of strontium have identical chemical properties. Calculate the percentage abundance of the⁸⁸Sr isotope in this sample.

Why isotopes of strontium have identical chemical properties

A time of flight (TOF) mass spectrum was obtained for a sample of barium that

Identify the ion with the longest time of flight.

A¹³⁷Ba⁺ ion travels through the flight tube of a TOF mass spectrometer with a

The Avogadro constant, L = 6.022 × 10²³ mol^–1

Calculate the length of the flight tube in metres. Give your answer to the appropriate number of significant figures.

Which products are formed when magnesium reacts with steam?

Some 1.0 mol dm^–3 solutions were mixed using equal volumes of each solution.

Which pair of solutions would give the greatest mass of solid?