QUESTIONSHEETS GROUPS 1 AND 2 REACTIONS OF THE ELEMENTS WITH WATER REACTIONS OF THE ELEMENTS WITH DILUTE ACIDS

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1 CHEMISTRY QUESTIONSHEETS AS Level AS TOPIC 10 GROUPS 1 AND 2 Questionsheet 1 Questionsheet 2 Questionsheet 3 Questionsheet 4 Questionsheet 5 Questionsheet 6 Questionsheet 7 Questionsheet 8 Questionsheet 9 Questionsheet 10 Questionsheet 11 Questionsheet 12 Questionsheet 13 Questionsheet 14 ELECTRONIC CONFIGURATIONS AND PHYSICAL PROPERTIES IONISATION ENERGIES REACTIONS OF THE ELEMENTS WITH OXYGEN AND CHLORINE REACTIONS OF THE ELEMENTS WITH WATER REACTIONS OF THE ELEMENTS WITH DILUTE ACIDS GROUP 2 OXIDES WITH WATER AND DILUTE ACIDS HYDROXIDES OF GROUPS 1 AND 2 CHLORIDES SULPHATES OF GROUP 2 CARBONATES NITRATES FLAME TEST USES OF GROUP 2 COMPOUNDS TEST QUESTION 15 marks 17 marks 16 marks 17 marks 13 marks 16 marks 16 marks 15 marks 16 marks 17 marks 17 marks 22 marks 15 marks 11 marks Authors Trevor Birt Donald E Caddy Andrew Jones Adrian Bond Editors John Brockington Stuart Barker John Brockington Kevin Frobisher Andy Shepherd Stuart Barker Curriculum Press Licence Agreement: Paper copies of the A-Level Chemistry Questionsheets may be copied free of charge by teaching staff or students for use within their school, provided the Photocopy Masters have been purchased by their school. No part of these Questionsheets may be reproduced or transmitted, in any other form or by any other means, without the prior permission of the publisher. All rights are reserved. This license agreement is covered by the laws of England and Wales Curriculum Press March Curriculum P ress Curriculum Press Bank House 105 King Street Wellington Shropshire TF1 1NU

2 TOPIC 10 Questionsheet 1 ELECTRONIC CONFIGURATIONS AND PHYSICAL PROPERTIES a) Define the term s-block element. b) (i) What oxidation numbers(s) do the elements of Group 2 display in their compounds? What principal feature do the electronic configurations of these elements have in common? c) Give the electronic configurations of a strontium atom and of a calcium cation. Sr... [1] Ca [1] d) The following table gives some physical properties of six s-block elements. Metal Melting temperature / K Density / g cm -3 Group 1 Lithium Sodium Potassium Group 2 Calcium Strontium Barium State and explain how the melting temperatures and densities of the s-block elements vary on progressing down Groups 1 and 2 of the Periodic Table. Melting temperatures... Densities... e) Are the atomic radii of s-block elements smaller or larger than the ionic radii of their cations? How do you account for this? TOTAL / 15

3 TOPIC 10 Questionsheet 2 IONISATION ENERGIES a) Would you expect the first ionisation energy of magnesium to be higher or lower than that of sodium? Explain your answer. b) (i) Define the term second ionisation energy and write an equation to show this change. Briefly explain how and why the first and second ionisation energies of the Group 2 elements vary down the group. (iii) Explain why the second ionisation energy of sodium is much greater than that for magnesium c) Use ionisation energies to explain why Group 2 metals are not used as reducing agents in some industrial processes as are some Group 1 metals. TOTAL / 17

4 TOPIC 10 Questionsheet 3 REACTIONS OF THE ELEMENTS WITH OXYGEN AND CHLORINE a) Write chemical equations for the combination of magnesium and: (i) chlorine... [1] oxygen... [1] b) Which of the reactions in a) would occur most readily? Give brief reasoning Reaction... [1] Reasoning... [1] c) Write down the oxidation number of oxygen in Group 2 oxides. Oxidation number... [1] d) Anhydrous calcium chloride can be prepared by passing dry chlorine over heated calcium. (i) When carrying out this reaction in the laboratory, suggest one important safety precaution. Why does the chlorine have to be dry? (iii) Give the type of bonding in calcium chloride (iv) Give a use for calcium chloride in the laboratory e) Suggest, giving your reasoning, which of the following oxides: magnesium oxide, strontium oxide, barium oxide or calcium oxide has the highest melting point: f) A Group 2 bromide contains 20% by mass of the metallic element M. Calculate the relative atomic mass of M. TOTAL / 16

5 TOPIC 10 Questionsheet 4 REACTIONS OF THE ELEMENTS WITH WATER a) Under what conditions does water react rapidly with magnesium? State what you would observe and write a balanced chemical equation for the reaction, giving the states of matter for all reactants and products. Conditions... [2] Observations... [2] Equation... [2] b) State the conditions and write a similar chemical equation for the reaction of barium powder with water. Conditions... [1] Equation... [2] c) State and explain two ways in which the reactions in a) and b) differ from each other. Difference 1... [1] Explanation... [1] Difference 2... [1] Explanation... [1] d) (i) In its reaction with water, is sodium more reactive than magnesium or less reactive? Explain your answer to d) (i) in terms of atomic structure. TOTAL / 17

6 TOPIC 10 Questionsheet 5 REACTIONS OF THE ELEMENTS WITH DILUTE ACIDS a) Magnesium sulfate can be prepared by dissolving magnesium in dilute sulfuric acid and then crystallising the solution. (i) Write two ionic half-equations for this reaction. Combine the half-equations into an overall ionic equation. (iii) Expand this ionic equation into a full chemical equation with state symbols. b) (i) Explain why it would not be economic, in the chemical industry, to manufacture magnesium sulfate by the method in b). Given that magnesium occurs naturally as magnesium carbonate ( magnesite ), suggest, with an equation, a cheaper method which could be used to manufacture crystals of magnesium sulfate. Method [2] Equation... [1] c) It is not chemically possible to prepare barium sulfate by dissolving barium in dilute sulfuric acid. Why is this? d) Ignoring economic aspects, explain why it would not be sensible to prepare sodium sulfate by dissolving sodium in dilute sulfuric acid. TOTAL / 13

7 TOPIC 10 Questionsheet 6 GROUP 2 OXIDES WITH WATER AND DILUTE ACIDS a) In a series of laboratory experiments, the oxides of Mg, Ca, Sr and Ba were shaken in a test tube with deionised water. Afterwards, the contents of each test tube were tested with a ph meter and it was found that, on progressing from magnesium oxide to barium oxide, the ph increased from ~7 to ~14. (i) Why should the ph, in any of these experiments, be greater than 7? Write an ionic equation for any reaction that occurs. (iii) Explain the increase in ph on progressing from magnesium oxide to barium oxide. (iv) State, with your reason, what type of chemical reaction occurs in these experiments. Type of reaction... [1] Reason [2] b) Calcium chloride can be prepared by dissolving either calcium or calcium oxide in hydrochloric acid, yet these two reactions are of different types. Write the ionic equation for each reaction, then classify it, and finally justify your classification by discussing the transfer of protons or electrons as appropriate. Calcium and hydrochloric acid Ionic equation... [1] Classification... [1] Justification... Calcium oxide and hydrochloric acid Ionic equation... [1] Classification... [1] Justification... TOTAL / 16

8 TOPIC 10 Questionsheet 7 HYDROXIDES OF GROUP 1 AND 2 a) Give an ionic equation for the reaction between calcium hydroxide and nitric acid b) Write balanced chemical equations, with state symbols, for 2 mol of calcium hydroxide reacting with each of the following in aqueous solution. (i) 1 mol of sulfuric acid 2 mol of sulfuric acid (iii) 1 mol of ammonium sulfate (iv) 1 mol of magnesium nitrate c) (i) Write an equation for the action of heat on magnesium hydroxide. On descending Group 2 of the Periodic Table, does the decomposition of hydroxides require lower temperatures or higher temperatures? d) What trend in the solubility of hydroxides in water is observed on descending Group 2? How would the ph of a saturated solution of the hydroxide change down the group? Trend... [1] ph... [1] e) Calcium hydroxide is sometimes used in crop production. (i) Suggest the use in question Powdered limestone is also used for this purpose as calcium hydroxide. Suggest two disadvantages of calcium hydroxide by comparison. Disadvantage 1... [1] Disadvantage 2... [1] TOTAL / 16

9 TOPIC 10 Questionsheet 8 CHLORIDES a) (i) Explain the term polarising power of a cation. Describe how the polarising powers of M 2+ cations of Group 2 vary. Polarising power... [1] Variation... [1] Explanation... [1] From your answer to (i), suggest which anhydrous Group 2 chloride is covalent and state the geometry of this molecule Chloride... [1] Geometry... [1] (iii) The polarising power of the cations of lithium and magnesium are similar, despite the ions having different charges. How do you account for this? b) Explain why an aqueous solution of magnesium chloride of a given molarity has a ph of 5.5 and an aqueous solution of sodium chloride of the same molarity has a ph of 7.0. Quality of language [1] c) When recrystallised from water, the chlorides of lithium and of the Group 2 elements contain water of crystallisation. The chlorides of the other Group 1 elements do not have water of crystallisation when prepared in this way. Suggest why this occurs. TOTAL / 14

10 TOPIC 10 Questionsheet 9 SULFATES OF GROUP 2 The solubility of a salt has a major bearing on its method of preparation. Illustrate the truth of this statement by outlining the preparation of: a) magnesium sulfate (a soluble salt) from magnesium oxide, b) barium sulfate (an insoluble salt) from barium oxide. In your answers you should name any reagents which are required, state (but do not describe) the necessary laboratory techniques, and write chemical equations for the reactions involved. a) Magnesium sulfate Reagent(s) and techniques Equation(s)... [8] b) Barium sulfate Reagent(s) and techniques Equation(s)... [7] c) What does this suggest about the change in enthalpy of solution for the sulfates on descending Group 2? TOTAL / 16

11 TOPIC 10 Questionsheet 10 CARBONATES a) How do the solubilities of the carbonates of Group 2 elements compare with those of Group 1 elements? Explain why there is a variation. Comparison... [1] Explanation... b) Write balanced chemical equations, including state symbols, for the reactions which occur on heating the following compounds with a Bunsen burner. Lithium carbonate... [1] Sodium carbonate... [1] Magnesium carbonate... [1] c) How would you test for the presence of one of the products of the thermal decomposition of magnesium carbonate? d) Magnesium carbonate undergoes thermal decomposition rapidly at around 700 o C. Would the thermal decomposition of barium carbonate require a higher or lower temperature? Explain your choice. e) (i) Describe, with the aid of a chemical equation, what would occur if carbon dioxide were bubbled through an aqueous solution of radium hydroxide. Suggest what you would observe if dilute hydrochloric acid were added to the reaction mixture obtained from e) (i). Explain your predictions using a chemical equation. TOTAL / 17

12 TOPIC 10 Questionsheet 11 NITRATES a) The following compounds decompose when they are heated with a Bunsen burner. Write chemical equations for each decomposition and state how you could identify any gases evolved. (i) Lithium nitrate Equation... [1] Sodium nitrate Equation... [1] (iii) Calcium nitrate Equation... [1] Identification of gases [3] b) On heating, g of a compound X, known to be either sodium nitrate or potassium nitrate, evolved 30.0 cm 3 of gas at room temperature and pressure. Identify X and show your working clearly. (Assume that 1 mole of any gas occupies 24.0 dm 3 at room temperature and pressure.) c) State and explain the trend in thermal stability of nitrates: (i) within Group 2. from magnesium to sodium. TOTAL / 17

13 TOPIC 10 Questionsheet 12 FLAME TEST a) Outline the experimental procedure for carrying out the flame test on solid samples of pure compounds. Give a list of apparatus and reagents needed for this test. Apparatus... [2] Reagent(s)... [1] Procedure... b) Explain how an ion M + causes a flame colour. c) Identify the salts A, B, C, D and E from the following information, and in each case write an equation for the chemical reaction described. (i) A gives a golden yellow flame, and on heating evolves a colourless gas which relights a glowing splint. Identity of A... [1] Equation... [2] B gives an apple green flame, and in aqueous solution gives a white precipitate with aqueous silver nitrate. Identity of B... [1] Equation... [2] (iii) C gives a brick red flame, and on heating gives off a colourless gas which turns limewater milky. Identity of C... [1] Equation... [1] (iv) D gives a lilac flame, and in aqueous solution gives a white precipitate with aqueous barium chloride. Identity of D... [1] Equation... [2] (v) E gives a crimson flame, and on heating evolves brown fumes. Identity of E... [1] Equation... [2] TOTAL / 22

14 TOPIC 10 Questionsheet 13 USES OF GROUP 2 COMPOUNDS a) Complete the following table by inserting one major use, in industry, agriculture or medicine, of the compounds shown. Compound Use Calcium hydroxide Magnesium hydroxide Calcium carbonate Magnesium oxide Barium sulfate [5] b) (i) Describe how you would carry out the limewater test for carbon dioxide, assuming that you were working on a small scale with test tubes and a teat pipette but no other apparatus. Explain why, in the limewater test, the milkiness disappears in the presence of excess carbon dioxide. c) Barium chloride solution is useful in qualitative analysis. (i) What anion is it used to detect? What observation can be expected if that anion is present? (iii) Write an ionic equation for the reaction. (iv) Why should an aqueous solution be acidified with HCl(aq) before BaCl 2 (aq) is added to it in this test? TOTAL / 15

15 TOPIC 10 Questionsheet 14 TEST QUESTION CO 2 C a) The mineral witherite (BaCO 3 ) is a white solid which resembles marble (CaCO 3 ) in its properties. When a lump of witherite is heated it turns into a white powder, substance A, which swells up and gives off steam when water is added. The product obtained by treating substance A with water is substance B, which dissolves slightly in water to give an alkaline solution. A saturated aqueous solution of substance B produces a white precipitate, substance C, when carbon dioxide is bubbled through it. (i) Give chemical names for substances A, B and C. A =... [1] B =... [1] C =... [1] Write chemical equations for all the chemical reactions occurring in the above account. A =... [1] B =... [1] C =... [1] b) Excess magnesium carbonate powder was added to dilute sulfuric acid and the mixture was stirred until the effervescence finished. The suspension was then filtered, leaving a white powder in the filter paper and a colourless solution. The filtrate was left to allow the water to evaporate off, and a white crystalline solid was produced. (i) Write an equation for the chemical reaction. What caused the effervescence?... [1] (iii) What was the solid left in the filter paper?... [1] (iv) What was the name of the substance which appeared as a white crystalline solid? (v) What observations would have been different if magnesium oxide had been used in the place of magnesium carbonate? TOTAL / 11

QUESTIONSHEETS PERIODIC TABLE I MELTING POINTS AND BOILING POINTS IONISATION ENERGIES AND ELECTRON AFFINITIES ELECTRONEGATIVITIES AND BONDING

QUESTIONSHEETS PERIODIC TABLE I MELTING POINTS AND BOILING POINTS IONISATION ENERGIES AND ELECTRON AFFINITIES ELECTRONEGATIVITIES AND BONDING CHEMISTRY QUESTIONSHEETS AS Level AS TOPIC 9 PERIODIC TABLE I Questionsheet 1 Questionsheet 2 Questionsheet 3 Questionsheet 4 Questionsheet 5 Questionsheet 6 Questionsheet 7 Questionsheet 8 Questionsheet