Preliminary Chemistry NSW Module 3 Questions PDF

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Preliminary Chemistry NSW Module 3 Questions...

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Preliminary Chemistry NSW Module 3 Questions CHEMICAL REACTIONS - Questions 1. Predict the products of the following reactions to complete and balance the equations: a HCl(aq) + KOH(aq) → b HCl(aq) + Ca(s) → c HNO3(aq) + CaCO3(s) → d Ca(s) + O2(g) → e C2H6(g) + O2(g) → 2. Write a balanced chemical equation and ionic equation for the reaction that takes place when solutions of the following compounds are mixed. In each case, name the spectator ions. Refer to the solubility mnemonic NAG SAG PMS CASTRO BEAR a copper(II) sulfate and sodium carbonate b silver nitrate and potassium chloride c sodium sul฀de and lead(II) nitrate d iron(III) chloride and sodium hydroxide e iron(III) sulfate and potassium hydroxide 3. Write balanced chemical equations and ionic equations for each of the following precipitation reactions: a NH4Cl(aq) + AgNO3(aq) → b FeCl2(aq) + Na2S(aq) → c Fe(NO3)3(aq) + KOH(aq) → d CuSO4(aq) + NaOH(aq) → e Ba(NO3)2(aq) + Na2SO4(aq) →

PREDICTING REACTIONS OF METALS - Questions

1. Use the information provided in the following table to rank metals I, II, III and IV in order of reactivity from most reactive to least reactive. Justify your ranking in terms of each of the three properties listed in the table. Property

Metal I

II

III

IV

atomic radius (pm)

122

200

140

160

first ionisation energy (kJ mol-1)

745

419

738

496

electronegativity

1.9

0.8

1.3

0.9

2. Consider the following information relating to three metals (‘R’, ‘S’ and ‘T’) and solutions of their salts (T(NO3)2, RNO3 and S(NO3)2). Three experiments were carried out with these metals to determine their order of reactivity. Equations representing what happened in these experiments are listed below. Experiment 1: T(s) + 2RNO3(aq) → T(NO3)2(aq) + 2R(s) Experiment 2: T(NO3)2(aq) + S(s) → no reaction Experiment 3: S(s) + RNO3(aq) → no reaction Determine the order of reactivity of the three metals, from most reactive to least reactive.

3. The following half-equations form part of the activity series of metals. The metals are ranked in order of decreasing reactivity, as shown: Mg(s) → Mg2+(aq) + 2eAl(s) → Al3+(aq) + 3 eZn(s) → Zn2+(aq) + 2 eFe(s) → Fe2+(aq) + 2 ePb(s) → Pb2+(aq) + 2 eAg(s) → Ag+(aq) +2 ea Which species loses its valence electrons most readily? b Which species gains electrons most readily?

c Lead rods are placed in solutions of silver nitrate, iron(II) sulfate and magnesium chloride. In which solutions would you expect to see a coating of another metal form on the lead rod? d Which of the metals silver, zinc or magnesium might be coated with lead when immersed in a solution of lead(II) nitrate? 4. Predict whether the following mixtures would result in reactions. Write an ionic equation for each reaction that you predict will occur. a Zinc metal is added to a solution of silver nitrate. b Copper metal is placed in an aluminium chloride solution. c Tin(II) sulfate is placed in a copper container. d Magnesium metal is added to a solution of lead(II) nitrate. e Silver metal is added to nickel(II) chloride solution. f Solutions of potassium chloride and copper(II) chloride are mixed. g Potassium nitrate solution is added to a silver container. h Lead metal is placed in a solution of silver nitrate.

If a piece of zinc metal is added to solutions of the following compounds, will a reaction be expected? If so, write a balanced chemical equation for the reaction. a AlCl3 b AgN3 c SnCl2 d CuSO4 5.

Redox reactions and galvanic cells - Questions 1. Lead metal is oxidised to form Pb2+ions by reaction with silver ions in solution. Write half-equations for the reaction and then write the balanced overall equation. 2. Complete the summary in the table as you balance the half-equation for the reduction of NO3− to NO2 in acidic solution. NO3−(aq) → NO2(g) Step 1

Task Balance nitrogens.

How its done

2

Balance oxygens by adding _______.

Add _____ H2O molecule(s) to the right-hand side of the equation

3

Balance hydrogens by Add ______ H+ ion(s) to the adding _________ side of the _____. equation.

4

Balance charge by adding _______.

Charge on left-hand side = ______ Charge on right-hand side = ______ Add ______ e− to the _______ side of the equation.

5

Add state symbols to give the final half-equation

Give the appropriate states for each reactant and product in the equation

Half-equation NO3−(aq) → NO2 (g)

3. What is the oxidation number of sulfur in each of the following compounds? a SO2 b H2S c H2SO4 d SO3 e Na2SO3 f Na2S2O3 4. Two half-cells are set up. One contains a solution of magnesium nitrate with a strip of magnesium as the electrode. The other contains lead(II) nitrate with a strip of lead as the electrode. The solutions in the two halfcells are connected by a piece of ฀lter paper soaked in potassium nitrate solution. When the electrodes are

connected by wires to a galvanometer, the magnesium electrode is shown to be negatively charged. a Sketch the galvanic cell described. Label the positive and negative electrodes. Mark the direction of the electron flow. b Write the half-equations for the reactions that occur in each half-cell and an equation for the overall reaction. c Label the anode and cathode. d Indicate the direction in which ions in the salt bridge migrate

Rates of Reactions - Questions

This graph is an energy profile diagram for the reaction between chloromethane and hydroxide ion. Energy profile diagram for the reaction between CH3Cl and OH-

1. a Copy this diagram and label ∆H and activation energy Ea. b Explain what is meant by the term ‘activation energy’. c Label the transition state of this reaction on your diagram. d What bonds are beginning to be broken and formed to produce the transition state?

Lumps of limestone (calcium carbonate) react readily with dilute hydrochloric acid. Four large lumps of limestone (total mass 10.0 g) were reacted with 100 mL 0.100 mol L-1 a Write a balanced equation to describe the reaction. b Which reactant is in excess? Use a calculation to support your answer. c Describe a technique that you could use in a school laboratory to measure the rate of the reaction. d 10.0 g of small lumps of limestone will react at a different rate from four large lumps. Will the rate of reaction with the smaller lumps be faster or slower? 2.

Explain your answer in terms of collision theory. e List two other ways in which the rate of this reaction can be altered. Explain your answer in terms of collision theory...