Questions and Answers of Cambridge International AS And A Level Chemistry

a. What would happen if octane was added to a solution of sodium hydroxide?b. Explain your answer to part a.
a. Draw the displayed formula and the skeletal formula of cyclopentane.b. What is the general formula of cycloalkanes?c. Give two differences between a molecule of cyclopentane and a molecule of
a. Alkanes are saturated hydrocarbons. Explain the words saturated and hydrocarbons.b. Alkanes are generally unreactive. Explain why this is so.c. Write balanced symbol equations for the complete
2-Methylpentane, 3-ethylpentane and 2,3-dimethylbutane are alkanes.a. For each one give:i. Its molecular formulaii. Its structural formulaiii. Its displayed formulaiv. Its skeletal formula.b. Give
Eicosane is a straight-chain alkane whose molecules contain 20 carbon atoms.a. What is the molecular formula of eicosane?b. Draw the skeletal formula of eicosane.
Classify these reactions, choosing from the types of reaction described above:a. C3H7I + H2O → C3H7OH + HIb. CH3CHO + 2[H] → CH3CH2OHc. C2H5Br → C2H4 + HBrd. C2H4 + H2O → C2H5OHe. C2H6 + Cl2
a. Write an equation to show the homolytic fission of the Cl — Cl bond in a chlorine molecule, Cl2.b. Write an equation to show the heterolytic fission of the C — Cl bond in chloromethane.
a. Draw the displayed formulae and name the cis–trans isomers of but-2-ene.b. The molecule CHBrClF exhibits optical isomerism. Draw the 3D displayed formulae of both optical isomers.
Draw the displayed formulae and give the names of the isomers of C5H12.
a. Draw the displayed formulae and name the functional group isomers of C3H6O that are:i. An aldehydeii. A ketone.b. Draw the displayed formula and name an isomer of C3H8O that could be used as an
a. Name the four isomers in Figure 14.15.b. Draw the displayed formulae and name the structural isomers of C3H7Cl. Br Br H Br H Br Н—с —с —С—Н H-C-C-C-H H H H H H H Br H H Br H-C-c-c-H
Draw a 3D formula for:a. Propaneb. Propene.
a. Draw the skeletal formula of pentane, a straight chain hydrocarbon with a molecular formula of C5H12.b. Draw the structural formulae of the molecules shown in Figure 14.2, parts d, e and f.
A chemist was investigating the best way to produce 1,2-dichloroethane. He devised two methods, I and II, of doing this.I. He reacted ethane with chlorine in the presence of UV light by the following
Draw the displayed formula of:a. Ethene (molecular formula C2H4)b. Propane (molecular formula C3H8).
A carbon compound P has the percentage composition 85.7% carbon and 14.3% hydrogen. Its relative molecular mass was found to be 56.a. i. Calculate its empirical formula.ii. Calculate its molecular
a. i. On analysis a hydrocarbon was found to contain 0.72 g of carbon and 0.18 g of hydrogen. What is the empirical formula of the hydrocarbon?ii. Further investigation showed that the relative
a. Write a balanced equation, including state symbols, showing the formation of sulfuric acid from atmospheric sulfur trioxide, SO3.b. List three consequences of acid rain.
a. Why is ammonia so important in providing enough food to feed the world?b. Give one environmental problem and one possible health problem associated with nitrate fertilisers.c. Explain how nitrogen
The reaction 2SO2(g) + O2(g) ⇌ 2SO3(g) reaches dynamic equilibrium. The forward reaction is exothermic. The reaction is catalysed by vanadium(V) oxide, V2O5. You are given a vessel containing all
a. Ammonia is made in industry using the Haber process. Write the balanced equation to show the synthesis of ammonia from its elements, including the catalyst used.b. Write a balanced equation,
Ammonia is made in the Haber process.a. What is the formula of ammonia?b. Write a balanced equation for the formation of ammonia from nitrogen and hydrogen in the Haber process.c. Give three uses of
a. Explain the lack of reactivity of nitrogen gas.b. Write a balanced chemical equation, including state symbols, for the reaction of ammonia solution with dilute nitric acid.c. Write a balanced
a. What type of reaction takes place between chlorine and hot aqueous sodium hydroxide?b. Write an ionic equation for the reaction of chlorine with hot aqueous sodium hydroxide.c. Write a
a. For the reaction of chlorine with water:i. Write a balanced chemical equationii. Give the oxidation numbers of chlorine before and after the reactioniii. Give one use for the process.b. For the
a. You suspect that a solid compound might be potassium bromide. Describe how you would test your idea and the positive results you would get if you were correct.b. i. What would you see in a test
a. Complete the equations below, including state symbols.i. AgNO3(aq) + NaCl(aq) → …ii. AgNO3(aq) + NaBr(aq) → …iii. AgNO3(aq) + NaI(aq) → …b. What would you observe in each reaction in
a. Astatine (At) lies below iodine at the bottom of Group 17. Predict:i. The equation for its reaction with hydrogenii. The vigour of its reaction with hydrogeniii. The thermal stability of its
a. Describe the acid–base nature of the solutions obtained when the following compounds are added to water. Use equations to illustrate your answers.i. Sodium chlorideii. Sulfur trioxideiii. Sodium
a. Which of these mixtures will result in a chemical reaction?i. Bromine solution and sodium chloride solutionii. Iodine solution and sodium bromide solutioniii. Chlorine solution and potassium
Chlorine water is mixed with a solution of potassium iodide in a test tube. 2 cm3 of cyclohexane is added to the test tube, which is stoppered and shaken, then allowed to stand.a. Write a balanced
a. What is the molecular formula of bromine?b. Put the elements bromine, chlorine and iodine in order of boiling point, starting with the lowest.c. Explain the reasons for the trend described in part
a What trend in volatility is seen going down Group 17?b. Using Table 12.1, what is the state of each halogen at 20°C?c. What is the trend in the atomic radii of the halogens? Explain this trend.d.
a. How is limestone turned into lime in industry?b. Which major construction materials are made from cement?c. Both calcium carbonate and magnesium oxide have giant ionic structures. Why is magnesium
For the following reactions, state which element is oxidised and which one is reduced, and give the changes in oxidation number.a. Sr + Cl2 → SrCl2b. Sr + 2H2O → Sr(OH)2 + H2c. 2Mg + CO2
a. Write a balanced symbol equation for the reaction of barium carbonate with dilute nitric acid.b. Which one of the three compounds listed will decompose at the lowest temperature?i. Calcium
a. Limewater is calcium hydroxide.i. Give the formula of calcium hydroxide.ii. Explain why calcium hydroxide is used in agriculture.b. Exactly 0.1 moles of calcium hydroxide and barium hydroxide are
a. Write a balanced chemical equation, including state symbols, for the reaction of:i. Strontium with oxygenii. Strontium oxide with water.b. i. Write a balanced chemical equation, including state
Beryllium and radium are both in Group 2.a. Write the electronic configuration of beryllium.b. Give the equations for the reactions of beryllium and radium with oxygen.c. Using dot-and-cross
a. Look at Figure 11.3.i. What is the general trend in the melting points going down Group 2?ii. Which element breaks the trend?b. Explain why the atoms in Group 2, as in any other group, get larger
a. The chloride of an unknown element, X, is a liquid at 20°C. This chloride reacts with water, giving white fumes and leaving an acidic solution.i. Does element X belong to Group 1, Group 2 or
a The element germanium is in Group 14, in Period 4. It is classed as a semimetal or metalloid, as is silicon in Period 3.i. Predict the chemical bonding and structure of the element germanium.ii.
a. i. The Group 1 metal lithium reacts in a similar way to sodium. It reacts with oxygen, producing lithium oxide. Write the balanced symbol equation, including state symbols, for this reaction.ii.
a. What is the general trend in first ionisation energies across Period 3?b. Explain why aluminium has a lower first ionisation energy than magnesium.c. Explain why sulfur has a lower first
a i Describe how the atomic radius varies across Periods 2 and 3.ii. Explain this trend.b. i. Describe how the atomic radius varies down each group of the Periodic Table.ii. Explain this trend.
a. Why does sulfur have a lower melting point than silicon?b. Why does sulfur have a higher melting point than chlorine?c. Why is magnesium a better electrical conductor than:i. Phosphorus?ii. Sodium?
The variation of melting point with atomic number for Periods 2 and 3 is shown in the graph below.a. Explain what we mean when we say melting point is a periodic property.b. Explain the following.i.
Look at the elements in Period 2 of the Periodic TABLE. Using your knowledge of Period 3 elements, predict and explain the relative sizes of:a. The atomic radii of lithium and fluorine.b. A lithium
a. Explain what is meant by the term ‘periodic property’.b. The graph shows how a periodic property varies when plotted against atomic number for Period 3 (sodium to argon).i. Identify the
Look at the Periodic Table in Figure 10.2.Figure 10.2a. Which element is found in Period 4, Group 17?b. The relative atomic masses of tellurium (Te) and iodine (I) are 128 and 127, respectively. Why
The activation energy for the uncatalysed decomposition of ammonia to its elements is +335 kJ mol−1.a. Write the equation for this reaction, including state symbols.b. The enthalpy of reaction for
a i. Explain whether the reaction below is an example of heterogeneous or homogeneous catalysis:ii. Explain how a catalyst increases the rate of reaction in terms of activation energy and the
The Haber process is used in industry to convert nitrogen and hydrogen to ammonia. The formation of ammonia gas is exothermic.a. Sketch the enthalpy profile for the Haber process in the absence of a
a. What is the Boltzmann distribution?b. Explain why a 10°C rise in temperature can approximately double the rate of a reaction.
a. Sketch a graph to show the Boltzmann distribution of molecular energies. Label the axes.b. What is meant by activation energy?c. Shade an area on the graph to show the number of molecules capable
a. Dilute hydrochloric acid reacts with marble chips (calcium carbonate), giving off carbon dioxide gas. Which solution of acid will have the fastest initial rate of reaction:A. 50 cm3 of 0.5mol
a. Explain why gases react together faster at higher pressure.b. Explain why reactants in solution react faster at higher concentration.c. Explain why finely divided solids react more quickly than
a. Draw a different set of apparatus that could be used to monitor the reaction shown in Figure 9.2.b. What do we mean by:i. The activation energy of a reaction?ii. A catalyst?c. Does a catalyst work
Iodine, I2, reacts with thiosulfate ions, S2O32–to form iodide ions, I–, and tetrathionate ions, S4O62–I2+S2O32–→2I– + S4O62–a. State the oxidation number of each sulfur atom in:i.
Give the full systematic names of the following:a. Na2SO3b. Na2SO4c. Fe(NO3)2d. Fe(NO3)3e. Feso4f. Cu2Og. H2SO3h. Mn2O7
State the ox. no. of the bold atoms in these compounds or ions: a. P2O5b. SO42-c. H2Sd. AL2CL6e. NH3f. ClO2-g. CaCO3
a. Deduce the change in ox. no. for the bold atoms or ions in each of the following equations. In each case, state whether oxidation or reduction has taken place.i. 2I– + Br2 → I2 +
Use the information in Figure 6.15 and the information below to show that the average bond energy of the C — H bond is 415.9 kJ mol–1ΔHϴf[CH4] = –74.8 kJ mol–1ΔHϴat [ 1⁄2 H2] = +218 kJ
a. Draw an enthalpy cycle to calculate the enthalpy change of formation of ethanol, C2H5OH, using enthalpy changes of combustion.b. Calculate a value for ΔHϴf [C2H5OH(l)] using the
a. Draw an enthalpy cycle to calculate ΔHϴr for the reaction 2Al(s) + Fe2O3(s) → 2Fe(s) + Al2O3(s)b. Calculate ΔHϴr using the following information:ΔHϴf [Fe2O3(s)] = –824.2
a. Define standard enthalpy change of reaction.b. Given the enthalpy changes ΔH1 and ΔH2 below, construct a Hess’s cycle that will enable you to find the enthalpy change, ΔHr, for the
A student calculated the standard enthalpy change of combustion of ethanol ΔHϴc [C2H5OH] by calorimetry as –870 kJ mol–1. The data book value is –1367 kJ mol–1. Explain the difference
A student added 10 g (0.25 mol) of sodium hydroxide to 40 cm3 of water to make a concentrated solution. All the sodium hydroxide dissolved. He measured the maximum temperature rise. He suggested that
a. Define average bond enthalpy.b. Use the average bond enthalpies that follow to calculate a value for the enthalpy change for the reaction:H2 + I2 → 2HIE(H — H) = +436 kJ mol–1E(I — I) =
Explain why the enthalpy change of neutralisation of one mole of sulfuric acid, H2SO4, is not the standard enthalpy change of neutralisation.
a. Define standard enthalpy change of formation.b. Calculate the standard enthalpy change of formation of methane from the following standard enthalpy changes of combustion:carbon = –394 kJ
a. Calculate the energy transferred when the temperature of 75 cm3 of water rises from 23 °C to 54 °C.b. When 8 g of sodium chloride is dissolved in 40 cm3 of water the temperature falls from 22
a. Define standard enthalpy change of combustion.b. When red phosphorus burns in oxygen the enthalpy change is –2967 kJ mol–1. For white phosphorus the enthalpy change is –2984 kJ mol–1. For
Classify each of the following reactions as ΔHϴr, ΔHϴf or ΔHϴc :a. MgCO3(s) → MgO(s) + CO2(g)b. C(graphite) + O2(g) → CO2(g)c. HCl(g) + NH3(g) → NH4Cl(s)d. H2(g) +
240 cm3 of ethane (C2H6) was burnt in a controlled way and found to raise the temperature of 100 cm3 of water by 33.5 °C. (specific heat capacity of water = 4.18Jg–1K–1; 1mol of gas molecules
Draw enthalpy profile diagrams for: a. The combustion of sulfur to form sulfur dioxideb. The endothermic reactionH2O(g) + C(s) → H2(g) + CO(g)
Propanone is a liquid. It has the structureThe equation for the complete combustion of propanone is:CH3COCH3(l) + 4O2(g) → 3CO2(g) + 3H2O(l)a. Use the following bond energies (in kJ mol–1) to
Classify each process as exothermic or endothermic:a. The burning of magnesium in air.b. The crystallisation of copper(II) sulfate from a saturated solution.c. THe thermal decomposition of magnesium
Nitric acid is a strong acid but chloric(I) acid, HClO, is a weak acid.a. Explain the difference between a strong and a weak acid.b. Write equations showing the ionisation of each of these acids in
a. Identify the acid and the base on the right-hand side of these equilibria.i. HClO2 + HCOOH ⇋ ClO2– + HCOOH2+ii. H2S + H2O ⇋ HS– + H3O+b. Identify the acid on the right-hand side of
Identify which reactants are acids and which are bases in the following reactions:a. NH4+ + H2O ⇋ NH3 + H3O+b. HCOOH + HClO2 ⇋ HCOOH2 + + ClO2–
a. Write an equation to show potassium hydroxide dissolving in water.b. Write an equation for liquid nitric acid dissolving in water.c. Write ionic equations for:i. The reaction in aqueous solution
The Haber process for the synthesis of ammonia may operate at a temperature of 450°C and pressure of 1.50 × 107 Pa using an iron catalyst.N2(g) + 3H2(g) ⇋ 2NH3(g)ΔHr = –92 kJ mol–1a. Suggest
The information below gives the data for the reaction of hydrogen with iodine at 500°C.H2(g) + I2(g) ⇋ 2HI(g)The table shows the initial partial pressures and the partial pressures at equilibrium
Deduce the units of Kp for the following reactions:a. PCl5(g) PCl3(g) + Cl2(g)b. N2(g) + 3H2(g) 2NH3(g)c. 3Fe(s) + 4H2O(g) Fe3O4(s) + 4H2(g)
Ethanol can be manufactured by reacting ethene, C2H4, with steam.C2H4(g) + H2O(g) ⇌ C2H5OH(g)a. Write the equilibrium expression in terms of partial pressures, Kp, for this reaction.b. State the
The reaction below was carried out at a pressure of 10.00 × 104 Pa and at constant temperature.N2(g) + O2(g) ⇋ 2NO(g)The partial pressures of nitrogen and oxygen are both 4.85 × 104
This question is about the reaction:N2(g) + 3H2(g) ⇌ 2NH3(g) ΔHr = –92 kJ mol–1120.0mol of hydrogen gas are mixed with 40.0mol of nitrogen gas then pressurised. The mixture of gases is passed
a. Deduce the effect of increase in temperature on the value of Kc for the reaction:2NO2(g) + O2(g) 2NO(g)ΔHr = –115 kJ mol–1b. Explain why increasing the concentration of oxygen in this
a. Hydrogen chloride and ammonia both ionise in water:HCl + H2O H3O+ + Cl– equation 1NH3 + H2O NH4++ OH– equation 2i. State the name of the ion
This question is about the following reaction:9.20 g of ethanol are mixed with 12.00 g of ethanoic acid in an inert solvent. The total volume of solution is 250 cm3. The mixture is left to
Write equilibrium expressions for the following reactions and state the units of Kc.a. CO(g) + 2H2 ⇋ (g) CH3OH(g)b. 4HCl(g) + O2(g) ⇋ 2H2O(g) + 2Cl2(g)
a. Describe three characteristic features of chemical equilibrium.b. When 1mol of N2O4 gas is allowed to come to equilibrium with NO2 gas under standard conditions, only 20% of the N2O4 is
a. Predict the effect of increasing the temperature on the reaction:H2(g) + CO2(g) ⇋ H2O(g) + CO(g)ΔHr = +41.2 kJ mol–1b. In the reactionAg2CO3(s) ⇋ Ag2O(s) + CO2(g)increasing the temperature
Gaseous hydrogen and gaseous iodine react together to form hydrogen iodide.H2 + I2 ⇋ 2HIa. The graph shows how the amount of hydrogen iodide varies with time in a 1.00 dm3 container. The initial
a. Predict the effect of increasing the pressure on the following reactions:i. N2O4(g) 2NO2(g)ii. CaCO3(s) ⇋ CaO(s) + CO2(g)b. Predict the effect of decreasing the pressure on the reaction:2NO2(g)
The equilibrium between three substances, A, B and C is shown below.A(g) + B(g) ⇋ C(g)Initially there were 0.1mol of a and 0.2mol of B in the reaction mixture. a and B reacted together to produce
Use this reaction:CH3COOH(l) + C2H5OH(l) ⇋CH3COOC2H5(l) + H2O(l)Explain what happens to the position of equilibrium when:i. More CH3COOC2H5(l) is addedii. Some C2H5OH(l) is removed.b. Use this
Hydrogen, iodine and hydrogen iodide are in equilibrium in a sealed tube at constant temperature. The equation for the reaction is:H2 + I2 ⇋ 2HI(g) ΔHr = –96 kJ
A beaker contains saturated aqueous sodium chloride solution in contact with undissolved solid sodium chloride. Sodium ions and chloride ions are constantly moving from solid to solution and from

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