Standard Grade Homework Chemistry

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					                   Alva Academy
             Standard Grade Chemistry
                    Topics 8-15
                    Homework
Contents
Topic 8 Homework 1 …………           Pages 2, 3
Topic 8 Homework 2 …………           Page 4
Topic 8 Homework 3 …………           Page 5

Topic 9 Homework 1 …………           Pages 6, 7
Topic 9 Homework 2 …………           Page 8

Topic 10 Homework 1 …………          Pages 9, 10, 11
Topic 10 Homework 2 …………          Pages12, 13

Topic 11 Homework 1 …………          Pages 14, 15
Topic 11 Homework 2 …………          Pages 16, 17

Topic 12 Homework 1 …………          Page 18
Topic 12 Homework 2 …………          Page 19

Topic 13 Homework 1 …………          Page 20
Topic 13 Homework 2 …………          Pages 21, 22

Topic 14 Homework 1 …………          Pages 23, 24
Topic 14 Homework 2 …………          Pages 25, 26
Topic 14 Homework 3 …………          Page 27

Topic 15 Homework 1 …………          Page 28
Topic 15 Homework 2 …………          Pages 29, 30, 31




SG Chem Topics 8 to 15   Page 1                      Homework
                         Topic 8 – Homework 1
General Level
1. Using the apparatus below, a pupil electrolysed three
   different acid solutions.
                                       hydrogen


                                            acid solution
                                           carbon electrodes
      electrode A
                                           battery

     It was noted that a gas was given off at electrode A in all
     cases. The pupil suspects that the gas is hydrogen.
     a. What test would show that the gas is hydrogen? (2)
     b. Is A the positive or the negative electrode?         (1)
     c. Explain your answer to „b‟.                          (1)

2. X is a solution of an acid, Y is a solution of an alkali.
   Below are six statements which may apply to the
   solutions.
     A: It contains more H+(aq) ions than pure water.
     B: It contains more OH-(aq) ions than pure water.
     C: It has a pH less than 7.
     D: It has a pH equal to 7.
     E: It contains ions.
     F: It has a pH more than 7.
     a. Which statement is correct for both X and Y?           (1)
     b. Which two statements are correct for X
        but not for Y?                                         (2)




SG Chem Topics 8 to 15          Page 2                   Homework
Topic 8 – Homework 1 continued
General Level
3. Look at the oxides below and write the letter of the
   category that describes them best.
   A: Dissolves in water to give a pH less than 7.
   B: Dissolves in water to give a pH more than 7.
   C: Have no effect on the pH of water.
    a. sulphur dioxide       d. copper (II) oxide
    b. sodium oxide          e. iron (III) oxide
    c. carbon dioxide        f. barium hydroxide            (6)

Credit Level
4. Pure water is added to a solution with a pH 12.
   a. Which two ions are present in pure water?
   b. Which contains more hydroxide ions, the solution or
          pure water?
   c. What happens to the concentration of hydroxide ions
        in the solution as water is added?              (4)




  SG Chem Topics 8 to 15      Page 3                  Homework
                         Topic 8 – Homework 2
General Level
1. Calculate the formula mass for the following substances.
   a. CH4           c. carbon dioxide
   b. CaCO3         d. potassium carbonate              (4)
2. Calculate the mass of one mole of the following
   substances.
   a. MgO         c. calcium oxide
   b. K2O3        d. potassium hydroxide                   (4)

Credit Level
3. Write the formula then calculate the mass of each of the
   following substances.
   a. 2 moles of sodium chloride
   b. 0.25 moles of magnesium nitrate
   c. 0.2 moles of sodium hydrogen sulphate              (6)
4. Calculate the number of moles in each of the following
   substances.
   a. 36g of carbon
   b. 5.6g of carbon monoxide
   c. 8.2g of calcium nitrate                            (6)




SG Chem Topics 8 to 15          Page 4               Homework
                              Topic 8 – Homework 3
Credit Level
1. Calculate the number of moles of potassium hydroxide
    which must be dissolved to make each of the following
    solutions.
    a. 200cm3 of 0.5 mol/l
    b. 2 litres of 0.25 mol/l                             (2)

2.     Calculate the number of grams of substance which must
       be dissolved to make each of the following solutions.
       a. 50cm3 of 2 mol/l sodium hydroxide
       b. 25cm3 of 0.2 mol/l lithium nitrate                 (6)
3.     Calculate the concentration of each of the following
       solutions.
       a. 8g of sodium hydroxide in 250cm3 of solution
       b. 4g of copper (II) sulphate in 100cm3 of solution      (4)




     SG Chem Topics 8 to 15         Page 5                Homework
                         Topic 9 – Homework 1
General Level
1. a. Explain what is meant by a neutralisation
      reaction                                          (2)
   b. Name a substance found around the house that
      could be used to neutralise spilt battery acid.   (1)
   c. What will happen to the pH of the acid as it is
      neutralised?                                      (1)
   d. Explain why gardeners add lime to soil which is too
       acidic.                                          (2)

2. Name the products which would be formed in the
   reaction between each of the following solutions.
   a. potassium hydroxide and nitric acid                 (1)
   b. sodium hydroxide and sulphuric acid                 (1)

3. During manned flights in space rockets, carbon dioxide
   builds up in the air inside the cabin.
   a. Explain why the rockets also carry a supply of lithium
       hydroxide.                                        (2)
   b. What will happen to the pH of the lithium hydroxide
       solution during the flight?                       (1)

4. a. Which gas is produced when a metal carbonate
      reacts with a dilute acid?                   (1)
   b. Describe the test for this gas.              (1)

5. a. Which gas is produced when a metal reacts with
      dilute hydrochloric acid?                      (1)
   b. Describe the test for this gas.                (1)

6. Name all the products for each of the following reactions.
   a. calcium and hydrochloric acid                       (1)
   b. magnesium and sulphuric acid                        (1)


SG Chem Topics 8 to 15          Page 6              Homework
Topic 9 – Homework 1 continued

Credit Level
7. Look at the list of substance below.
          ammonium chloride           copper (II) oxide
          potassium sulphate          sodium oxide
           lithium nitrate            barium oxide
           zinc oxide
   Put these in a table with the headings alkalis, bases and
   salts.                                                    (7)




   SG Chem Topics 8 to 15      Page 7                  Homework
                         Topic 9 – Homework 2
Credit Level
1. Write balanced chemical equations for each of the
   following reactions.
   a. sodium hydroxide solution and hydrochloric acid. (2)
   b. magnesium oxide and nitric acid.                    (2)
   c. potassium carbonate solution and hydrochloric
      acid.                                               (2)
   d. aluminium and hydrochloric acid                     (2)
   e. copper (II) sulphate solution and sodium hydroxide
       solution.                                         (2)

2. a. What volume of hydrochloric acid (concentration 0.1
      mol/l) is required to neutralise 50cm3 of sodium
      hydroxide solution (concentration 0.2 mol/l)?        (2)
   b. What is the concentration of sulphuric acid if 50cm3
      are neutralised by 25cm3 of potassium hydroxide
      solution (concentration 1mol/l)?                     (2)
   c. What volume of nitric acid (concentration 2mol/l) is
      required to neutralise 20cm3 of sodium hydroxide
      solution (concentration 0.5mol/l)?                   (2)
   d. What is the concentration of hydrochloric acid if
      12.6cm3 neutralises 20cm3 of potassium hydroxide
      solution (concentration 0.1mol/l)?                   (2)
   e. What is the concentration of sulphuric acid if 17.3cm3
      neutralises 25cm3 of sodium hydroxide solution
      (concentration 0.5mol/l)?                            (2)




SG Chem Topics 8 to 15          Page 8              Homework
                              Topic 10 Homework 1
General Level
1. One of the most widely used batteries is known as the dry
   cell. This is used in portable radios, torches and toys.
   a. Explain why the dry cell eventually has to be re-
       placed.                                               (1)
   b. What is the purpose of the ammonium chloride paste
       in the dry cell?                                      (1)
   c. Explain why the ammonium chloride is in the form of
       a paste and not completely “dry”.                     (2)
   d. State one advantage of a nickel-cadmium battery
       compared to a dry cell.                               (1)
   e. In a house it is cheaper to run the radio from the
       mains or the batteries?                               (1)

2.
                               Electron flow
                                      V
               A                                    C
                                      E


              B                                     D



     a. Using magnesium, copper, magnesium sulphate
        solution and copper sulphate solution, state what A,
        B, C and D must be to give a flow of electrons in the
        direction shown.                                        (2)
     b. i. What is E on the diagram known as?                   (1)
        ii. Why is it necessary?                                (1)
        iii. Why is sodium chloride solution suitable to be
             used in E, but sugar solution not?                 (2)


     SG Chem Topics 8 to 15            Page 9           Homework
Topic 10 – Homework 1 continued
General Level
3. Using the apparatus below, the following results were
   obtained.
   a. What name is given to this kind of series of metals
       arranged from voltmeter readings?                 (1)

          V                                   Filter paper
                                              soaked in sodium
                                              chloride solution
              Test metal     copper

              Test metal   Voltmeter reading (volts)
              lithium                 2.9
              Sodium                  2.4
              Magnesium               1.6
              Iron                    0.5
              Tin                     0.4
              Copper                  0.0
              silver                 -0.4

     b. Why doesn‟t magnesium ribbon react with sodium
         sulphate solution?                                   (1)
     c. When magnesium ribbon is added to copper
         sulphate solution, the ribbon starts to break up at the
         surface, a brown solid forms, and the solution
         eventually becomes colourless. Explain these three
         observations.                                        (3)
      d. Suppose the copper block was replaced by a block
         of tin. What would the reading on the voltmeter be if
         the test metal was iron?                             (1)
     e. Which metal could be used as the test metal to give
         a voltmeter reading of approximately 1.2 volts? (1)



SG Chem Topics 8 to 15       Page 10                    Homework
 Topic 10 – Homework 1 continued
 Credit Level
 4.

                                V

    Carbon                                      Carbon
  electrode A                                 electrode B



  Potassium                                   Iron(III) chloride
iodide solution                                   solution



                          Cotton wool plug

      The reaction occurring at electrode B is:
               Fe3+(aq) + e- ───> Fe2+(aq)
      a. Name the type of reaction occurring at electrode B
                                                            (1)
      b. In which direction do the electrons flow through the
         meter?                                             (1)
      c. What product is formed from iodide ions at electrode
         A?                                                 (1)




 SG Chem Topics 8 to 15             Page 11                   Homework
                     Topic 10 – Homework 2
Credit Level

1. Decide which of the following reactions involve:
             O: oxidation          R: reduction
      (You may find it helpful to use the data booklet.)
   a. Zn2+(aq) + 2e- ───> Zn(s)
   b. Ag(s) ───> Ag+(aq) + e-
   c. Br2(l) + 2e- ───> 2Br-(aq)
    d.    SO32-(aq) + H2O ───> SO42-(aq) + 2H+ + 2e-
    e.    nickel (III) ───> nickel (II)
    f.    copper atoms ───> copper ions                    (6)

2. This question refers to the addition of a metal to a
   solution containing ions. In each case decide whether
               Yes: a reaction will take place.
             No: a reaction will NOT take place.
   a. copper added to silver nitrate solution              (1)
   b. magnesium added to sodium sulphate solution          (1)
   c. iron added to dilute hydrochloric acid               (1)
   d. copper added to dilute sulphuric acid solution       (1)
   e. iron added to copper(II) nitrate solution            (1)

3. When copper metal is added to a solution of silver(I)
   nitrate a displacement reaction occurs forming silver
   metal and copper(II) nitrate.
   a. Write a balanced equation for the reaction.        (2)
   b. How many moles of silver are displaced by 1 mole of
        copper?                                          (1)
   c. What mass of silver will be displaced by 3.2g of
        copper?                                          (2)




SG Chem Topics 8 to 15       Page 12                 Homework
   Topic 10 – Homework 2 continued
Credit Level
4. a. C + O2 ───> CO2
      What weight of carbon dioxide is formed when 6g of
      carbon is burned completely?                       (2)
   b. 2 Mg + O2 ───> 2 MgO
      What weight of magnesium oxide is produced when 24g
      of magnesium burns?                                (2)
   c. 2 H2 + O2 ───> 2 H2O
      What weight of hydrogen is needed to give 9g of
      water?                                             (2)

5. A compound Z is found to contain 54.5% carbon, 9.1%
   hydrogen and 36.4% oxygen and have a formula mass of
   88amu.
   a. Calculate the empirical formula of Z.             (4)
   b. What is the molecular formula of Z?               (1)




   SG Chem Topics 8 to 15   Page 13                 Homework
                     Topic 11 – Homework 1
General Level
1. Each of the following experiments were set up to
   investigate the rate of four metals, W, X, Y and Z, with
   dilute hydrochloric acid.




             W            X             Y               Z

a. Place the four metals in order of reactivity. Start with the
   most reactive.                                             (1)
b. State three factors that must be kept the same for the
   comparison to be a fair one.                               (3)
c. Which gas is produced in the reaction of a metal with
   dilute hydrochloric acid?                                  (1)
d. Write a word equation for the reaction of magnesium with
   dilute hydrochloric acid.                                  (1)
e. Write an equation for the reaction using symbols and
   formulae.                                                  (1)




SG Chem Topics 8 to 15        Page 14                  Homework
Topic 11 – Homework 1 continued
General Level
2. The results of experiments with four metals W, X, Y, Z
   and their compounds are summarised in the table below.

     Metal         Column 1              Column 2            Column 3
               Reaction of metal     Action of heat on   Reaction of metal
                with dilute acid       metal oxide        with cold water
       W       hydrogen evolved        no reaction       hydrogen formed
       X          no reaction          no reaction          no reaction
        Y      hydrogen evolved        no reaction       very slow reaction
        Z         no reaction         metal formed          no reaction

     a. State what information about the order of reactivity
         of the metals can be obtained from:
         i. Column 1 alone                                      (1)
         ii. Column 2 alone                                     (1)
     b. Now use ALL the information to put the metals into
         an order of reactivity placing the most active first. (1)
     c. Suggest a name for each metal W, X, Y and Z.            (1)

3. An unknown metal was found to be more reactive than
   sodium. Which of the following predictions about the
   metal is likely to be correct?                       (1)
   A. It will react readily with oxygen in the air.
   B. It should be stored under water.
   C. Its compounds will be unstable.
   D. It will be obtained from its oxide by heating
         with carbon.




SG Chem Topics 8 to 15             Page 15                       Homework
                     Topic 11 – Homework 2
General Level
1. Name one metal which can be extracted by each of the
   methods below.
   a. By heating alone.
   b. By heating with carbon, but not by heating alone.
   c. By using electricity but not by heating with carbon. (3)

2. Iron is produced from its ore using a process called
   smelting. The chemical reactions take place in a huge
   tower.
   a. What name is given to the tower?                    (1)
   b. The following reactions take place in the tower. Write
       a word equation for each.
       i. The burning of coke.                            (1)
       ii. The production of carbon monoxide gas.         (1)
       iii.   The formation of iron from its ore.         (1)

Credit Level
3. A pupil was asked to investigate three metal oxides LO,
   M2O, and NO. On heating strongly LO broke down into a
   metal L and oxygen. The other two oxides did not break
   down.
   a. From this evidence what can be deduced about the
      reactivity of metal L.                             (1)
   b. How could you test M2O and NO in order to find
      out which was the more reactive of the metals M
      and N?                                             (1)

4. Calculate the simplest (empirical) formula for the
   following compounds from the percentage composition
   by mass.
   a. 25% magnesium, 75% chlorine
   b. 33% calcium, 27% sulphur, 40% oxygen             (4)


SG Chem Topics 8 to 15       Page 16                 Homework
Topic 11 – Homework 2 continued
Credit Level
5. A container when empty had a mass of 60g. An oxide of
   lead was added and the mass of the container plus the
   oxide was 120g. Carbon monoxide gas was then passed
   over the heated oxide. During the reaction lead oxide
   was reduced to lead. At the end of the reaction the mass
   of the container plus the lead metal was 112g.
   What is the simplest formula for the oxide?            (2)




SG Chem Topics 8 to 15     Page 17                  Homework
                     Topic 12 – Homework 1
General Level
1. a. Apart from iron, what two substances are necessary
      for rusting to occur?                            (2)
   b. When iron rusts, what happens to the iron atoms? (1)

2. a. How does ferroxyl indicator help to compare the rates
      of corrosion?                                       (1)
   b. Explain why salt in the water speeds up the rate of
      corrosion whereas glucose does not.                 (1)

Credit Level
3. Corrosion involves atoms at the surface of a metal losing
   electrons and changing into metal ions.
   a. State the name of this kind of reaction.            (1)
   b. Write ion-electron equations to show what happens to
      the metal atoms during the corrosion of:
      i. iron
      ii. zinc                                            (2)




SG Chem Topics 8 to 15       Page 18                Homework
                     Topic 12 – Homework 2
General Level
1. What is the name given to each of the following
    processes?
a. Iron is dipped into molten zinc to give it a protective layer
    against corrosion.
b. Scrap magnesium is used to protect an iron structure
    against corrosion.
c. Electrolysis is used to coat iron with another metal.       (3)

Credit Level
2. a. Write ion-electron equations for each of the reactions
      which occur when iron is corroded by acid.          (2)
   b. Explain why galvanising does not protect iron
      permanently from corrosion by acid.                 (1)

3. Three experiments were set up outside to investigate the
   corrosion of “tin” cans. The three cans, A, B and C are
   described below.
   A: Iron can.
   B. Iron can that is coated with tin.
   C: Iron can that is coated with tin, but the tin coating is
       scratched so exposing the iron underneath.
   a. In which experiment will the iron not rust? Explain. (2)
   b. In which experiment will the iron rust fastest?
       Explain.                                                (2)

4. Both zinc and tin are used to protect iron and steel
   containers from corrosion. Metal dustbins are made from
   iron which has been dipped into molten zinc; cans for
   food are tin-plated.
   a. Explain why zinc is preferred to tin for protecting
       dustbins. (give two reasons).                      (2)
   b. Explain why food cans are tin plated.               (1)


SG Chem Topics 8 to 15       Page 19                    Homework
                     Topic 13 – Homework 1
General Level
1. Consider the list of substances below:
      polystyrene, rubber, nylon, polythene, bakelite,
      starch, perspex, polypropene, terylene, wool
   Put these in a table with the headings natural and
   synthetic.                                             (5)

2. Explain the purpose of each of the following:
   a. The Teflon skin on some frying pans.
   b. The PVC skin on some wallpapers.
   c. The PVC covering on electric wires.                 (3)

3. Thermosetting plastics have different properties form
   thermoplastics. Explain what is meant by:
   a. Thermosetting plastic.
   b. Thermoplastic                                      (2)


Credit Level
4. Many plastics burn or smoulder to give off toxic fumes.
   Name a plastic which can give off:
a. Carbon monoxide
b. Hydrogen chloride
c. Hydrogen cyanide                                        (3)




SG Chem Topics 8 to 15       Page 20                 Homework
                     Topic 13 – Homework 2
General Level
1. Consider the monomers below:

           H             H                H    H    H       H

               C═C               H        C    C    C       C       H

           H             H                H    H    H       H

          H                  H                       H      H

               C═C           C   H             Cl    C      C       Cl

          H         H        H                          H       H

                  ethane                            styrene
                  octane                            vinyl chloride
                  C3H8                              C2F4
                  C2H4Br2                           C3H5Cl

    Draw a table and place each of the substances in the
    appropriate column: able to undergo polymerisation or
    not able to undergo polymerisation.


Credit Level
2. Polypropene is used to make kitchen items.
   a. Name the monomer unit.
   b. Draw the full structural formula of the monomer.
   c. Draw the structure of part of the polypropene chain to
      show how three monomer units have joined together.
                                                         (3)



SG Chem Topics 8 to 15               Page 21                            Homework
Topic 13 – Homework 2 continued
Credit Level
3. The diagram shows part of the structure of a molecule of
   Orion.

             CH2         CH   CH2   CH    CH2   CH

                         CN          CN         CN

    a. Draw the structural formula for the repeating unit in
       Orion.                                               (1)

    b. Draw the structure of the monomer used to make
       Orion.                                         (1)




SG Chem Topics 8 to 15          Page 22               Homework
                       Topic 14 – Homework 1
General Level
1. Fertilisers are compounds which restore to the soil the
   essential elements for plant growth.
   a. Name the three elements which are restored to the
       soil through use of fertilisers.                    (1)
    b. Explain why woodland growth can be rapid while
        farmland requires large quantities of fertilisers. (1)

2.    The flow chart shows part of the nitrogen cycle.

         Synthetic          Nitrates
         fertilisers         in soil

     Industrial process

         Atmospheric               Plants
           nitrogen
                                            Y    Natural
                X
                                                fertilisers
          Peas, beans,            Animals
             clover
     a. Explain what is meant by:
         i. Synthetic fertiliser.
        ii. Natural fertiliser.                             (2)
     b. Give an example of each.                            (1)
     c. What is process X called?                           (1)
     d. What types of living thing act on dead material to
         bring about process Y?                             (1)
     e. Crop yields have increased considerably in the last
         50 years. Give a reason for this increase.         (1)
     f. Give an example of the effect of synthetic fertilisers
         on river water.                                    (1)


SG Chem Topics 8 to 15          Page 23                   Homework
Topic 14 – Homework 1 continued
General Level
3. At the turn of the century a team of scientists led by Fritz
   Haber discovered a cheap way to make an important
   compound for the fertiliser industry. This is now called the
   Haber process.
   a. i. Name the compound which Haber produced.             (1)
       ii. Name the reactants in the process.                (1)
       iii. State where each reactant comes from.            (1)
   b. Which catalyst is used for the reaction?               (1)
   c. State two other conditions that are necessary for a
       successful yield of the compound.                     (2)

Credit Level
4. Urea, CO(NH2) 2, and ammonium nitrate, NH4NO3, are
   both fertilisers that supply nitrogen.
   Find the most useful fertiliser by calculating the
   percentage mass of nitrogen in each.               (3)




SG Chem Topics 8 to 15      Page 24                    Homework
                         Topic 14 – Homework 2
General Level
1. The manufacture of nitric acid is an important process in
   the chemical industry.

        Gas Z       Platinum   Oxides of nitrogen    Nitric acid
                       air
     a. What name is given to the process?                   (1)
     b. Name gas Z.                                          (1)
     c. State the kind of chemical reaction taking place in the
        first stage of the process                           (1)
     d. What role does the platinum play?                    (1)

2. Nitrate fertilisers are made from nitric acid
          Nitric acid + A ───> potassium nitrate
   a. Name reagent A                                       (1)
   b. Name the other product of this reaction.             (1)
   c. Write a balanced equation for the reaction.          (2)
   d. Name the kind of reaction which is taking place. (1)
   e. Give two reasons why nitrates are useful fertilisers.(1)

Credit Level
3. Ammonium sulphate is a fertiliser. Write a balanced
   equation for the reaction of ammonia with sulphuric acid
   to form ammonium sulphate.                           (2)




SG Chem Topics 8 to 15          Page 25                 Homework
Topic 14 – Homework 2 continued
Credit Level
4. A student carried out two experiments on compound X.
                                                        Damp pH paper
   Dilute
                                                        Sodium hydroxide
   sulphuric acid
                                                        solution
                                 Lime water
      X                                                  X
                                                 Heat
     A colourless gas was given off and       A gas was given off that
     the lime water became milky              turned the pH paper blue
     a.   Name the gas given off in the first experiment. (1)
     b.   Name the gas given off in the second experiment (1)
     c.   Name compound X.                                 (1)
     d.   Write a balanced equation to show the reaction of X
          with sulphuric acid.                             (1)




SG Chem Topics 8 to 15          Page 26                      Homework
                     Topic 14 – Homework 3
Credit Level

Calculations from Equations
1. CaCO3 ───> CaO + CO2
   What mass of carbon dioxide is produced by the
   decomposition of 10g of calcium carbonate?            (3)

2. C2H4 + 3O2 ───> 2CO2 + 2H2O
   What mass of water vapour is produced on burning 7g of
   ethene?                                           (3)

3. What mass of hydrogen is required to completely reduce
   10g of copper (II) oxide to copper?                (3)

4. What mass of hydrogen is obtained when 6.125g of
   magnesium reacts with excess dilute hydrochloric
   acid?                                            (3)

5. What mass of propane is obtained when 7g of propene
   (C3H6) reacts with hydrogen?                      (3)




SG Chem Topics 8 to 15       Page 27                Homework
                     Topic 15 – Homework 1
General Level
1. Starch and glucose are both carbohydrates.
   a. Name the elements which are found in a
      carbohydrate.                                     (1)
   b. Explain what is seen when a beam of light is passed
      through
      i. glucose solution
      ii. starch in water                               (2)

Credit Level
2. Consider the list of carbohydrates below.
             glucose, maltose, fructose, sucrose
   a. Name the carbohydrates which are:
      i. monosaccharides
      ii. disaccharides                               (2)
   b. Write the molecular formula for:
      i. monosaccharides
      ii. disaccharides                               (2)
   c. Name the isomer of:
      i. glucose
      ii. maltose                                     (2)
   d. Which carbohydrate does NOT give a positive result
      to the Benedicts test?                          (1)

3. A glucose monomer can be presented as shown:

         HO ────         G   ──── OH

     a. Use the representation to draw three units in the
        starch polymer chain.                             (1)
     b. What kind of polymerisation takes place when starch
        is formed from glucose?                           (1)



SG Chem Topics 8 to 15        Page 28                Homework
                     Topic 15 – Homework 2
General Level
1. The diagram below represents the process by which
   energy is produced in animals.




     a. Name the process.                               (1)
     b. Name the gases X and Y.                         (1)
     c. Give three examples of how the energy produced can
        be used by animals.                             (3)

2. a. A carbohydrate was tested as shown in the diagram
      below.
             Test 1                               Test 2
                          Warm water                       Iodine
                                                           solution
                         Carbohydrate +
                         benedicts solution                 Carbohydrate

         Result: no change in the             Result: iodine solution
         colour of the Benedicts              did not change colour.
         solution.

         Suggest a name for the carbohydrate which was
         tested.                                                  (1)


SG Chem Topics 8 to 15            Page 29                   Homework
                Topic 15 – Homework 2 continued
General Level
2. b.       Test 3                                     Test 4
                           hot water                        iodine
                                                            solution
                          carbohydrate
                          in water +                        carbohydrate
                          dilute
                          hydrochloric
                          acid

         Result: after the solution           Result: iodine solution
         was neutralised, Benedicts           turned blue/black.
         solution gave an orange
         precipitate.

         i. Name the carbohydrate used in tests 3 and 4.          (1)
         ii. Name the carbohydrate produced by the
             reaction in test 3.                                  (1)

3. Study the flow diagram below and answer the questions
   which follow:
     glucose
     solution
                     fermenter    fermented     separator
                                     liquid
     yeast
                         gas X                waste     alcohol
                                              liquid
     a. Name gas X.                                         (1)
     b. What kind of substance, present in yeast, acts as a
        catalyst for the reaction?                          (1)
     c. Name the alcohol produced by this process.
     d. How is the alcohol separated from the waste liquid?
                                                            (1)
SG Chem Topics 8 to 15           Page 30                    Homework
Topic 15 – Homework 2 continued

Credit Level
4. The production of ethanol from glucose is normally
   carried out at a temperature around 40°C.
   a. Write a balanced chemical equation for the
       reaction.                                             (2)
   b. i. Would the reaction be speeded up by boiling?        (1)
      ii. Explain your answer to b. i..                      (1)
   c. Explain why there is a limit to the concentration of
      ethanol obtained in this reaction.                     (1)




SG Chem Topics 8 to 15      Page 31                   Homework

				
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