NATIONAL 5 - CHEMISTRYCHEMISTRY IN SOCIETY

HOMEWORK

 "Let them who has earned it bear the reward". – Whitburn Academy (est. 1969) –school motto

HOMEWORK

DEADLINE DATE

SCORE TEACHER COMMENTS

1 18 Metals and their reactivity (reaction with oxygen, water and acid) -

2 18 Metals (Extraction from their ores) –

3 24 Metals (electrochemical cells, redox and fuels cells) –Grade -

4 18 Properties of plastics (addition and condensation) –

5 7 Properties of plastics (Natural polymers) –Grade -

6 15 Fertilisers (Haber Process) -

7 22 Fertilisers (Oswald Process) -

8 11 Nuclear chemistry (types of radiation and nuclear equations) -

9 27 Nuclear chemistry (half-life and nuclear equations) – Grade -

10 9 Chemical analysis (methods of monitoring the environment using chemistry) –Grade - Grade -

HOMEWORK 1 – METALS AND THEIR REACTIVITY(Reaction with oxygen, water and acid)

Reaction with oxygenMETAL + OXYGEN METAL OXIDEReaction with waterMETAL + WATER METAL HYDROXIDE + HYDROGENReaction with dilute acidMETAL + ACID SALT + HYDROGEN

Q1) For each of the following reactions give:a) a balanced chemical equation b) an equation showing ions and state symbols

magnesium and oxygen

(2)

Aluminium and oxygen

(2)

Lithium and water

(2)

Calcium and water

(2)

Magnesium and acid

(2)

Calcium and acid

(2)

Q2) Which of the following metals does not react with dilute acid? A) Magnesium B) Calcium C) Copper D) Zinc

(1)Q3) Which of the following diagrams could be used to represent the structure of a metal. Circle the letter to indicate your choice.

(1)Q4) Metallic bonds are due to:

A) A shared pair of electrons B) An attraction between positive ions and negative ions

C) An attraction between positive ions and delocalised electrons D) An attraction between negative ions and delocalised electrons

(1)Q5) Three metals X, Y and Z were reacted with dilute acid and water. The results are shown in the table below. Using the table, which of the following shows the metals in order of increasing reactivity? Circle a letter to indicate your answer.

a) XYZ B) YXZ

C) ZXY D) ZYX(1)

Q6) Gold is a very soft metal. In order to make it harder, goldsmiths mix it with silver. The quality of gold is indicated in carats. The graph below shows information about the quality of gold.

a) What is the percentage of silver in an 18 carat gold ring?(1)

b) Calculate the mass of silver in an 18 carat gold ring weighing 6g. (1)

HOMEWORK 2 – METALS(Extraction from their ores)

Percentage Composition Chemists often need to know the percentage of each element in a compound. This is called the percentage composition of the compound. Example: calculate the percentage of iron within iron (iii) oxide, (Fe2O3).

Q1) Which of the following metals can be extracted from its oxide by heat alone?

A) Aluminium B) Iron C) Silver D) Zinc(1)

Q2) Which of the metals must be obtained from its ore (oxide) by using electrolysis?

A) Aluminium B) Iron C) Silver D) Zinc

(1)

Q3) Which of the metals would need to be heated with carbon to remove it from its ore?

A) Aluminium B) Iron C) Silver D) Zinc(1)

Q4) Calculate the percentage by mass of iron in the ore magnetite, formula Fe3O4

(3)Q5) Calculate the percentage by mass of aluminium in the compound alumina Al2O3.

(3)Q6) Galena is an ore containing lead sulphide, PbS. a) What is the charge on the lead ion in this compound?

(1)b) Calculate the percentage by mass of lead in galena, PbS.

(3)

Metal extraction involves reductionMetal oxides (ores) are said to be reduced to the metal during extraction. This is because the metal ion in the oxide accepts electrons when the metal is formed. For example, in the extraction of zinc from zinc oxide, the reduction equation is:

Zinc oxide + carbon zinc + carbon dioxide

Zn2+O2- + C Zn + CO2

REDUCTION IS GAIN OF ELECTRONS Zn2+

+ 2e- Zn

Q7) Using the reduction equation for zinc to help you; write similar equations for the reduction of: a) Iron (iii) ions to form iron metal.

(1)b) Silver (i) ions to form silver metal.

(1)c) Magnesium oxide to for magnesium metal.

(1)d) Iron (ii) ions to form iron metal.

(1)Q8) A metal can be extracted from its ore by heating the ore with carbon but not by heating the ore on its own. The position of the metal in the reactivity series is most likely to be between (you may wish to use your data booklet):

A) Zn and Mg B) Mg and K C) Zn and Cu D) Cu and Au (1)

HOMEWORK 3 – METALS

(Electrochemical cells, redox and fuels cells) To produce an electrical current you will need three things:

An electrolyte (ionic substance) Two different kinds of metal (e.g. zinc and copper)

Complete circuit to allow electron

Luigi Galvani (1737 – 1798)

During the 1780’s, biologist Luigi Galvani performed experiments at the University of Bologna involving frogs. While cutting a frog’s leg, Galvani’s steel scalpel touched a brass hook that was holding the leg in place. The leg twitched. Further experiments confirmed this effect, and Galvani was convinced that he was seeing the effects of what he called animal electricity, the life force within the muscles of the frog. At the University of Pavia, Galvani’s colleague Alessandro Volta was able to reproduce the results, but was sceptical of Galvani’s explanation.

By experiment Volta found that it was the two dissimilar metals, not the frog’s leg that produced the electricity. The frog’s leg was just an indicator of presence of the electricity.

Mary Shelley the author of Frankenstein read Galvani’s paper and these phenomena of electricity and movement of the frog’s legs inspired her novel.

Alessandro Volta (1745 –1827)

In 1800, after extensive experimentation, he developed the voltaic pile. The original voltaic pile consisted of a pile of zinc and silver discs and between alternating discs, a piece of cardboard that had been soaked in saltwater. A wire connecting the bottom zinc disc to the top silver disc could produce repeated sparks. No frogs were injured in the production of a voltaic pile. Volta built different piles using thirty, forty or sixty elements. This enabled him to study the action of the pile on the electric fluid, depending on the number of elements, and he confirmed that the electric shock increased in intensity with the number of elements used in the pile. If more than twenty elements were used, it became painful. The first piles constructed by Volta comprised alternating zinc and copper discs. Each was separated from its neighbour by a piece of cloth or card dampened by an acid solution. The column was supported by three vertical glass rodsRedox Equations

Wherever a reaction involves both oxidation and reduction, it is called a redox reaction; electrons lost by one substance during oxidation are gained by another substance during reduction. For example: sodium reacting with chlorine.

2Na(s) + Cl2(g) 2NaCl(s)

2Na 2Na+ + 2e- (oxidation) Cl2 + 2e- 2Cl- (reduction)2Na + Cl2 2Na+Cl- (redox) An Oxidising agent is an electron

acceptor...so is itself reduced. Look above chlorine is an oxidising agent because it was reduced i.e. accepted electrons.

A Reducing agent is an electron donor...so is itself oxidised. Look above sodium is a reducing agent because it was oxidised i.e. donated electrons

DISPLACEMENT REACTIONS

Cu2+SO42- + Zn(s) Zn2+SO42- + Cu(s)

Au + Zn2+SO42- - The less reactive metal can’t displace the more reactive zinc from its compound

Q1) in the cell shown, electrons flow through

A) The solution from tin to zinc B) The connecting wire from tin to zinc

C) The solution from zinc to tin D) The connecting wire from zinc to tin

(1)Q2) Four cells were made by joining copper, iron, tin and zinc to silver

Redox Equations Wherever a reaction involves both oxidation and reduction, it is called a redox reaction; electrons lost by one substance during oxidation are gained by another substance during reduction. For example: sodium reacting with chlorine.

2Na(s) + Cl2(g) 2NaCl(s)

2Na 2Na+ + 2e- (oxidation) Cl2 + 2e- 2Cl- (reduction)2Na + Cl2 2Na+Cl- (redox) An Oxidising agent is an electron

acceptor...so is itself reduced. Look above chlorine is an oxidising agent because it was reduced i.e. accepted electrons.

A Reducing agent is an electron donor...so is itself oxidised. Look above sodium is a reducing agent because it was oxidised i.e. donated electrons

The voltages are shown in the table. Which line in the table shows the voltage of the cell containing copper joined to silver? You may wish to use your data booklet to help you.

(1)Q3) The ion-electron equation for the oxidation and reduction steps in the reaction between magnesium and silver(i) ions is:

Mg Mg2+ + 2e Ag+ + e Ag

The overall redox equation is

(1)Q4) Ag+ + e- Ag This ion electron equation above represents the

A) Reduction of silver (i) ions B) Reduction of silver (ii) ions C) Oxidation of silver (i) ions D) Oxidation of silver (ii) ions (1)

Q5) Four cells were made by joining magnesium, aluminium nickel and zinc to lead. The voltages are shown in the table.

Cell Voltage (V)A 0.3B 1.0C 1.1D 1.2

Which line in the table below shows the voltage of the cell containing magnesium joined to lead? You may wish to use your data booklet. Circle the letter in the table to indicate your choice.

(1)Q6) In which of the following test tubes will a reaction occur?

(1)Q7) Which metal will displace zinc from a solution of zinc sulphate?

A) Iron B) Magnesium C) Silver D) Tin (1)

Q8) Write a complete redox equation showing ion-electron equations for the oxidation and reduction reactions when iron is added to copper (ii) sulphate.

(2)

Q9) The voltage obtained when different pairs of metal strips are connected in a cell varies and this leads to the electrochemical series. Using the apparatus below, a student investigated the electrochemical series. Copper and four other metal strips were used in this investigation.

The results are shown.

a) Which of the metals used is the highest in the electrochemical series?

(1)b) Circle the correct metal to complete the sentence. Connecting metal to metal 2 would produce the largest voltage.

(1)c) What would be the reading on the voltmeter if both strips of metal were copper?

(1)d) Why can sucrose (C12H22O11) not be used as an electrolyte

(1)Q10) A student investigated if the type of electrolyte used affects the voltage produced in a cell.

a) Complete the labelling of a second cell which could be used to compare the effect of changing the electrolyte from sodium chloride to hydrochloric acid.

(1)b) What is done during an investigation to ensure the results obtained are accurate?

(1)

c) Within the first cell will the electrons flow from?A) Copper to iron B) iron to copper

(1)Q11) Cells can also be made in which both metals and non metals are used.

The ion electron equation taking place at the carbon electrode is:

a) What term can be used to describe the reaction taking place at the carbon electrode?

(1)b) On the diagram, clearly mark the path and direction of electron flow.

(1)Q12) The cell shown below was set up by a student in the lab.

a) What is the purpose of the ion bridge?

(1)b) Name a metal that could replace the zinc electrode to give a higher voltage?

(1)Q13) Iron displaces silver from silver (i) nitrate solution. The equation for the reaction is:

Fe(s) + 2Ag+ (aq) + 2NO3-(aq) Fe2+(aq) + 2Ag(s) + 2NO3-(aq)a) Write the ion-electron equation for the reduction step in the reaction. You may wish to use your data booklet.

(1)b) This reaction can also be carried out in a cell. Complete the three labels on the diagram.

(1)Hydrogen Fuel Cells and Rechargeable batteries.

Q14) a) State an advantage of using fuel cells to power cars.

(1)b) Write the ion electron equation for the formation of hydrogen ions. You may wish to use your data booklet to help you.

(1)

Write a brief report on the chemistry behind rechargeable batteries and the new technology of fuel cells. Discuss the uses of this technology and any environmental or social impact they will have.

HOMEWORK 4 – PROPERTIES OF PLASTICS

(Addition and condensation)

Q1) The structure below shows a section of an addition polymer.

Which of the following molecules is used to make this polymer?

(1)

Q2) Polyamides and polyesters are always made from monomers A) which are unsaturated B)with one functional group per molecule C) containing a benzene ring D) with two functional groups per molecule

(1)

Q3) Polyethene terephthalate (PET) is used to make plastic bottles which can easily be recycled by heating and reshaping. A section of the PET structure is shown.

Which line in the table best describes PET?

(1)

Q4) Some waterproof clothing contains a thin layer of plastic PTFE.

a) Draw a section of the PTFE polymer, showing three monomer uints joined together. The monomer is shown above.

(1)

b) Based on the monomer for PTFE shown above what type of polymerisation would produce this polymer?

(1)c) PTFE is heated and then reshaped to make thin layers. What term is used to describe a plastic which can be heated and reshaped?

(1)d) Name a toxic gas produced when PTFE is burned.

(1)Q5) Synthetic nappies contain hydrogel polymers which attract and absorb water molecules.

a) The above is a part of the structure of a hydrogel polymer. Draw the monomer below.

(1)b) The diagram below shows how water molecules are attracted to the hydrogel.

HOMEWORK 5 – PROPERTIES OF PLASTICS

Name and circle the functional group present in the hydrogel structure that allows it to attract water molecules.

(1)Q6) Part of the structure of an addition polymer is shown below. It is made using two different monomers.

Which pair of alkenes could be used as monomers for this polymer? A) ethane and propene B) ethene and buteneC) Propene and butene D) Ethene and pentene(1)

Q7) Poly(ethanol) is one of the substances used to cover dishwasher tablets.

The monomer of the polyethanol polymer is shown above.a) Name the functional group present in this polymer.

(1)

b) Draw the structure of the repeating unit in poly(ethanol)

(1)c) Name the type of polymerisation that takes place to form poly(ethanol).

(1)d) Draw a section of the polymer showing at least three repeating units.

(1)Q8) Kevlar is a synthetic fiber that can be used to reinforce the walls of tires.

a) Kevlar is made from the monomers above.(i) When these two monomers combine, hydrogen chloride (HCl) is also produced. Draw the structure of the repeating unit formed from these two monomers.

(1)(ii) Name the type of polymerisation that takes place to form Kevlar.

(1)b) The polymer shown can be used to produce belts for car engines but increasingly car manufactures are using Kevlar as a replacement.

The polymer shown is an example of a polyester. Draw the structural formula of the two monomers that were used to produce this polymer.

(2)

HOMEWORK 5 – NATURAL POLYMERS (Natural polymers)

Q1)

a) What is the electron arrangement for a calcium ion, Ca2+ ?

(1)

b) CGRP is formed from different amino acids. A short sequence of CGRP is shown.

i) Circle a peptide (amide) link (1)

ii) Draw one of the amino acids used to form the above section.

(1)Q2) Which of the following groups can react together to form a peptide (amide) link?

(1)

Q3) The enzyme RuBisCo is one of the most abundant enzymes on earth. It contains lysine at its active site.

a) Lysine contains two different functional groups, circle and identify what functional groups it has on the diagram.

(2)b) Complete the equation to show the structure of the other product formed when two molecules of lysine react. (hint: it is a condensation reaction forming an amide link and water will be released).

(1)

Write a short report on the underlying polymer chemistry in nature. Discuss how proteins form and what type of polymerisation this is. Explore the chemistry of DNA and examine the chemistry behind this polymer. Remember it is only to be brief. (structural diagrams with labels to be included).

HOMEWORK 6 – FERTILISERS

HABER PROCESS

Farmers throughout the world use millions of tonnes of nitrogen-containing fertilisers (NH4NO3, NH4PO4, etc.). The Haber process was invented by a German chemist, Fritz Haber, along with the engineer Carl Bosch in 1908. Plants need NPK (nitrogen, potassium and phosphorous) to make proteins and for healthy growth. They can only obtain this through soluble salts containing these elements that must be soluble. This is because plants will absorb them in the water through their roots in the soil. This is why farmers spray fertilisers on their field. They can be more organic

and use horse manure etc. but with the demand for crop production – population increasing – then artificial fertilisers are essential.Both these gentleman pioneered the process of reacting nitrogen (N2) with hydrogen (H2) to make ammonia gas (NH3).

This is easier than it sounds because nitrogen is a very un-reactive gas due to three covalent bonds. The Haber process allowed a high percentage of ammonia to be produced. It provided a solution to the high energy required to break the covalent bonds in the nitrogen to allow it to react and produce ammonia (NH3) more economically. Ammonia (NH3) gas can be converted easily into soluble ionic compounds that can be used in fertilisers. Hydrogen is obtained from methane (CH4) that comes from

crude oil. Nitrogen is obtained from the air (~79% of the air is N2) An iron catalyst is used to speed up the reaction. The gases are put under high pressure and a moderately high

temperature. As the ammonia gas is formed, it is removed by cooling it to

turn it into a liquid. Unchanged nitrogen and hydrogen are recycled.

Q1) The Haber process is shown below and you will notice it is a reversible reaction, meaning that reactants can form products and the product can break back down into reactants.

TEMPERATURE (°C)

PRESSURE/ATMOSPHERES150 250 350

350 46.2% 57.5% 65.2%450 22.3% 31.9% 39.3%550 9.9% 15.6% 20.8%*The table above shows the final percentage yield of ammonia from the Haber process under different conditions of temperature and pressure.a) What is the product of the Haber process?

(1)b) Name two sources the reactants of the Haber process can be obtained from.

(2)c) From the table above when the reaction was conducted at 350 atmospheres and 550 °C, what was the final yield of ammonia produced?

(1)d) The table above displays the yield of ammonia produced under different conditions. Describe which conditions the Haber process should be conducted under to produce the highest yield.

(2)Q2) Urea, H2NCONH2, can be used as a fertiliser.Calculate the percentage of nitrogen in urea. Show your working clearly.

N2

H2

NH3

(3)Q3) The flow diagram shows how ammonia is converted to nitric acid.

a) Name the industrial process used to manufacture ammonia.

(1)b) Name substance X

(1)c) Ammonia and nitric acid react together to form ammonium nitrate, NH4NO3. Calculate the percentage by mass of nitrogen in ammonium nitrate. Show your working.

(3)Q4) Other nitrogen based fertilisers can be produced from ammonia. In industry, ammonia is produced in the Haber process using a catalyst.

Suggest why a catalyst may be used in an industrial process.

(1)

HOMEWORK 7 – FERTILISERS

(The Ostwald Process)

Nitric acid is made in industry by the Ostwald process. In this process, compressed air and ammonia (usually obtained from Haber process) are heated to around 800°C and then passed through layers if platinum gauze. The platinum acts as a catalyst for the reaction which takes place between the ammonia and the oxygen in the air. Ammonia (NH3) is oxidised to form

nitrogen monoxide (NO).The other product is water:ammonia + oxygen nitrogen monoxide + water

The nitrogen monoxide (NO) reacts with more oxygen (O2) to produce nitrogen dioxide (NO2), a brown gas:

nitrogen monoxide + oxygen nitrogen dioxide Next, the nitrogen dioxide is cooled, mixed with air and passed through a flow of water (H2O). During this step nitric acid (HNO3) is formed:

nitrogen dioxide + oxygen + water nitric acid The final product contains 65% nitric acid and 35% water. In order to turn the nitric acid into a nitrate salt for fertilisers, it has to be neutralised. This can be carried out by reacting it with ammonia gas from the Haber process for example: ammonia gas + nitric acid ammonium nitrate

NH3 + HNO3 NH4NO3

A platinum catalyst is used to speed up the reaction and reduce cost.

The gases are put under high pressure and a high temperature. Ammonia is obtained from the Haber process Nitric acid is used to form fertiliser salts

Q1) Potassium hydroxide reacts with nitric acid to form potassium nitrate, which can be used as a fertiliser.

KOH(aq) + HNO3(aq) KNO3(aq) + H2O(l)

a) What mass of potassium nitrate would be produced when 20g of potassium hydroxide is reacted with excess nitric acid?

(3)b) Name the type of chemical reaction taking place.

(1)c) Calculate the percentage, by mass, of potassium in potassium nitrate. Show your working clearly.

(3)Q2) Ammonia can be used to produce nitrogen dioxide as shown:

a) Name catalyst Y.

(1)

b) The nitrogen dioxide from above is then cooled, mixed with air and passed through a flow of water (H2O). What would be produced from this further reaction?

(1)c) What name is given to the full reaction to produce the product named in Q2b)?

(1)3) Calculate the percentage by mass of nitrogen in each of the following compounds which are used as fertilisers.a) sodium nitrate

(3)b) calcium nitrate

(3)c) ammonium sulphate

(3)d) ammonium nitrate

(3)HOMEWORK 8 – NUCLEAR CHEMISTRY

(Types of radiation and nuclear equations) Radioactivity

In 1896, Becquerel found that compounds of uranium emit an invisible radiation which will penetrate opaque materials and fog photographic plates. The phenomenon became known as radioactivity. Compounds of thorium behave in a similar fashion, as do natural isotopes of some other elements and artificial isotopes of most elements. The radiation was found to be affected by a magnetic or electric field as shown:

Marie Curie was a Polish-born physicist and chemist and one of the most famous scientists of her time. Together with her husband Pierre, she was awarded the Nobel Prize in 1903, and she went on to win another in 1911. Marie Sklodowska was born in Warsaw on 7 November 1867, the daughter of a teacher. In 1891, she went to Paris to study physics and mathematics at the Sorbonne where she met

Pierre Curie, professor of the School of Physics. They were married in 1895. The Curies worked together investigating radioactivity, building on the work of the German physicist Roentgen and the French physicist Becquerel. In July 1898, the Curies announced the discovery of a new chemical element, polonium. At the end of the year, they announced the discovery of another, radium. The Curies, along with Becquerel, were awarded the Nobel Prize for Physics in 1903. She received a second Nobel Prize, for Chemistry, in 1911. The Curie’s research was crucial in the development of x-rays in surgery. During World War One Curie helped to equip ambulances with x-ray equipment, which she herself drove to the front lines. The International Red Cross made her head of its radiological service and she held training courses for medical orderlies and doctors in the new techniques.

Alpha, Beta and Gamma radiation Alpha decay

An alpha particle is a charged particle consisting of two protons and two neutrons emitted (given out) by some radioisotopes. Identical to a helium nucleus and represented as

Example: Uranium 92U238 undergoes alpha decay; write a nuclear equation for this:

Beta decay A beta particle is a charged particle consisting of a single electron

emitted by some radioisotopes. Represented as

Example: Radioactive Carbon-14 undergoes beta decay; write a nuclear equation for this:

Gamma radiation is high frequency, and high energy, electromagnetic radiation emitted by radioactive substances.

Nuclear Properties

Q1) Alpha, beta and gamma radiation is passed from a source through an electric field. The gamma radiation passes directly though, unaffected by the charged plates.

Draw lines on the diagram to show what effect you would expect the charged plates would have on alpha and beta particles. Remember to label each of your lines.

(2)Q2) The element uranium has unstable atoms. These atoms give out radiation and a new element is formed.

a) Complete the table to show the number of each type of particle in

(1)b) Radon is another element which gives out radiation.

Complete the nuclide notation for element x formed after alpha decay.

(1)Q3) The table below gives information about three types of radiation emitted from radioactive elements.

a) Give values for:ABCD

(4)Q4) Complete the following equations:a)

(1)b)

(1)Q5) Which particle will be formed when an atom of 83Bi212 emits an alpha particle?

A) 82Pb207 B) 81Tl208 C) 80Hg209 D) 79Au210

(1)

HOMEWORK 9 – NUCLEAR CHEMISTRY

(Nuclear equations and half-life)

Q1) Technetium-99m is used in medicine to detect damage to heart tissue. It is a gamma-emitting radioisotope and is injected into the body. a) The half-life of technetium-99m is 6 hours.

How much of a 2g sample of technetium—99m would be left after 12 hours?

(2)b) Suggest one reason why technetium-99m can be used safely in this way

(1)c) Technetium-99m is formed when molybdenum-99 decays. The decay equation is:

Identify X: (1)

Q2) The half-life of the isotope 210Pb is 22 years. What fraction of the original sample will remain after 44 years?

A) B) C) D)(1)

Q3) Uranium is a silvery white metallic element that is radioactive because all its isotopes are unstable. Uranium decays by alpha emission. a) What is meant by the term isotope?

(1)b) Write a balanced nuclear equation for the alpha decay of 92U238.

(1)c) Uranium-238 has a half-life of 4.5 billion years. What is meant by the term half-life?

(1)Q4) Tritium, 1H3, is an isotope of hydrogen. It is formed in the upper atmosphere when hydrogen atoms capture neurons from cosmic rays. The tritium atoms then decay by beta-emission.

1H3 + a) Complete the nuclear equation above for the beta-decay of tritium atoms. (1)b) The concentration of tritium atoms in fallen rainwater is found to decrease over time. The age of any product made with water can be estimated by measuring the concentration of tritium atoms. In a bottle of wine, the concentration of tritium atoms was found to be 25% of the concentration found in rain. Given that the half-life of tritium is 12.3 years, how old is the wine?

(2)Q5) Smoke detectors use the alpha radiation from americium-241 to ionise the air in a small chamber. When smoke is present, the conductivity of the air is changed and a buzzer is activated. a) Write a balanced nuclear equation for the alpha decay of americium-241.

(1)b) The half-life of americium-241 is 433 years. Calculate the time taken for the activity of the sample to fall to 12.5% of its original value.

(2)c) Give two two reasons why americium-241 is a suitable radioisotope for use in an overhead smoke detector.

(2)

Q6) Radioisotopes are used in the treatment of patients suffering from cancer.

a) The isotope 27Co60 has a half-life of 5.3 years and is used to supply gamma radiation from outside the body of the patient. Give two reasons why this isotope would not be suitable for use inside the body.

(2)b) 15P32, a beta-emitting isotope with a half-life of 14 days, is used in the treatment of skin cancer.i) write the nuclear equation when 15P32 undergoes beta decay.

(1)ii) 3g of the isotope was used to treat cancer over a period of 56 days. Calculate the mass of the isotope which decayed during this time.

(2)Q7) The radioisotope, sodium-24, can be made in a nuclear reactor by bombarding element x with neutrons.

a) Identify element X and write values for a and b.

(2)b) The graph shows how the mass of a sample of sodium-24 varies with time.

i) What is the half-life of sodium-24?(1)

ii) What is the percentage of radioactive sodium-24 left on day 6? Show your working.

(2)

iii) If the temperature of the sodium-24 sample is increased, how would this affect its rate of nuclear decay?

(1)Use of isotopes to date materials

Complete a very short report highlighting how radioactive isotopes are used to date materials.

GradeHOMEWORK 10 – CHEMICAL ANALYSIS

(Methods of monitoring the environment using chemistry)

Q1) The concentration of chloride ions in water affects the ability of some plants to grow. A student investigated the concentration of chloride ions in

the water at various points along the river Tay. The concentration of chloride ions in water can be determined by reacting the chloride ions with silver ions.

A 20 cm3 water sample gave a precipitate of silver chloride with a mass of 1.435g. a) Calculate the number of moles of silver chloride, AgCl, present in this sample. Show your working clearly.

(2)b) Using your answer to part (a), calculate the concentration, in mol L-1, of chloride ions in this sample. Show your working clearly.

(2)

Q2) A metal treatment company were concerned that lead nitrate solution was leaking from their premises into the drainage system and then into a nearby river. Samples were taken from the drainage water and analysed to establish the lead content by titration with sodium iodide solution to precipitate lead(ii) iodide. The balanced equation for the precipitation reaction is:

Pb2+(aq) + 2I-(aq) Pb2+(I-)2(s)A 50 cm3 sample of drainage water produced a precipitate of 4.61g of lead(ii) iodide.a) Calculate the number of moles of lead(ii) iodide in the precipitate. Show your working clearly.

(2)b) Using your answer to part (a), calculate the concentration, in mol l-1, in the sample of drainage water. Show your working clearly.

(2)c) Suggest why sodium chloride would not be suitable to use instead of sodium iodide for this analysis.

(1)

Chemical Analysis Essay Write an essay describing and explaining the techniques available to chemists to help them monitor the environment. In your essay you should concentrate on the following sections: water analysis, soil analysis, chemical ions tests and precipitation reactions, acid base titration and flame testing.

GradeChemical Analysis

Write an essay describing and explaining the variety of methods for reducing pollution. Chemists play an important role in society by monitoring our environment to ensure that it remains healthy and safe and that pollution is talked as it arises.

Grade