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Flashcards

Chemistry 3

mollieroselewis Chemistry GCSE English 47 cards

Cards in this deck (47)

  1. 1What is meant by 'Qualitative analysis'?Investigation of the types of substance present in a sample
  2. 2What is meant be 'Quantitative analysis'?Measurement of the amount of each substance present in a sample
  3. 3How do you carry out tests for metal cations using sodium hydroxide solution?1) Dissolve the sample in water.
    2) Add a few drops of sodium hydroxide solution.
    3) many meta cations in solution form insoluble precipitates when this is done.
  4. 4What colour hydroxide precipitates do these metal cations form 1) aluminium 2) calcium 3) copper 4) iron (ii) 5) iron (iii)1) aluminium = white
    2) calcium = white
    3) copper = pale blue
    4) iron (ii) = green
    5) iron (iii) = brown
  5. 5Aluminium ions and calcium ions both form a white hydroxide precipitate. How can you tell them apart?Aluminium hydroxide precipitate re-dissolves to form a colourless solution when excess sodium hydroxide solution is added, whereas calcium hydroxide precipitate does not re-dissolve.
  6. 6Why do chemists working in the water industry test the purity of drinking water?They need to be sure that the water does not contain any harmful dissolved substances.
  7. 7What is the test for halide ions?1) Add a few drop of dilute nitric acid to the sample.
    2) Then add a few drops of silver nitrate solution.
    3) A different colour precipitate forms depending on the halide ion present.
    - Chloride = white
    - Bromide = cream
    - Iodide = yellow
  8. 8Why is drinking water not pure?Because it contains dissolved substances. Some of these are deliberately added to tap water. It is important to make sure that the amount of each dissolved substance found in drinking water is safe.
  9. 9What dissolved substances are deliberately added to tap water and why?1) Chlorine is added to kill harmful microorganisms.
    2) Aluminium sulphate is added to remove small solid particles.
  10. 10Why do Analytical Chemists test blood samples?To identify why their patients are ill. For example, high levels of aluminium in the blood are linked with Alzheimer's disease.
  11. 11Describe the test to see if a water sample contains sulphate ions.1) Add a small volume of water to a test tube.
    2) Add a few drops of hydrochloric acid.
    3) Then add a few drops of barium chloride solution.
    4) If a white precipitate forms, the water contains sulphate ions.
  12. 12Describe the test for carbonate ions in a water sample.1) Add dilute hydrochloric acid to the sample.
    2) If the sample contains carbonate ions, you will briefly see bubbles. (This gas is carbon dioxide. It will turn limewater milky)
  13. 13What is hard water?water from river, lakes and reservoirs that has run over rocks containing calcium or magnesium ions. Some of these ions dissolve in the water forming hard water.
  14. 14What are the problems with hard water?1) It does not easily form a lather with soap.
    2) The calcium and magnesium ions react with soap, forming a precipitate called scum. ( This causes the soap to be wasted.)
  15. 15What is a solute?The substance in a solution that has dissolved.
  16. 16What is a solvent?The liquid in a solution that dissolves the solvent.
  17. 17What is the concentration of a solute measured in?g dm-3
  18. 18How do you calculate the concentration of a solute?Concentration (g dm-3) = Mass of solute (g) / Volume of solution (dm-3)
  19. 19What is temporary hardness?When the water contains dissolved calcium hydrogencarbnate (Ca(HCO3)2)
  20. 20How can you remove temporary hardness?By boiling the water. This works because calcium hydrogencarbonate breaks down when heated.
  21. 21What is the term for removing hardness from water?Softening
  22. 22What is permanent hardness?When the water contains substances such as calcium sulphate (CaSO4)
  23. 23How can you remove permanent hardness?Buy using ion exchange columns.
  24. 24How do Ion Exchange Columns remove permanent hardness from water.The column has little beads in it made from ion exchange resin. Hard water is sent through the column. As the water goes through its calcium ions are swapped for sodium ions from the resin. Sodium ions do not form scum with soap, so the water is softened.
  25. 25What is Avogadro's number?(6.02 x 10 to the 23)
    It is the number if carbon atoms in 12g of carbon.
  26. 26What is a mole?One mole of any type of particle contains this number of particles, whether they are atoms, ions or molecules.
  27. 27How do you work out the number of moles of an element?no. of mole = mass in grams / relative atomic mass
  28. 28What is the relative formula mass of a substance?The sum of all the relative atomic masses of all the atoms in the formula.
  29. 29How do you work out the number of moles of a compound?no. of moles = mass in grams/ relative formula mass
  30. 30What is the concentration of a solute in a solution measured in?1) g dm-3
    2) moles dm-3
  31. 31How can you calculate the mass of a given number of moles of a substance is you know its relative atomic mass or relative formula mass?1) Mass in grams = relative atomic mass x number of moles
    2) Mass in grams = relative formula mass x number of moles.
  32. 32How can you calculate the concentration of a solute in a solution?Concentration (mol dm-3) = moles of a solute (mol) / volume of a solute (dm3)
  33. 33Dow many cm3 are in one dm3?1000
  34. 34How do you convert from g dm-3 to mol dm-3?concentration/ relative formula mass
  35. 35How do you convert mol dm-3 to g dm-3?concentration x relative formula mass
  36. 36What are the three main steps needed to make a soluble salt from a soluble base?1) Use an acid-base titration to find the exact volume of the soluble base that reacts with the acid.
    2) Mix the acid and soluble base in the correct proportions, producing a solution of the salt and water.
    3) Warm the salt solution to evaporate the water - this will leave crystals of the salt behind.
  37. 37What are the three main steps needed to make a soluble salt from an insoluble base?1) Add and excess of insoluble base to the acid.
    2) Remove excess insoluble base by filtration.
    3) Evaporate to produce crystals of the salt.
  38. 38What is the electrolysis?The decomposition of a compound using a direct current through water
  39. 39What are cationsPositive ions
  40. 40What are anions?negative ions
  41. 41What is a cathode?A negative electrode
  42. 42What is an anode?a positive electrode
  43. 43What are some uses of sodium?1) Street lamps, beacuse A bright yellow light s given out when an electric current is passed through sodium vapour in the lamp.
    2) A Coolant in nuclear power stations, because Liquid sodium has a high 'street capacity' (it takes a lot of heat energy to raise its temperature)
  44. 44In electrolysis, at which electrode does reduction take place?The Cathode
  45. 45In electrolysis, at which electrode does oxidation take place?The Anode
  46. 46What are the 3 products when an aqueous solution of sodium chloride is electrolysed?1) Hydrogen
    2) Chlorine
    3) Sodium hydroxide solution
  47. 47—

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GCSE Chemistry Flashcards on Chemistry 3, created by mollieroselewis on 11/05/2016.
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