C5 - How Much?

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Moles and Emprical Formulae & Electrolysis - Quest

Moles and empirical formulae

  • What is the molar mass of this acid: Ch3C(CH)2COOH ?
  • How much carbon dioxide is made when 440g propane, C3H8 is burned?
  • What is the empirical formula for hexane, C6H14?
  • 110g of sulfuric acid contains 2.04%H, 32.65% S and 65.31% O. Work out the empirical formula of sulfuric acid.


  • Which type of ions move towards the cathode during electrolysis?
  • Write down two half equations that represent electrolysis of Pbl2
  • Write down two quantities that change the amount produced at an electrode.
  • How much charge is transferred by a current or 0.2A for 3 hours?
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Moles and Emprical Formulae & Electrolysis - Answe

Moles and Empirical Formulae

  • 90
  • 1320g
  • C3 H7
  • H2 SO4


  • Negative ions - cations.
  • Pb2+ + 2e = Pb and 2l - 2e = l2
  • Current and time
  • 2160
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Quantitive analysis & Ionic Equations - Questions

Quantative analysis

  • What is a solute?
  • How many grams of sodium are there in 25g of salt?
  • You have a 10cm3 of a solution. You want to make it 10 times as dilute. How much water do you add?
  • There is 1 mole of salt in 2dm3 of water. What is the concentration of the solution in mol/dm3?

Ionic Equations

  • Write a word equation for the reaction of silver nitrate and sodium iodide.
  • Why are sodium ions and  nitrate ions after spectator ions?
  • Why do you wash a precipitate in distilled water when making a dry sample?
  • Write an ionic equation for the reaction of silver nitrate and sodium bromide.
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Quantitive analysis & Ionic Equations - Answers

Quantative analysis

  • A substance that dissolves in a liquid.
  • 15g.
  • 90cm3
  • 0.5

Ionic Equations

  • Silver nitrate + sodium iodide = silver iodide + sodium nitrate
  • If the solution used to make the precipitate was potassium nitrate instead of sodium nitrate the same precipitate would occur as sodium potassium and nitrate ions remain in solution.
  • To remove traces of the solution filtered with the precipitate.
  • Ag+ + Br- = AgBr
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Titrations & Gas volumes - Questions


  • Alakli is slowly added to acid. How does the Ph change?
  • If number of moles - concentration x volume in dm3, write down the relationship for concentration.
  • Why are titration carried out several times before a volume is decided?
  • 23.6 cm3 os a solution of 0.12 mol/dm3 hydrochloric acid react with 25.0 cm3 of sodium hydroxide colution. What is the concentration of the sodium hydroxide solution?

Gas Volumes

  • A reaction gave off 96cm3 of sulfur dioxide. How may moles were made?
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Titrations & Gas volumes - Answers


  • It increases
  • Concentration = number of moles / volume
  • To increase the reliability
  • 0.113 mol/dm3

Gas volumes

  • 17cm3
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Equilibria & Strong and weak acids - Questions


  • At equilibrium, the reaction A+B=C+D has 1 mole of A and B and 3 moles of C and D. Where is the position of the equilibrium?
  • What happens to the equilibrium in the reaction of gases: N2+3H2=2NH3 is the pressure is increased?
  • What are the conditions used in the Contact Process?
  • Why is it called a compromise temperature in the Contact Process?

Strong and weak acids

  • Strong acids break into their ions completely if put into water. What happens to weak acids when they are put into water?
  • Explain why ethanoic acid is a weak acid.
  • One ion makes a solution into an acid. Which one?
  • Explain why strong acids react faster than weak acids.
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Equilibria & Strong and weak acids - Answers


  • To the right
  • Moces to the right
  • 450 Oc, atmospheric pressure, catalyst of vanadium pentoxide. V2O5.
  • High temperature reduce the yielf of the reaction but the rate would be too low at low temperatures, so a somprimise is found, 450 Oc.

Strong and Weak acids

  • Not all molecules seperate ions.
  • The ionisation of ethanoic acid in water is not compelte. It is a reversible reaction where the position of equilibrium lies to the left.
  • H+
  • In strong acids the concentration of H+ is higher, so collision frequency is greater.
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this is really good!!

Matthew Smolicz


Thanks :)

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