AQA Chemistry 3

Revision cards for C3

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Acids and Alkalis

Acids

  • When they dissolve into water they form H+ ions.
  • Release H+ ions which are protons
  • Proton Donors
  • Stronger acid will have an increasing concentration of H+ ions and will be completely ionised. Example
    • Sulfuric Acid H2 SO4
    • Nitric Acid HNO3
    • Hydrochloric Acid HCl
  • Weak Acids are partially ionised or not fully dissociated.
    • Citric Acid
    • Ethanoic Acid
    • Carbonic Acid

Alkalis

  • When they dissolve in water they form OH- ions
  • Accept H+ ions which are protons
  • Proton Acceptors
  • Stronger Alkalis will have an increasing concentration of OH- ions and will be completely ionised. Examples :
    • Potassium Hydroxide KOH
    • Sodium Hydroxide NaOH
  • Weak Alkalis will be partially ionised or not fully dissociated
    • Ammonia Solution
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Titration

Titration

  • They are used to find out concentrations.
  • They allow you to find teh exact amount of acid needed to neutralise an amount of alkali.
  • The END POINT is the point in the acid and the alkali have neutralised completely.
    • Strong Alkali + Strong Acid = Any indicator
    • Strong Alkali + Weak Acid = Phenophthalein
    • Weak Alkali + Strong Acid =  Methyl Orange
  • Measure out 25 cm* of Acid or alkali in a pipette ( used to measure out a fixed volume of solution) and empty it out in a concial flask
  • Put the suitable Indicator in the Flask
  • Put the other reactant (acid/alkali) in the burette ( used to measure the volume of solution added)
  • Drip the liquid from the burette slowly as you are nearing a colour change
  • record the burette volume when the colour change occurs (END POINT)
  • Repeat it three time and get average
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Energy

Exothermic Reaction -

  • Gives out heat ... X = Exit
  • Temperature increases
  • More bonds made than bonds broken
  • More chemical energy in the reactants than the products as energy is released
  • Burning 
  • Neutralisation reaction between Acid and Alkali
  • Reaction between calcium oxide and water
  • 

Endothermic Reaction -

  • Takes in heat ..  En = In
  • More enerygy is in the product than in the reactants as energy has been taken in.
  • Electroylsis
  • Reaction between Ethanoic Acid and Sodium Carbonate
  • Thermal Decomposition of limestone in a blast furnace
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Water

Water Cycle

  • Evaporation
  • Condesation
  • Precicpitation

Solubility

  • the maximum amount of solute that can dissolve in a certain amount of solvent
  • Ionic compounds are soluble but covalent are insoluble
  • to increase solubility in gases ..
    • temp decrease
    • pressure incresae
  • to increase the solubility in liquids
    • temp increase
  • A saturated solution is where a solute can not dissolve even more than it has dissolved now
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Hard water

  • permenant will include
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