Chemistry

• concentration = no. of moles divide by volume
• why do you not get 100% yield?

  not all reactants react to make a product, might be side reactions, you lose products when separating reaction mixture
• acids plus bases neutralise each other
• acids form H+ ions in water
• what is a base?

  any substance that will react with an acid to form a salt
• acid + base - salt + water
• universal indicator made from a mixture of different indicators colour gradually changes and can be variety of colours - estimate pH
• in titrations you want sudden colour change - so use a single indicator
• in titrations you need to use a burette
• what is the indicator that goes colourless in acids and pink in alkalis?

  phenolphthalein
• what does phenophthalein go in acids?

  colourless
• what does phenolphthalein go in alkalis?

  pink
• what indicator goes red in acids,and blue in alkalis?

  litmus
• what colour does litmus go in acids?

  red
• what colour does litmus go in alkalis?

  blue
• what indicator goes red in acids and yellow in alkalis?

  methyl orange
• what colour does methyl go in acids?

  red
• what colour does alkalis go in methyl orange?

  yellow
• acids produce protons in water
• acids ionise in aqueous solutions and produce hydrogen ions H+
• strong acids ionise completely in water - acid particles dissociate to release H+ ions
• weak acids do not fully ionise in solution, only small proportion of acid particles dissociate to release H+ ions
• ionisation of a weak acid is a reversible reaction
• equilibrium lies well to the left in ionisation of a weak acid
• pH is measure of concentration of H+ ions in the solution
• every decrease of 1 on pH has increase by factor 10 on concentration
• if you work the difference between the pH's and that 10 *
• strong acids are not same as concentration
• acid strength tells you what proportion of acid molecules ionise in water
• concentration measures how much acid there is in a certain volume of water
• acid + metal oxide - salt + water
• acid + metal hydroxide - salt + water
• acid + metal carbonate - salt + water + carbon dioxide
• acid + metal - salt + hydrogen
• metal + water - metal hydroxide + hydrogen
• speed of reaction is indicated by the rate at which bubbles of hydrogen are given off
• oxidation is the gain of oxygen
• reduction is loss of oxygen
• metals higher than carbon in reactivity series have to be extracted using electrolysis
• metals below carbon in reactivity series can be extracted from their ores by reduction with carbon