Chemstry Paper 1

• • regular lattice arrangement
  • close together


  solid( arrangement of particles)
• • strong force of attraction between particles
  • definite volume
  • definite shape
  • Not much energy

  properties of solid
• • some force of attraction between particles
  • don't have a definite shape
  • definite volume


  properties of liquid
• The stronger the intermolecular forces, the more likely it is to be a solid at room temperature.
• mixture


  if the substance has a range of boiling, melting point the substance is a
• • draw a line near the bottom of the paper
  • put a spot of mixture to be separated on the line
  • put some solvent into beaker and dip bottom of paper into it
  • put a watch glass on top of the beaker to stop any solvent from evaporating away
  • the solvent will start to move up the paper
  • different chemicals in the sample will separate out
  • remove the chromatogram from the beaker
  • mark the distance the solvent has moved in pencil

  paper chromatography practical
• producing pure water from sea water


  desalination
• • filtration- using a wire mesh to screen out large twigs, gravel
  • sedimentation- iron sulfate is added to the water, which particles clump together and settle at the bottom
  • chlorination- chlorine gas is bubbled through to kill micro-organism


  how to purify water
• what is relative atomic mass

  it is the mean mass of an atom of an element compared to 1/12 of the mass of an atom of carbon-12
• how did Mendeleev arrange elements in the periodic table

  
  

  arranged them in order of increasing relative atomic masses

  elements with similar properties were put in group

  switched the position of some element

  left gaps for undiscovered elements
• explain why ionic compounds have high melting and boiling point

  due to strong electrostatic force of attraction between ions, large amount of energy is needed to overcome this attraction
• properties of giant covalent structure

  • high melting and boiling point
  • don't conduct electricity
  • insoluble in water
• describe structure of ionic compounds

  • lattice structure
  • regular arrangement of particles
  • ions held together by strong electrostatic force
• properties of fullerenes

  • low melting point
  • spherical
  • strong covalent bond
  • slippery
• acids produce what ions in aqueous solution

  alkalis produce what ions in aqueous solution

  
  

  Acids produce H + ions

  Alkalis produce OH- ions
• what is ph scale

  it is a scale that measures the acidity and alkalinity of a solution
• • ph 7 is neutral
  • <ph 7 is acidic
  • >ph7 is alkaline
• Phenolphthalein

  Alkaline = pink

  Acidic = colourless
• Methyl orange

  Alkaline = yellow

  Acidic = red
• litmus solution

  ■ Alkaline = blue

  ■ Acidic = red
• explain the link between ph and the concentration of ions in acids and alkalis

  the higher the concentration of hydrogen ions in an acidic solution, the lower the pH

  the higher the concentration of hydroxide ions in an alkaline solution, the higher the pH
• describe the relationship between hydrogen ion concentration and Ph

  as hydrogen ion concentration in a solution increases by a factor of 10, the pH of the solution decreases by 1 and vice versa
• dilute- a low concentration of a solute in a solution

  concentrated- a high concentration of solute in a solution
• weak acids- an acidic solute that does not dissociate completely into ions when it dissolves
• strong acids- an acidic solute that dissolves completely into ions when it dissolves
• a base is any substance that reacts with an acid to form a salt and water only
• Test for hydrogen:

  apply a lighted splint, it makes a squeaky pop noise
• Test for carbon dioxide:

  Bubble the gas through the limewater and it will turn milky
• general reaction of acids

  acid + metal → salt + hydrogen gas (H2 )

  acid + metal oxide → salt + water

  acid + metal hydroxide → salt + water

  acid + metal carbonate → salt + water + carbon dioxide (CO2 )
• a neutralisation reaction is a reaction between an acid and a base
• Explain why, if soluble salts are prepared from an acid and an insoluble reactant: excess of the reactant is added

  this is to ensure the volume of acid reacts completely
• Explain why, if soluble salts are prepared from an acid and an insoluble reactant: the excess reactant is removed

  so that you are left with just a salt and water
• Explain why, if soluble salts are prepared from an acid and an insoluble reactant: the solution remaining is only salt and water

  all of your acid has fully reacted and you have filtered off your other reactants
• Describe the method used to prepare a pure, dry sample of an insoluble salt

  1. mix the two solutions needed to form the salt
  2. filter the mixture using filter paper, which the insoluble salt will be left on
  3. wash the salt using distilled water
  4. leave the salt to dry on filter paper
• for any neutralisation reaction with an acid and an alkali the ionic equation is: H + (aq) + OH- (aq) -> H2O(l)
• Describe how to carry out an acid-alkali titration, using burette, pipette and a suitable indicator, to prepare a pure, dry salt

  *measure out a set amount of acids into a conical flask, using a pipette

  *add a few drops of indicators( phenolphthalein, methyl orange)

  *add alkali to acid slowly, using a burette, until the end-point is reached

  *to prepare a pure, dry salt – you warm the salt solution to evaporate the water

  *then leave to crystallise

  *filter off the solid and dry it
• Explain why, if soluble salts are prepared from an acid and a soluble reactant: titration must be used

  both reactants are liquids/soluble, so if you have an excess of one you would not be able to easily remove it from your mixture of products, this means you need to measure the exact amount of volumes that react, which is easily done using a titration
• Describe an experiment to determine the empirical formula of a simple compound such as magnesium oxide

  • weigh some pure magnesium

  ● Heat magnesium to burning in a crucible to form magnesium oxide

  ● weigh the mass of the magnesium oxide
• empirical formula is the simplest whole number ratio of atoms in a compound
• Relative formula mass (Mr) of a compound is sum of the relative atomic masses of the atoms