quantitive chemistry

• A mole in chemistry is a unit of measurement that represents the amount of a substance. It is equal to 6.022 x 10^23 particles.
• the law of conservation of mass is where the total mass of reactants is equal to the total mass of products
• a metal salt + hydrogen is created when a metal reacts with an acid
• during hydration steam is reacted with ethane to give ethanol
• 2 ways ethanol is produced:

  • fermentation
  • hydration
• to calculate atom economy:

  sum of formula mass of desired product

  --------------------------------------

  relative formula mass of all reactants

  x100
• Concentration is typically expressed as the amount of solute dissolved in a given amount of solvent or solution.
• The formula for calculating the concentration of a solution is: concentration = mol / vol.
• a titration is a method to find how much acid is needed to neutralise an alkali
• relative formula mass is the sum of all atomic masses in a substance
• electrodes are made out of carbon
• in a redox reaction, both oxidation and reduction take place
• in electrolysis:

  the positive ions=cations

  the negative ions=anions
• in electrolysis:

  the positive electrodes=anodes

  the negative electrodes=cathodes
• electrolysis is the use of an electrical current to break down compounds containing ions into their elements
• a change of 1 unit of pH indicates the concentration of H+ ions has decreased by 10
• a strong acid is where the H+ ions are fully ionised in water
• litmus paper changes:

  red=acid

  blue=alkali
• pH is measured by:

  • universal indicator
  • pH probe
• the pH scale is a measure of the acidity or alkalinity of a substance
• a displacement reaction is when a more reactive metal will displace a less reactive metal from its salt
• reactivity is how easily a substance loses electrons
• reduction is the:

  • loss of oxygen
  • gain of electrons
• oxidation is the:

  • gain of oxygen
  • loss of electrons
• hydration is better than fermentation as hydration has an atom economy of 100%
• scientists choose pathways with high atom economies as:

  • more money/profit is made
  • less wasted materials
  • sustainable development
• atom economy is the measure of the amount of reactants that end up as useful product
• percentage yield is calculated by:

  actual yield

  ----------- x100

  theoretical yield
• 2 indicators used in titrations:

  • methyl orange
  • phenolphthalein
• the neutralisation equation is

  H+ + OH- = H20
• a limiting reactant is when 1 reactant is used up so it stops the reaction going any further
• the calculation for moles:

  mass(g)

  ------------

  atomic/formula mass (Mr)(g/mol)
• reactions have a change in mass when:

  • they're carried out in a non closed system
  • they involve a gas that can escape or enter the system
• mass is conserved in a reaction as no atoms are lost or made