chemistry revision ap2

• aqueous symbol is?

  aq
• “mass has not been conserved in a reaction because the mass decreased” why are they wrong?

  because the law of conservation of mass states that atoms are not destroyed they are merely rearranged. the flask was also open while conserving the mass meaning the gas produed has escaped the flask.
• exothermic reactions transfer energy??

  to the surroundings
• endothermic reactions transfer energy??

  from the surrounding
• in a endothermic profile is the reactants or products higher?

  the products are higher then the reactants
• in a exothermic profile is the reactants or products higher?

  the reactants
• percentage yield = ?

  actual yield / theoretical yield x100
• reasons why percentage yield is not achieved?

  • reactants may be impure
  • reactants may be lost during separation
  • reactants may have been lost when transferred to another flask
  • the reactants reacted differently that expected in the reaction
• factors that affect chemical reactions

  • temperature
  • surface area
  • concentration
  • catalyst
• how does surface area increase rate of reaction?

  because there will be more reacting particles exposed which means there will be more frequent successful collisions increasing the rate of reaction
• how does temperature increase rate of reaction?

  the higher the temperature the more kinetic store energy, which means more moving and reacting particles

  activated, so there will be more frequent successful collisions increasing the rate of reaction.
• how does concentration increase the rate of reaction?


  higher the concentration, the more frequent successful collisions because there are more particles close together in the same amount of space which will increase the reaction meaning more frequent successful collisions
• exorthermic reactions break or form bonds?

  form
• endothermic reaction break or form bonds?

  break
• what do catalyst’s do?


  decrease the activation energy by speeding up the reactions
• what reaction is this and label it

  exothermic reaction,

  a= energy

  b = reaction progress

  c = reactants

  d = products

  e= energy change

  
• what reaction is this and label the parts

  endothermic reaction

  a = energy

  b= reactants

  c = energy change

  d = products

  e = reaction progress