Markscheme points Flashcards
(19 cards)
How to make salt dissolve faster
stir solution or heat
why is catalytic cracking important
alkenes are needed to make polymers and short chain alkanes and alkenes are in higher demand
why is sulfur a problem
when a fuel is burnt, reacts with oxygen, sulfur dioxide dissolves in water, sulfuric acid made and acid rain
colour of compound formed between iron and oxygen
brown
why iron powder needs to be wet for reaction between iron and oxygen
water causes rust
what does bromine reaction with ethane involve breaking of
C-H bond
what does bromine reaction with ethene involve breaking of
carbon carbon double bond
why is value of x lower than calculated value
not heated for long enough, not all water removed
what do the layers do in graphite
layers slide over each other, weak forces between layers
in reaction of red oxide heated to form yellow oxide and oxygen, how can we make sure all the red oxide has reacted
Heat again and repeat until constant mass obtained
test for ammonium ions
add sodium hydroxide, damp red litmus paper turns blue
how does plastic prevent iron from rusting
prevents oxygen and water reaching iron layer and acts a barrier
increasing pressure effect on rate of reaction
faster as particles are closer together and more particles in a smaller volume, more successful collision per unit time as increase collision frequency
test for sulfate ions
add HCl, barium chloride, white precipitate forms
advantage of using polystyrene cup
insulator that reduces heat loss to surroundings, temperature decrease of reaction will be closer to true value
reason for anomalous result in investigation of temperature change
forgot to stir, recorded temp before adding reactant, didn’t add the correct mass
sodium carbonate added to HCl is what type of reaction if there’s a temperature decrease in results?
endothermic - takes in heat from surroundings
why mass of CO2 produced is less than calculated mass in reaction between sodium carbonate and HCl
some CO2 dissolves in acid, Na2CO3 is impure
small piece of calcium added to dilute sulfuric acid, calcium sulfate which is insoluble in water formed, why does the reaction stop after a short time even though the beaker still contains calcium and dilute sulfuric acid
calcium sulfate forms a layer/coating around calcium metal
