AS Chemistry 2020 Paper 2 question
with answers
ammonia nucleophilic substitution - -
-An experiment is done to determine the enthalpy of combustion of a fuel
using a calorimeter containing water. b = mass of fuel burned / g w = mass
of water heated / g ΔT = temperature rise of water / K Mr = relative
molecular mass of fuel c = specific heat capacity of water / J K-1 g-1 Which
expression gives the enthalpy of combustion (in J mol-1 ), assuming there is
no heat loss? - - -c w ΔT Mr/ b
-Define the term standard enthalpy of formation. - - The enthalpy change
when 1 mole of a compound is formed from elements with all substances in
its standard states.
-Give an equation for each propagation step in the formation of 1-
chloropropane from propane. - - CH3CH2CH3 + •Cl → •CH2CH2CH3 + HCl
M3 •CH2CH2CH3 + Cl2 → ClCH2CH2CH3 + •Cl
-In which reaction does the inorganic reagent act initially as an electrophile?
- - ethene with concentrated sulfuric acid
-State the importance of percentage yield and percentage atom economy
when choosing the method used to make a compound - - percentage yield-
idea of getting as much product as possible in the reaction
atom economy- idea of maximising the mass of reactants / atoms that ends
up in desired product
-State what you would observe if bromine water was added to
poly(chloroethene). Explain this observation. - - no reaction polymer is
saturated does not contain double bond
-Suggest why the student records the times to the nearest second and not
to the nearest 0.01 s - - Idea that it is hard to judge to the nearest 0.01
second
-Suggest, by considering the products of this reaction, why small amounts of
reactants are used in this experiment. - - to limit amount of SO2 formed
-What is the minimum volume of 0.0500 mol dm-3 aqueous bromine needed
to react completely with 0.0200 g of buta-1,3-diene? - - 14.8 cm3
with answers
ammonia nucleophilic substitution - -
-An experiment is done to determine the enthalpy of combustion of a fuel
using a calorimeter containing water. b = mass of fuel burned / g w = mass
of water heated / g ΔT = temperature rise of water / K Mr = relative
molecular mass of fuel c = specific heat capacity of water / J K-1 g-1 Which
expression gives the enthalpy of combustion (in J mol-1 ), assuming there is
no heat loss? - - -c w ΔT Mr/ b
-Define the term standard enthalpy of formation. - - The enthalpy change
when 1 mole of a compound is formed from elements with all substances in
its standard states.
-Give an equation for each propagation step in the formation of 1-
chloropropane from propane. - - CH3CH2CH3 + •Cl → •CH2CH2CH3 + HCl
M3 •CH2CH2CH3 + Cl2 → ClCH2CH2CH3 + •Cl
-In which reaction does the inorganic reagent act initially as an electrophile?
- - ethene with concentrated sulfuric acid
-State the importance of percentage yield and percentage atom economy
when choosing the method used to make a compound - - percentage yield-
idea of getting as much product as possible in the reaction
atom economy- idea of maximising the mass of reactants / atoms that ends
up in desired product
-State what you would observe if bromine water was added to
poly(chloroethene). Explain this observation. - - no reaction polymer is
saturated does not contain double bond
-Suggest why the student records the times to the nearest second and not
to the nearest 0.01 s - - Idea that it is hard to judge to the nearest 0.01
second
-Suggest, by considering the products of this reaction, why small amounts of
reactants are used in this experiment. - - to limit amount of SO2 formed
-What is the minimum volume of 0.0500 mol dm-3 aqueous bromine needed
to react completely with 0.0200 g of buta-1,3-diene? - - 14.8 cm3
