O.a-n - Oceans | O1-5 |
O.Q Exam questions from past papers
● Ionic bonds and hydrogen bonds
are broken (2)
● Ion-dipole bonds formed (1)
Explain why many ionic substances are ● Bonds made are stronger than
soluble in water,naming the bonds which bonds broken -> exothermic reaction
are made and broken (4) (1)
Mark Schemes do not allow ionic dipole
● Measure water using measuring
cylinder (1)
● Use a polystyrene cup (1)
● Measure initial temperature (1)
● Then add solid and measure final
temp when temperature change
Describe the practical details of how a becomes constant (1)
student would carry out to find the enthalpy
change of solution of KNO3(s) from having
150cm3 of water and 10.1g of KNO3(s) (4)
Describe in full a suitable procedure and
indicate how the result would be
calculated?
Choice of acid concentration
● Calculates conc of Sr(OH)2(aq) = 0.08
● Use of reaction mole ratio 2:1 to
approximate concentration of acid
used (approx 0.15 - 0.2 mol dm-3)
Practical details
● Pipette 20/25cm3 Sr(OH)2 in a
suitable flask
● Add indicator; (details not required)
, ● Place acid in burette
● Titrate until colour change (details
not required)
● Repeat until concordant titres
obtained
Relevant fine detail
● Rinses pipette and burette with
solution to be delivered
● Performs a rough titration
● Add dropwise near to end point
Final calculation
● Calculates average volume used
from concordant titres
● Use of equation of mole ratio
● Gives example of suitable
relationship to calculate actual
concentration eg use of c=n/v
Explain how the solubility of Sr(OH)2 in
aqueous NaOH at 0 degrees compares with
3.4x10-2 moldm-3 [Compared to dissolving in
water]
Ksp = [Na+][OH-]
● Larger concentration of OH-
● Concentration of Sr2+ reduces in
order for Ksp to remain constant and
solubility is lower
● On right side there are more
Give two reasons why an increase in
particles
entropy might have been expected?
● A gas is on the right side which has
more entropy than liquids
O.Q Exam questions from past papers
● Ionic bonds and hydrogen bonds
are broken (2)
● Ion-dipole bonds formed (1)
Explain why many ionic substances are ● Bonds made are stronger than
soluble in water,naming the bonds which bonds broken -> exothermic reaction
are made and broken (4) (1)
Mark Schemes do not allow ionic dipole
● Measure water using measuring
cylinder (1)
● Use a polystyrene cup (1)
● Measure initial temperature (1)
● Then add solid and measure final
temp when temperature change
Describe the practical details of how a becomes constant (1)
student would carry out to find the enthalpy
change of solution of KNO3(s) from having
150cm3 of water and 10.1g of KNO3(s) (4)
Describe in full a suitable procedure and
indicate how the result would be
calculated?
Choice of acid concentration
● Calculates conc of Sr(OH)2(aq) = 0.08
● Use of reaction mole ratio 2:1 to
approximate concentration of acid
used (approx 0.15 - 0.2 mol dm-3)
Practical details
● Pipette 20/25cm3 Sr(OH)2 in a
suitable flask
● Add indicator; (details not required)
, ● Place acid in burette
● Titrate until colour change (details
not required)
● Repeat until concordant titres
obtained
Relevant fine detail
● Rinses pipette and burette with
solution to be delivered
● Performs a rough titration
● Add dropwise near to end point
Final calculation
● Calculates average volume used
from concordant titres
● Use of equation of mole ratio
● Gives example of suitable
relationship to calculate actual
concentration eg use of c=n/v
Explain how the solubility of Sr(OH)2 in
aqueous NaOH at 0 degrees compares with
3.4x10-2 moldm-3 [Compared to dissolving in
water]
Ksp = [Na+][OH-]
● Larger concentration of OH-
● Concentration of Sr2+ reduces in
order for Ksp to remain constant and
solubility is lower
● On right side there are more
Give two reasons why an increase in
particles
entropy might have been expected?
● A gas is on the right side which has
more entropy than liquids
