A level Paper 2 mistakes Flashcards
How do you work out Ea when using Arrhenius constant?
Calculate the gradient between 2 points.
Multiply by R (8.31) to get Ea in J.
Divide by 1000
In condensation polymerisation with an alcohol and carboxylic acid group, how is the water molecule formed?
The OH from the carboxylic acid combines with the H from the alcohol.
One similarity and one difference between addition polymers and condensation polymers.
In both, monomers join by covalent bonds to form polymers.
No additional products in addition. A water molecule is also formed in condensation polymerisation.
Give 3 ways in which polymers can be utilised to improve their sustainability.
Recycle
Incinerate to release energy
Use as feedstock
If a dicarboxylic acid is diluted and then 25cm3 is titrated with sodium hydroxide, what is the ratio in which they react?
base : carboxylic acid
2. : 1
Explain why amino acids are crystalline solids at room temperature.
Amino acids exist as zwitterions.
So ionic bonds form between amino acids.
Explain why the ammonia molecule and ammonium ion have different shapes and bond angles.
lone pair of electrons on ammonia repels more than bonding pairs.
Ammonia has one lone pair and 3 bonding pairs.the ammonium ion has four bond pairs
the ammonia molecule is (trigonal) pyramidal
ammonium ion is tetrahedral
the bond angle in ammonia is 107(°)
the bond angle in the ammonium ion is 109.5(°)
State how the use of anti-bumping granules gives smoother boiling.
Provides a surface for bubbles to form.
What does reforming do?
Converts straight-chain alkanes into more branched or cyclic forms.
Give 2 reasons why different amino acids have different Rf values.
Different solubility to stationary phase
Different solubility in mobile phase
State how granules prevent bumping.
They provide a surface for bubbles to form.
Devise an experiment that would enable the rates of hydrolysis of halogenoalkanes to be compared.
(M1) use of ethanol (as a solvent) (1)
(M2) use of silver nitrate (solution) (1)
(M3) equal amounts used of each halogenoalkane (1)
(M4) measure the time taken for precipitate to form (1)
(M5) use a water bath (to control a raised temperature)
(1)
Give one advantage and one disadvantage of the disposal of polystyrene by incineration.
Advantage: Release of energy
Disadvantage: Releases toxic fumes
Sate why the order of reaction with respect to iodide ions cannot be 5 even though 5 moles of iodide ions react in the equation.
The chance of 5 ions colliding in the rate determining step is negligible.
In air bags, sodium and potassium oxides are formed and they then react with silicon dioxide.
State the type of reaction taking place and why this is necessary.
Neutralisation
Sodium and potassium oxides are corrosive.
Salts formed are inert.
One version of an iodine clock reaction is where hydrogen peroxide reacts with potassium iodide to produce iodine.
Explain the purpose of starch in the reaction mixture.
Acts as an indicator.
Time taken for blue-black complex to form can be used to calculate rate.
