F334 Past paper questions

Explain what is meant by crystaline

PPA is more crystalline than nylon-6. This gives PPA a greater Tm than nylon-6.
Explain the greater Tm in terms of intermolecular bonding involved (3)

Suggest why scientists once thought that proteins were more likely to transmit genetic data (2)

What is meant by the secondary and tertiary structure of an enzyme (2)

Name the type of polymerisation reaction is needed to form nylon-6 (1)

Name a process by which nylon-6 can be made more crysalline

Give two successful outcomes of clinical trials that would be necessary before a drug can be classed as an effective drug (2)

Suggest why stereoisomers would be expected to have different activities in the body (2)

What properties should a solvent have to achieve efficient recrystallisation (2)

Explain why resveratrol (contains 3 phenol groups) reacts with NaOH (aq) and suggest why the products are soluble in water. (4)

The rates of reaction are measured when the amounts of reactants used up are small in comparison to the total quantities of reactant present.
Explain why it is necessary to do this. (2)

Explain the meaning of enantiomers (2)

Explain how cross links in polymers are formed

Name a suitable reagent for converting a carboxylic acid into a carboxylate ion

A cross-linked polymer does not dissolve when water is added, a polymer without cross-links eventually dissolves when enough water is added.
Suggest and explain a reason for this difference in properties. (2)

The voltage of a battery measured with a high resistance voltmeter is less than the value of the batteries Ecell value.
Suggest why

Suggest and explain a reason why it is much easier to recycle super absorbent polymers than polymers from a mixture of used packaging,

What happens why sodium carbonate is added to a carboxylic acid

Why is it important that reactions have a high atom economy (2)

What are the conditions for an electrochemical cell

State the colour of Cu2+ ions in water and explain why the solution has this colour. (2)

What is the colour of the [Fe(H2O)6]3+ ion in water?

When conc HCl (aq) is added to a solution of Cu2+ ions, what type of reaction occurs, and give the formula of product containing the copper (2)

Describe how colorimetry is used to determine the concentration of Cu2+ ions in an aqueous sample

Many members of the public believe that the DNA fingerprints of the innocent should be removed from the DNA database. Others disagree with this view
Give a reason for each of the two viewpoints

Describe and explain the effect on the crystallinity of a polymer of changing the double bonds to 50% cis and 50% trans (2)

Materials made from nylon-6 can absorb moisture, but those made from neoprene cannot (no NH2 group).
Explain these observations
Describe how the effect of water absorption on the chain arrangement in nylon-6 and thus on its Tg (4)

High-resolution mass spec can be used to determine the molecular formula of a compound by measuring the mass:charge ratio of the M+ peak.
Explain how the molecular formula of a molecule can be determined from an accurate mass:charge ratio for the M+ peak in its mass spectrum

Recrystallisation removes both soluble and insoluble impurities.
Describe how a student would carry out this procedure using a suitable solvent (5)

Give three questions that clinical trials are designed to answer (3)

Explain how a student would use a colorimeter and calibration curve to determine the concentrations of 'compound B' as a purple colour faded in the titration flask.
Explain how the student would use the results to show that the reaction taking place is in first order with respect to compound B (5)

Explain why the enzyme activity is less when the pH is changed slightly from its optimum value

At low concentrations of amino acid P, the synthesis reaction is first order with respect to P and first order with respect to the enzyme. Give the rate equation for the reaction.

Rate = K [P] [enzyme]
Explain why at low concentrations of P, the reaction is first order with respect to P

Rate = K [P] [enzyme]
At high concentrations of P, the reaction is no longer in first order with respect to P
Give the new order and how it arises (2)

Give two ways that enzymes may increase the efficiency of an industrial process

One way that DNA can be damaged is by alteration in the sequence of bases.
Describe and explain how this damage could damage could result in enzymes becoming less effective for a particular reason. (6)

Give one way a polymer could be made more flexible (1)

Solutions of Potassium manganite can be standardised against a measured volume of a standard solution of sodium ethanedioate, under acidic conditions. The contents of the titration flask have to be warmed to 60degrees before starting, otherwise the reaction is too slow.
Describe how you would carry out this titration to get one result (5)

Why do you add dilute sulphuric acid in a redox titration with managanate ions?

Explain how transition metal ions such as Cu2+ are able to increase the rate of a redox reaction. (4)

What name is given to this type catalysis by aqueous transition metal ions?

Explain why copper is a transition metal

Describe a method for protecting copper from corrosion

In a titration of sodium thiosulfate and iodine. The student went past the end point and added too much sodium sulcate. What effect would this have on their answer for the concentration of iodine. (2)

Describe one difference between heating under reflux and distillation (2)

Explain in terms of structure and intermolecular bonding why a molecule that can react with both alkali and acid has such a high melting point (3)

Describe the properties of a polymer at temperatures above its Tm
Describe and explain the properties of a polymer at temperatures below its Tg
Suggest why the blended polymer has a higher Tm.

Suggest a way of removing Fe2O3 from the mixture formed after the reaction with sulphuric acid

explain the meaning f electronegativity

What makes an reaction an acid-base reaction

What makes NH2CH2CH2NH2 a bidentate ligand

Give the chemical reagent and conditions needed to break down a protein into amino acids in a lab

Explain why a protein with a tertiary structure is affected by lowering the pH
Give the groups that would be affected by lowering the pH (3)

Explain why the curve on the graph (gradually increases then decreases) for rate of reaction using enzymes rises then falls sharply (4)

Describe how thin-layer chromatography can be used to show that chemicals are present in cinnamon oil (5)

Describe what happens to vapour when it is heated under reflux and give one reason why reflux was used in this reaction

Explain why a substance produces a spectrum showing absorption peaks when interacts with IR radiation (2)

Describe what would happen to a bottle made from PET if it was heated to 300degrees in the absence of air

Explain the term zwitter ion

A chemist wanted to make phenyl methyl ethanoate. Suggest three compounds that could be used to react with the alcohol to produce the ester.

What is combinatorial chemistry

What are the 4 different types of reaction

What is a transition metal metal defined as?

Why do scandium and zinc not display the chemical properties associated with transition metals?

Why do transition metals have variable oxidation states?

Suggest why certain properties are common to transition metals, but different from the properties of s-block metals

Explain why titanium (IV) oxide is not coloured

What is EDTA4- and what makes it a useful ion?

Describe how paper chromatography can be used to identify amino acids

Complexes formed by EDTA involve pairs of electrons on nitrogen and oxygen atoms, in the same way as complexes formed by NH3 and H2O. Explain why stability constants of EDTA complexes in solution are generally much larger than those of corresponding complexes with NH3 and H2O

What is meant by the standard electrode potential of a half cell?

How do you work out the whole cell potential using a standard electrode potential?

When is a reaction feasible?

Why might a reaction not happen even if it is 'feasible'

Why does copper prefer to have a full 3d subshell with only one electron n the 4s shell?

Why is Sc not a transition metal?

Why is zinc not a transition metal?

Why is there not much difference in energy between making the Fe2+ and Fe3+ ions?

Why are transition metals good catalysts?

Why is the co-ordination number for some complexes 4 and 6 for others?

In a ligand substitution reaction, what can cause the complex to change shape?

Transition metals in (aq) form complex ions e.g. [Fe(H2O)6]2+
Hydroxide ions remove H+ ions from water ligands.
What happens when enough H+ ions have been removed?

What colour is the: Fe(OH)2 solid?

What colour is the: Fe(OH)3 solid?

What colour is the: Cu(OH)2 solid?

What happens when you add a small amount of ammonia solution to
[Cu(H2O)6]2+?

What happens when you add excess ammonia solution to the Cu(OH)2?

Why are transition metals good heterogeneous catalysts?

What does the colour that a transition metal depend on?

Why use a filter on a colorimeter?

Ways to measure the rate of reaction:

How can you use a graph to calculate the rate at one point of the in the reaction?

What does the order of reaction with respect to a particular reactant tell you?

What does the K in the rate equation tell you?

What does the order of reaction with respect to reactant show?

What forces can hold the tertiary structure together

What is a nucleotide made up of?

What group on the base bonds to the sugar phosphate backbone

Arguments for storing genetic info

How is mRNA involved in protein synthesis

Describe the process of translation

What determines whether a bond has a permanent dipole

How can you neutralise an amine?

How do you hydrolyse an amide?

What do you need for making an ester?

In recrystallisation, why so impurities stay in solution after dissolving?

What would happen if the solute is too soluble at room temp?

Ways to make polymer production more green:

What do thermoplastics have?

What is meant by an amorphous polymer?

What affect does adding a plasticiser have?

How does cold drawing increase the crystallinity of a polymer?

When are ions formed?

Why use an acyl chloride to make an ester from a phenol?

How and why heat under reflux?

Why does hydrogen cyanide partially dissociate in water?

What is the stationary phase in TLC

How would you work out the Rf value

How can Rf values change?

Why are fragmentation patterns useful?

Why are high-resolution mass spec useful