Practicals

Question 1

What is chromatography?

Answer 1

separating mixtures of coloured compounds

Question 2

What are the paper or thin layer of absorbent material examples of?

Answer 2

stationary phase

Question 3

what is the solvent?

Answer 3

the mobile phase

Question 4

describe the chromatography method?

Answer 4

• add the concentrated spot of mixture to the stationary phase
• end of stationary phase is suspended in the solvent (mobile phase)
• pigments/compounds move different distances according to their solubility
• if compounds aren’t visible a stain is required
• end before solvent front reaches the end of the stationary phase

Question 5

How do you calculate Rf values?

Answer 5

Rf = distance moved by compound/distance moved by solvent

Question 6

what is the Rf value always less than?

Answer 6

1

Question 7

what does it mean if the Rf value is higher?

Answer 7

the higher the Rf value, the more soluble the compound is in the solvent

Question 8

What colour change does DCPIP undergo when reduced?

Answer 8

blue –> colourless

Question 9

What does DCPIP replace?

Answer 9

DCPIP replaces NADP as the electron acceptor in the LDR

the rate of colour change is proportional to the rate of the LDR and the amount of DCPIP formed

Question 10

Explain the affect of increasing temperature on the rate of respiration in yeast

Answer 10

• respiration is controlled by enzymes
• as temp increases the kinetic energy increases, so more ESCs are formed
• above the optimum the enzyme denatures so the rate of reaction decreases