Chromatography

Printer ink is a mixture of chemicals.

What is the name given to a mixture that has been designed as a useful product?

Tick () one box.

A student used chromatography to investigate the colours in a printer ink.

Figure 2 shows the chromatogram.

The student used a ruler for the start line.

What would the student have used to draw the start line?

Give one reason for your answer.

Determine the R_f value of the red colour.

Use the equation:

Distance moved by red colour

Distance moved by solvent

Table 2 shows the R_f values of four blue colours.

The student determined that the R_f value of the blue colour in the printer ink was 0.86

Suggest which blue colour was used in the printer ink.

Give one reason for your answer.

Printer ink is a mixture of chemicals.

A student used chromatography to investigate the colours in a printer ink.

The student put a spot of the printer ink on the start line.

Figure 4 shows the results.

Explain why the red colour did not move from the start line.

The blue colour moved 6.4 cm up the chromatogram.

The R_f value of the blue colour is 0.87

Calculate the distance moved by the solvent.

Give your answer to 2 significant figures.

There were four colours in the printer ink.

Suggest one reason why only three colours were visible on the chromatogram.

Suggest how the student could use chromatography to show there were four colours in the printer ink.

Chromatography is used to separate mixtures.

Chromatography involves a mobile phase and one other phase.

What is the other phase in chromatography? Tick (✓) one box.

Why do the substances in the mixture separate in the mobile phase?

How many spots will be produced on the chromatogram of a pure compound?

In a chromatography experiment, a blue colour moved 4.77 cm. The solvent moved 5.30 cm. Calculate the R_f value for the blue colour.

Black ink is a mixture of several colours. Plan an experiment using paper chromatography to:

• separate the colours in black ink

• identify the colours from their R_f values.

Chromatography is used to separate mixtures.

Chromatography involves a mobile phase and one other phase.

What is the other phase in chromatography? Tick (✓) one box.

Why do the substances in the mixture separate in the mobile phase?

How many spots will be produced on the chromatogram of a pure compound?

In a chromatography experiment, a blue colour moved 4.77 cm. The solvent moved 5.30 cm. Calculate the R_f value for the blue colour.

Black ink is a mixture of several colours. Plan an experiment using paper chromatography to:

• separate the colours in black ink

• identify the colours from their R_f values.

A student investigated the colours in a brown ink using chromatography.

Figure 10 shows the apparatus used.

Give two errors made by the student.

Describe the problem each error would cause.

A different student set up the apparatus correctly.

Figure 11 shows the results.

Give two conclusions the student can make from Figure 11 about the four colours in the brown ink.

Why was the green colour still on the start line at the end of the experiment?

Tick (✓) one box.

A student calculated the R_f value of a colour to be 0.24

The colour moved 1.8 cm from the start line.

Calculate the distance the solvent moved.

Use the equation:

A student investigated the colours in a brown ink using chromatography.

Figure 1 shows the apparatus used.

Give two errors made by the student. Describe the problem each error would cause.

A different student set up the apparatus correctly. Figure 2 shows the results.

Give two conclusions the student can make from Figure 2 about the four colours in the brown ink.

Why was the green colour still on the start line at the end of the experiment? Tick (✓) one box.

A student calculated the R_f value of a colour to be 0.24 The colour moved 1.8 cm from the start line. Calculate the distance the solvent moved. Use the equation:

This question is about mixtures.

Which substance is a mixture? Tick (✓) one box.

Food colourings are often mixtures of dyes. What name is given to mixtures that are designed as useful products?

A student investigated a purple food colouring, Y, using chromatography. The student compares Y with dyes A, B and C.

Figure 8 shows the apparatus used.

Chromatography involves a stationary phase and a mobile phase.

Draw one line from each phase to what is used for that phase. Use Figure 8. Phase What is used

Figure 9 shows the student’s results.

What three conclusions can you make about the dyes in food colouring Y ?

In a different experiment a student recorded these results: Distance moved by dye G = 60 mm Distance moved by solvent = 80 mm Calculate the R_f value of dye G.

This question is about chromatography of food colouring.

Food colouring is a formulation. What is a formulation?

Explain how paper chromatography separates the dyes in a food colouring. Do not give details of how to do the experiment.

Explain how the student could tell from the chromatogram that the food colouring contained more than one dye.

Explain how the student could use chromatography to identify unknown dyes in the food colouring.

A student used paper chromatography to identify the colours in a black ink.

Figure 5 shows the student’s results.

What colours are in the black ink?

Suggest which colour is least soluble in the solvent.

Give a reason for your answer.

Use Figure 5 to complete Table 2

Calculate the R_f value for the green colour.

Use the equation: