4. Mixtures of substances can be separated using different techniques - Edexcel - GCSE Chemistry - Question 4 - 2019 - Paper 1
Question 4
4. Mixtures of substances can be separated using different techniques.
(a) Which of the following is a mixture of substances?
A air
B carbon dioxide
C gold ... show full transcript
Worked Solution & Example Answer:4. Mixtures of substances can be separated using different techniques - Edexcel - GCSE Chemistry - Question 4 - 2019 - Paper 1
Step 1
Which of the following is a mixture of substances?
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Answer
The correct answer is A air. Air is a mixture of gases, including nitrogen, oxygen, carbon dioxide, and others, while carbon dioxide, gold, and titanium are pure substances.
Step 2
State one other mistake in Figure 5.
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Answer
Another mistake in Figure 5 is that the ink should be introduced into the side arm rather than directly into the bulb of the apparatus. This ensures that only the vaporized component is collected, preventing contamination.
Step 3
The steps needed to carry out the chromatography experiment are listed below. They are not in the correct order.
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Answer
The correct order of the steps is:
Draw a start line on the piece of paper (3)
Put small spots of the food colourings on the start line (6)
Place the paper in the beaker (4)
Put solvent in the beaker (2)
Leave the solvent to rise up the paper (1)
Remove the paper when the solvent is near the top (5).
Step 4
Explain, using Figure 6, which food colouring contains the greatest number of coloured substances.
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Answer
From Figure 6, food colouring T shows the greatest number of separated spots, indicating it contains the most colored substances. This is evident because it has multiple distinct spots, while other colourings display fewer or single spots.
Step 5
Calculate the Rf value for food colouring R.
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Answer
To calculate the Rf value, use the formula:
Rf=distancemovedbysolventdistancemovedbysubstance
In this case: Rf=8.00cm2.30cm=0.2875
Rounding to two significant figures gives an Rf value of 0.29.
