A scientist does two tests on four white solids - AQA - GCSE Chemistry Combined Science - Question 7 - 2018 - Paper 1
Question 7
A scientist does two tests on four white solids. The solids are labelled A, B, C and D.
Test 1
Adds the sample of the solid to distilled water and stirs.
Test 2
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Worked Solution & Example Answer:A scientist does two tests on four white solids - AQA - GCSE Chemistry Combined Science - Question 7 - 2018 - Paper 1
Step 1
Identify the solids A, B, C and D.
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Answer
A is sodium oxide
because it has the highest pH or pH = 14 or is a strong alkali.
B is phosphorus oxide
because it has the lowest pH or pH = 3 or is an acid.
C is magnesium oxide
because it has the second highest pH or pH = 9 or is a weak alkali.
D is silicon dioxide
because it is neutral or pH = 7.
Step 2
Calculate the value of X.
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Answer
When 10 cm³ of solution B (pH 3) is diluted to 1000 cm³, the dilution factor is 100.
Thus, the pH will change by approximately 2 units, making the new pH:
