6 (a) Potassium sulfate contains potassium ions, K^+, and sulfate ions, SO_4^{2-}. Use this information to give the formula of potassium sulfate. (b) A flame test is carried out on a solid potassium salt. What colour is produced in the flame by the potassium ions? Put a cross (X) in the box next to your answer. A green B lilac C red D yellow (c) Calcium carbonate is formed as a precipitate when sodium carbonate solution is mixed with calcium nitrate solution. (i) Write the word equation for the reaction. (ii) Describe a test to show that solid calcium carbonate contains carbonate ions.

GCSE Edexcel Chemistry Ionic Compounds: 6 (a) Potassium sulfate contains

6 (a) Potassium sulfate contains potassium ions, K^+, and sulfate ions, SO_4^{2-} - Edexcel - GCSE Chemistry - Question 6 - 2018 - Paper 1

Question 6

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6 (a) Potassium sulfate contains potassium ions, K^+, and sulfate ions, SO_4^{2-}. Use this information to give the formula of potassium sulfate. (b) A flame test i... show full transcript

Worked Solution & Example Answer:6 (a) Potassium sulfate contains potassium ions, K^+, and sulfate ions, SO_4^{2-} - Edexcel - GCSE Chemistry - Question 6 - 2018 - Paper 1

Step 1

a) Use this information to give the formula of potassium sulfate.

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Answer

The formula of potassium sulfate is K_2SO_4. This is derived from the one potassium ion, K^+, combining with one sulfate ion, SO_4^{2-}. Since two potassium ions are needed to balance the charge of the sulfate ion, the formula includes two potassium ions, making it K_2SO_4.

Step 2

b) What colour is produced in the flame by the potassium ions?

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Answer

The colour produced in the flame by potassium ions is lilac (B). In a flame test, potassium imparts a characteristic lilac or light purple colour, which is distinctive for identification.

Step 3

c (i) Write the word equation for the reaction.

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The word equation for the reaction between sodium carbonate and calcium nitrate to form calcium carbonate is:

Sodium carbonate + Calcium nitrate → Calcium carbonate + Sodium nitrate.

Step 4

c (ii) Describe a test to show that solid calcium carbonate contains carbonate ions.

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Answer

To test for carbonate ions in solid calcium carbonate, the following steps can be performed:

Add a few drops of dilute hydrochloric acid (HCl) to a small sample of the solid calcium carbonate.
Observe the reaction: The formation of bubbles of carbon dioxide (CO_2) gas indicates that carbonate ions (CO_3^{2-}) are present.
The gas can be further tested by bubbling it through limewater, which will turn cloudy if carbonate ions are present.

6 (a) Potassium sulfate contains potassium ions, K^+, and sulfate ions, SO_4^{2-} - Edexcel - GCSE Chemistry - Question 6 - 2018 - Paper 1

Worked Solution & Example Answer:6 (a) Potassium sulfate contains potassium ions, K^+, and sulfate ions, SO_4^{2-} - Edexcel - GCSE Chemistry - Question 6 - 2018 - Paper 1

a) Use this information to give the formula of potassium sulfate.

b) What colour is produced in the flame by the potassium ions?

c (i) Write the word equation for the reaction.

c (ii) Describe a test to show that solid calcium carbonate contains carbonate ions.

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