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 Identifying negative ions - Carbonates test: 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

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

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Answer

The formula for potassium sulfate can be derived from the ions present in the compound. Since potassium ions are represented as K^+ and sulfate ions as SO_4^{2-}, the formula must balance the charges. Therefore:

$ext{K}_2 ext{SO}_4$

This indicates there are two potassium ions for every sulfate ion.

Step 2

6(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. Therefore, you should place a cross (X) in box B.

Step 3

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

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Answer

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

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

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Answer

To test for carbonate ions, follow these steps:

Take a small sample of solid calcium carbonate and place it in a test tube.
Add a few drops of dilute hydrochloric acid (HCl) to the calcium carbonate.
Observe the reaction; if carbonate ions are present, effervescence (bubbles) will occur as carbon dioxide (CO_2) gas is released.
To confirm the presence of CO_2, it can be bubbled into limewater (a solution of calcium hydroxide), which will turn milky, indicating the presence of carbonate ions.

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

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

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

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

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

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