Test for Ions Flashcards Preview

A-level Chemistry > Test for Ions > Flashcards

Flashcards in Test for Ions Deck (21):
1

Name the 2 tests for Group 2 ions

  •  Dilute sodium hydroxide
  •  Dilute sulfuric acid

2

Test for Group 2 Ions

Describe what you would do using dilute sodium hydroxide

  1. Add 10 drops of barium chloride in test tube
  2. Add 10 drops of sodium hydroxide in test tube & mix well
  3. Add sodium hydroxide, dropwise, until in excess
    • Test tube shouldn't be more than half-way full
  4. Repeat this test with calcium bromide, magnesium chloride and strontium chloride

3

Test for Group 2 Ions

Describe what you would do using dilute sulfuric acid

  1. Place about 10 drops of barium chloride in test tube
  2. Add 10 drops of sulfuric acid in test tube & mix well
  3. Add sulfuric acid, dropwise, until in excess
    • Test tube shouldn't be more than half-way full
  4. Repeat this test with calcium bromide, magnesium chloride and strontium chloride

4

Test for Group 2 Ions

Results when using dilute sodium hydroxide: fill in the blanks

5

Describe the test for ammonia gas

  • Ammonia gas is alkaline
  • Can test for it using damp piece of red litmus paper
  • If ammonia present = paper turns blue

6

Testing for Ammonia

Why does red litmus paper have to be damp?

So ammonia gas can dissolve

7

If you add hydroxide ions to solution containing ammonium ions (NH4+), what it produce?

ammonia gas and water

8

Write an equation to show the reaction between hydroxide ions and ammonium ions

9

Describe the test for ammonium ions

  1. Add dilute sodium hydroxide solution to unknown substance in test tube & gently heat mixture
  2. If ammonia given off = ammonium ions must be present

10

Write the equation for the test for sulfate ions

11

Hydroxide ions make solution ____

alkaline

12

Describe the test for hydroxide ions

  1. Dip piece of red litmus paper into solution
  2. If hydroxide ions present = paper turns blue

13

Describe the test for carbonate ions (CO32-)

  1. Add dilute hydrochloric acid = solution with carbonate ions will fizz
  2. Bubble gas (CO2) through test tube of limewater and watch what happens
  3. Limewater = cloudy = carbonate ions in solution

14

Why is that when you add dilute hydrochloric acid to a solution with carbonate ions, it will fizz?

∵ carbonate ions react with hydrogen ions in acid to give carbon dioxide

15

Write the equation of carbonate ions reacting with hydrogen ions

16

Test for Group 2 Ions

Results when using dilute sulfuric acid: fill in the blanks

17

Describe the test for halide ions in solid salts using
concentrated sulfuric acid

  1. Add small amount of solid potassium chloride in test tube
  2. Add few (2 to 5) drops of concentrated sulfuric acid
  3. Test gas produced with moist blue litmus paper
    • Make sure litmus paper doesn't touch side of tube
  4. Repeat experiment with solid potassium bromide
    • Test gas produced using strip of filter paper dipped in acidified potassium dichromate solution
  5. Repeat experiment with solid potassium iodide 
    • Test gas produced using strip of filter paper dipped in lead nitrate solution 

18

Name 2 safety procedures when testing for halide ions in solid salts using concentrated sulfuric acid

  • Gloves must be worn 
  • Must be done in fume cupboard

19

State the results of when potassium chloride reacts with concentrated sulfuric acid. Include the paper result.

20

State the results of when potassium bromide reacts with concentrated sulfuric acid. Include the paper result.

21

State the results of when potassium iodide reacts with concentrated sulfuric acid. Include the paper result.