Required Practical 4 Tests for Ions

What chemicals test for Group 2 ions?

barium chloride and sodium hydroxide, or barium chloride and sulfuric acid

Describe the test for Group 2 ions using sodium hydroxide:

add barium chloride, add excess sodium hydroxide, mix well

What is a positive result for barium in a test for Group 2 ions using sodium hydroxide?

colourless solution

What is a positive result for calcium in a test for Group 2 ions using sodium hydroxide?

white precipitate

What is a positive result for magnesium in a test for Group 2 ions using sodium hydroxide?

white precipitate

What is a positive result for strontium in a test for Group 2 ions using sodium hydroxide?

slight white precipitate

Describe the test for Group 2 ions using sulfuric acid:

add barium chloride, add excess sulfuric acid, mix well

What is a positive result for barium in a test for Group 2 ions using sulfuric acid?

white precipitate

What is a positive result for calcium in a test for Group 2 ions using sulfuric acid?

slight white precipitate

What is a positive result for magnesium in a test for Group 2 ions using sulfuric acid?

colourless solution

What is a positive result for strontium in a test for Group 2 ions using sulfuric acid?

white precipitate

What chemicals test for ammonium ions?

sodium hydroxide and red litmus paper

Describe the test for ammonium ions:

add sodium hydroxide, warm solution, test fumes by holding up damp red litmus paper

What is a positive result in the test for ammonium ions?

damp red litmus paper turns blue

When does damp red litmus paper turn blue?

in contact with alkali

When does damp blue litmus paper turn red?

in contact with acid

Describe the aqueous solution test for hydroxide ions:

test solution with red litmus paper

What is a positive result in the aqueous solution test for hydroxide ions?

red litmus paper turns blue

Describe the ammonia test for hydroxide ions:

add ammonia, place on filter paper in a petri dish, place damp red litmus paper at the other side, add a lid

What is a positive result in the ammonia test for hydroxide ions?

damp red litmus paper turns blue

What chemicals test for hydroxide ions?

red litmus paper or ammonia and red litmus paper

What chemicals test for carbonate ions?

hydrochloric acid, calcium hydroxide

Describe the test for carbonate ions:

add hydrochloric acid, transfer gas into delivery tube, bubble gas through calcium hydroxide

What is a positive result in the test for carbonate ions?

limewater turns cloudy

Write the equation for the first half of the carbonate ion test:

Na₂CO₃ + 2HCl→2NaCl + H₂O + CO₂

Write the equation for the second half of the carbonate ion test:

Ca(OH)₂ + CO₂→CaCO₃+H₂O

What chemicals test for sulfate ions?

hydrochloric acid, barium chloride

Describe the test for sulfate ions:

add equal volumes of hydrochloric acid and barium chloride, add small volume of hydrochloric acid

What is a positive result in the test for sulfate ions?

white precipitate

Write the equation for the test for sulfate ions using magnesium sulfate:

MgSO₄+BaCl₂→BaSO₄+MgCl₂

What chemicals test for halide ions?

nitric acid, silver nitrate, ammonia

Describe the test for halide ions:

add nitric acid, add silver nitrate, split in half, add excess dilute ammonia to one half and add excess concentrated ammonia to the other half

What is a positive result for chlorine in the test for halide ions after adding silver nitrate?

white precipitate

What is a positive result for bromine in the test for halide ions after adding silver nitrate?

cream precipitate

What is a positive result for iodine in the test for halide ions after adding silver nitrate?

yellow precipitate

Which of the halide ions dissolves once dilute ammonia is added?

chloride

Which of the halide ions dissolves once concentrated ammonia is added?

bromide

Which of the halide ions does not dissolve when ammonia is added?

iodide

What chemicals test for group 7 ions in solid salts?

sulfuric acid, blue litmus paper

Describe the test for group 7 ions in solid salts:

add sulfuric acid, test fumes with blue litmus paper

What is a positive result for chlorine in a test for group 7 ions in solid salts?

white steamy fumes, blue litmus paper turns red

What is a positive result for bromine in a test for group 7 ions in solid salts?

orange fumes, blue litmus paper turns red

What is a positive result for iodine in a test for group 7 ions in solid salts?

purple fume, purple-black solid, blue litmus paper turns red