Test-tube reactions

Question 1

Give the test for alkenes and the results

Answer 1

1. Shake with bromine water

• Orange to colourless

Question 2

Give the test for haloalkanes and the result

Answer 2

1. Add NaOH and warm to substitute the halide ion
2. Acidify with NHO3 to remove carbonate ions
3. Add AgNO3
   - White ppt: AgCl
   - Cream ppt: AgBr
   - Yellow ppt: AgI
4. Add dilute ammonia
   - AgCl precipitate will dissolve
5. Add conc. ammonia
   - AgBr ppt will dissolve but AgI ppt will remain

Question 3

Give the test for primary and secondary alcohol (and aldehydes) and give the result

Answer 3

1. Add acidified K2Cr2O7
2. Warm

• Solution will turn Orange to Green

Question 4

Give the test for aldehydes and the result

Answer 4

1. Warm with Tollens reagent

• Silver mirror forms

Question 5

Give the test for carboxylic acids and the result

Answer 5

1. Add Na2CO3

• Effervescence

Question 6

Give the test for H2 gas and the result

Answer 6

1. Apply a lit splint

• Squeaky pop occurs

Question 7

Give the test for CO2 gas and the result

Answer 7

1. Bubble through lime water

• Solution turns cloudy

Question 8

Give the test for O2 gas and the result

Answer 8

1. Apply a glowing splint

• The splint will relight

Question 9

Give the test for SO4 2- ions and give the result

Answer 9

1. Add BaCl2 solution

• A white ppt will form

Question 10

Give the test for CO3 2- ions and the result

Answer 10

1. Add any acid (eg. HCl)

• Effervescence