1. Distinguishing between aldehydes and ketones Can carbonyl compounds (and alcohols) act as reductants and be oxidised?

2. Tollen’s test 1. Make Tollen’s reagent as follows: Place 5 mL of 0.05 molL -1 silver nitrate in a tt and add 1 drop dilute NaOH. Then SHAKING THOROUGHLY between additions, add drops of dilute ammonia until the last of the ppte JUST disappears. 2. Divide the Tollen’s reagent into 3 CLEAN tts. 3. Add 5 drops of ethanol, ethanal and propanone respectively. 4. Place tt GENTLY in a water bath at 50 °. Leave and observe.

3. Benedict’s Test 1. To 5 mL of Benedict’s solution in a tt, add 5 drops of the test substance. Test ethanol, ethanal and propanone. 2. Heat to boiling CAREFULLY over a Bunsen Burner.

4. Questions 1. Write an equation for the reaction of ethanal with Tollen’s reagent. 2. Write an equation for the reaction of ethanal with Benedict’s reagent.

5. Answers 1. 2OH - + CH 3 CHO → CH 3 COOH + H 2 O +2e 2Ag(NH 3 ) 2 + + 2e → 2Ag + 4NH 3 2Ag(NH 3 ) 2 + + 2e → 2Ag + 4NH 3 2. Oxidation ½ equation is the same 2Cu 2+ + 2OH - + 2e → Cu 2 O + H 2 O