A milkman add a very small amount of baking soda to fresh milk. (a) why does he make the milk slightly alkaline? (b) why does the milk take a long time to set as curd?
Answers
Answer:
answer is that
Explanation:
In hot weather, milk can go 'off' very quickly due to rapid bacterial growth.. Even small amounts of lactic acid are quite distinctive with an acid sour taste, and even though it is not at all harmful, most people will reject the milk as 'bad' or having 'gone off'. If this can be removed, the milk will taste as usual and customers will accept it. This is why the milkman might add a trace of baking soda. Chemistry involved: Baking soda is a common name for sodium bicarbonate NaHCO3 [not to be confused with baking powder]. Lactic acid, systematic name 2-hydroxypropanoic acid, will be neutralised by the carbonate. ACID + CARBONATE = SALT + WATER + CARBON DIOXIDE CH3CH(OH)COOH + NaHCO3 = CH3CH(OH)COONa + H2O + CO2 Since this removes the unpleasant lactic acid taste, this makes the milk seem fresh. Baking soda is white like milk so it doesn't change its appearance.
b)Answer: As this milk is slightly more alkaline than other, therefore, acid produced to set into curd will be neutralized by baking soda added by milkman. Hence, this milk takes a longer time to set as curd.
Answer:
Becoz baking soda is a base which reacts with acids and neutralizes it. This prevents milk from getting sour and keeping it fresh for long time...
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