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Question Disposal of concentrated Nitric acid

6 months 1 week ago #41373 by Cookaburra
Hi, can someone explain the reasoning behind Cleapss disposal instructions that state the use of 1M sodium carbonate to neutralise the HNO3 before it is poured down the drain? During practicals acid of up to 2M is poured down the drain frequently.

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6 months 1 week ago #41375 by prep_room_boy
Theory is that it is better to throw water and salts down the drain rather than rely on dilution of an acid. Minimum environmental impact etc.....

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6 months 1 week ago - 6 months 1 week ago #41378 by Baldilocks
Depends on the quantity. 'Scholar' quantities will be smaller and likely disposed over a period of minutes or longer meaning that the chemical isn't going to hit the drain all at once - it will be diluted by other liquids from the toilets, kitchens etc.
When CLEAPSS are talking about 'disposal' they HAVE to assume the worst - that you need to get rid of a lot - a 2litre bottle all at once.
Remember that tap water is a weak base with a molarity of its own - depending on how hard your local water is. If you measure that you can calculate how much tap water you need to dilute a large amount of acid.
Ian

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