[def123]

Hi all.
I have a couple of litres of Nitric Acid that I want to safely dispose of. I am not sure of its concentrate, but I know it's not fuming. I got it from a hydroponic lettuce grower who used it for lowering the nutrient pH (he has since sold up and moved away, so I can't just take it back) I have searched around on the net and from what I have read so far, I am looking at doing the following.

Have 20 litre plastic bucket with 5 litres of tap water in it
Add 500ml of Nitric Acid to the bucket of water
Add Soda Ash as required
Check pH with Litmus paper to reach around 7
Pour it down the sink

Now the questions:
will this work
is it safe to do in an open backyard environment
if the above will work, could I, after reaching a pH of around 7, then just add another 500ml of acid to the solution and go again
any idea of how much soda ash may be required for each 500ml neutralization?

Thanks.

[Burner]

... I am not sure of its concentrate, but I know it's not fuming ...

Have 20 litre plastic bucket with 5 litres of tap water in it
Add 500ml of Nitric Acid to the bucket of water
...

I think the nitric acid will be diluted enough for this move to be safe. To be honest, the more dilute the nitric acid, the better, but don't over-fill the bucket by adding too much water(liquid level should not exceed 1/3 of the bucket height)

Check pH with Litmus paper to reach around 7

Litmus paper can only be used to distinguish between acids and alkalis but can't be used to confirm whether the solution is neutral or not. You need pH paper, universal litmus paper or pH meter.

Pour it down the sink

In Chemistry lab we nearly never pour any chemicals to the sink. I am not sure about the best method to dispose them though.

Now the questions:
will this work
is it safe to do in an open backyard environment

It should work, but you should add soda ash slowly as CO₂ will be produced. Adding them too quicky may cause the mixture to splash out due to the large amount of gas suddenly produced. Also, a significant amout of heat will be generated, so if I were you I would add some more water to the bucket after pouring the soda ash or make the nitric acid more dilute.

if the above will work, could I, after reaching a pH of around 7, then just add another 500ml of acid to the solution and go again

Not advisable. Better to pour the neutralized liquid away each time before adding another 500ml of acid and 5L water.

any idea of how much soda ash may be required for each 500ml neutralization?

Hard to tell without knowing the concentration of nitric acid.

[def123]

Thanks Burner

[kriggy]

any idea of how much soda ash may be required for each 500ml neutralization?

Hard to tell without knowing the concentration of nitric acid.

Considering that it is 68% nitric acid, for each litre you will need aproximately 1,7 kg of solid Na₂CO₃

[Burner]

I am not sure of its concentrate, but I know it's not fuming.

Surely not 68% nitric acid