2020-07-20

Nitric acid

Reagents
 100g H2SO4 98% (1 mole)
  84.9g NaNO3 (1 mole)
  NaOH solution (trap)

Procedure:
250ml round bottom flask was charged with 84.9 grams of NaNO3 and 100 grams of concentrated sulphuric acid ``was added. Simple distillation setup with NaOH trap was mantled and reaction flask was heated.
The heating was stopped when the reaction mixture solidified.

The product received in receiver flask weight was 50.5g, volume 33.5ml and it's temperature was 15 C. 
From the density table we found that density of about 1.5075 was equivalent to concentration of 97.5%, so the yield is 49.24 grams of pure HNO3.

Reaction stoichiometry: H2SO4 + NaNO3 -> HNO3 + NaHSO4

Theoretical yield – 1 mole of HNO3 (63 grams)
Practical yield – 0.78 mole (49.24 grams) 78.16%

Notes:
During the distillation a brown gas was produced in reaction flask (NO2). The foaming was observed. Foaming was proportional to the heating. After cooling the reaction mixture the foaming decreased (in the future use larger flask). 


The product was yellow due to some NO2 was dissolved. There was no need to purify.
Such concentrated HNO3 is hard to store, it fumes a lot and it builds a pressure inside a bottle so it requires frequent venting.. It's fumes corrode standard laboratory blue caps.

Safety:
    sulphuric acid is corrosive
    nitric acid is corrosive and it's a strong oxidizer. Work without gloves (latex, nitrile), because they will burst into flames when spill occur

The trap presented here should be mantled differently using inverted funnel. This one is prone to suck-back and ruining the product.

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