Corrosion of ordinary iron nails in nitric acid
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As the title suggests, a regular 6.5g iron nail reacts in 90ML of 45% concentrated nitric acid (at room temperature and pressure); the reaction is very intense, with large amounts of yellow smoke and heat being produced. The entire reaction takes 10 minutes, and after that time there is still slight reaction occurring in the solution, but at least half of the iron nail has not yet reacted. I would like to ask how to ensure that iron nails react completely in nitric acid?
2Fe + 6HNO3 = 2Fe(NO3)3 + 3H2 – it’s not a complete reaction! 6.5g of FE – how much 45% nitric acid is needed? Let’s calculate it. What is the density of 45% nitric acid?
Iron is reducible, while concentrated nitric acid is oxidizing. To achieve a complete reaction, nitric acid needs to be diluted. A concentration of 5% or less should be sufficient
It has nothing to do with concentration, right? It needs to be calculated using the chemical formula~~
It is highly related to concentration. The equations on the second floor are not considered main reactions. Small amount of iron: Fe + 6HNO3 (concentrated) = Fe(NO3)3 + 3NO2↑ + 3H2O + Q. Excess iron: Fe + 4HNO3 (concentrated) = Fe(NO3)2 + 2NO2↑ + 2H2O + Q. Reaction of iron with dilute nitric acid: Small amount of iron: Fe + 4HNO3 (diluted) = Fe(NO3)3 + NO↑ + 2H2O; Fe + 2HNO3 = Fe(NO3)2 + H2. Excess iron: 3Fe + 8HNO3 (diluted) = 3Fe(NO3)2 + 2NO↑ + 4H2O. The reaction of nitric acid with mixed acids is not that simple.
The simplest way to ensure complete reaction of iron nails in nitric acid is to use an excess of nitric acid.
45% nitric acid has strong oxidizing properties; to react with 6.5 g of iron, a complete displacement reaction is required, and the total amount of nitric acid is sufficient, so it is enough to dilute it to a certain concentration in order to reduce the formation of Nox.
My answer wasn’t the best at all**…… The science guy cried
It is nitrogen dioxide. The reaction does result in the formation of nitric oxide, but nitric oxide is very unstable and can be oxidized by oxygen in the air to form nitrogen dioxide