Practical investigations
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Can you throw some light on the kinetics of the reaction between nitric acid and magnesium ?
Corrie writes
There is not much information available on the kinetics of this reaction, although there is one set of data in the article by Williams & Hacker referred to in the React tutorial Investigating the rate of the reaction of metals with acids, and which can be downloaded. Nitric acid appears to react more slowly than hydrochloric acid.
A few students have tried to include nitric acid in their investigations and have run into complications - if you search the React site under 'nitric acid' you will find the relevant FAQs that have been answered.
The reason that nitric acid is not usually included in practical investigations of this kind is that its reaction with metals is not the expected one, producing a metal nitrate and hydrogen. Instead nitric acid's oxidising properties lead to the formation of various nitrogen oxides, depending on concentration. Only in very dilute solution with magnesium is hydrogen produced.
With copper, for instance, which does not react to produce hydrogen with other acids, nitrogen dioxide is produced with conc. nitric acid and nitric oxide (NO) with dilute acid. With zinc and very dilute nitric acid nitrous oxide (N2O) is formed.
I hope this has thrown at least some light on this complicated reaction for you.
Always carry out a risk assessment and check with your teacher before starting any practical work.
Risk assessment
Before attempting any practical work based on the advice and suggestions on this website, you must do the following. Identify any hazards, assess the risks from these hazards, and then decide appropriate control measures to reduce the risks. You must have these approved by those in authority in your school or college laboratory. Do not rely on what is said on this website.
For further guidance see our tutorial on Risk Assessment.
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updated: 22 July 2007
