Zinc reacts with very dilute nitric acid…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Zinc reacts with very dilute nitric acid. The nitrogen is reduced all the way to the ammonium ion, and it stays in the solution as ammonium nitrate. The skeleton equation is . Balance it.
Need a reminder? The key ideaShow
The total rise in oxidation number equals the total fall: electrons lost equal electrons gained. Match the changes first. Then balance the atoms that did not change, charge, hydrogen and oxygen.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Oxidation numbers. Zinc goes from to , a rise of 2. The nitrogen that becomes goes from to , a fall of 8.
Step 2. Match. Eight electrons are gained by one nitrogen atom. Four zinc atoms lose . So .
Step 3. Nitrogen. The right side holds nitrogen atoms in the zinc nitrate and in the ammonium nitrate. That is 10, so 10 molecules of .
Step 4. Hydrogen and oxygen. Ten hydrogen atoms on the left. The ammonium ion takes 4, so 6 remain, and they make 3 water molecules. Oxygen: 30 on the left, and on the right.
Answer: .
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