In basic solution, hydrogen peroxide oxidises chromium(III) hydroxide to chromate ions: Cr(OH)₃ +…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
In basic solution, hydrogen peroxide oxidises chromium(III) hydroxide to chromate ions: . Balance it using .
Need a reminder? The key ideaShow
In acid: balance the atoms, then oxygen with , hydrogen with , and charge with electrons. In base, add to both sides to remove the . Make the electrons equal, add the halves, and cancel.
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 half. . Charge: on both sides. Oxygen: 8 and 8. Hydrogen: 8 and 8.
Step 2. Reduction half. .
Step 3. Match. The smallest number that 3 and 2 divide into is 6. Multiply the first half by 2 and the second by 3.
Step 4. Add. . Cancel 6 from both sides.
Answer: . The coefficients are 2, 3, 4 and 8.
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