Consider the following equation; Cr2O7(aq)2- + 14H+(aq) + 6e- → 2Cr3+(aq) + 7H2O(I). The oxidation number of chromium changes from

Assessment: WAEC SSCE - Chemistry - 2002 (Objective) Subject: Chemistry

Question 1 Report

Consider the following equation; Cr2O7(aq)2- + 14H+(aq) + 6e- → 2Cr3+(aq) + 7H2O(I). The oxidation number of chromium changes from
Answer Details
In the given equation, the reactant Cr2O72- has chromium in the +6 oxidation state (since each oxygen atom has an oxidation number of -2, and there are seven of them, the total negative charge of the oxygen atoms is -14, and the total negative charge of the ion is -2, so the total positive charge of the chromium atoms must be +12 to balance it out). In the product side, the product Cr3+ has a +3 oxidation state. This means that the oxidation number of chromium has changed from +6 to +3, a decrease of 3. Therefore, the answer is - 2 to + 6, since chromium goes from +6 to +3.
Read lesson note on Oxidation And Reduction (JAMB)
View Answer

Related Questions

1

When concentrated sodium chloride solution is electrolysed using inert electrodes the products are?
2

Which of the following processes takes place during the production of margarine from vegetable oils?
3

Which of the following ions require the largest quantity of electricity for discharge at an electrode?
4

If two metallic ions of the same concentration migrate to a graphite cathode, the one that would be preferentially discharged is the one that has the
5

When alkynes are hydrogenated completely, they produce compounds with the general molecular formula
6

The atomic number of chlorine is 17. What is the number of electrons in a chloride ion?
7

Which of the following compounds can be represented by the molecular formula C2H6O?
8

If the relative molecular mass of an element is not a whole number, it can be deduced that the element is

Download The App On Google Playstore

Everything you need to excel in your exams

Green Bridge CBT Mobile App
Personalized AI Learning Chat Assistant
200,000+ Exam Questions Across IGCSE, JAMB, WAEC & NECO
Over 3,900 Lesson Notes
Offline Support - Learn Anytime, Anywhere
Green Bridge Timetable
Literature Summaries & Potential Questions
Track Your Performance & Progress
In-depth Explanations for Comprehensive Learning