The balanced equation for the oxidation of ethanol to ethanoic acid using sodium dichromate in acidic conditions is as follows: $$3C_2H_5OH + Na_2Cr_2O_7 + 4H_2SO_4 \rightarrow 3CH_3CHO + Cr_2(SO_4)_3 + Na_2SO_4 + 7H_2O$$ (i) Deduce the oxidation numbers of chromium in the sodium dichromate reagent and in the chromium sulfate product. (ii) State the colour change observed as this reaction proceeds. (iii) Describe a test you could carry out to confirm that the organic product is an aldehyde. (iv) Give the name and structure of another organic compound that could be formed when ethanol is oxidised using acidified sodium dichromate.

Leaving Cert Chemistry Oxidation & Reduction: The balanced equation for the ox

The balanced equation for the oxidation of ethanol to ethanoic acid using sodium dichromate in acidic conditions is as follows: $$3C_2H_5OH + Na_2Cr_2O_7 + 4H_2SO_4 \rightarrow 3CH_3CHO + Cr_2(SO_4)_3 + Na_2SO_4 + 7H_2O$$ (i) Deduce the oxidation numbers of chromium in the sodium dichromate reagent and in the chromium sulfate product - Leaving Cert Chemistry - Question c - 2010

Question c

$The-balanced-equation-for-the-oxidation-of-ethanol-to-ethanoic-acid-using-sodium-dichromate-in-acidic-conditions-is-as-follows:--$$3C_2H_5OH-+-Na_2Cr_2O_7-+-4H_2SO_4-\rightarrow-3CH_3CHO-+-Cr_2(SO_4)_3-+-Na_2SO_4-+-7H_2O$$--(i)-Deduce-the-oxidation-numbers-of-chromium-in-the-sodium-dichromate-reagent-and-in-the-chromium-sulfate-product-Leaving Cert Chemistry-Question c-2010.png$

The balanced equation for the oxidation of ethanol to ethanoic acid using sodium dichromate in acidic conditions is as follows: $$3C_2H_5OH + Na_2Cr_2O_7 + 4H_2SO_4... show full transcript

Worked Solution & Example Answer:The balanced equation for the oxidation of ethanol to ethanoic acid using sodium dichromate in acidic conditions is as follows: $$3C_2H_5OH + Na_2Cr_2O_7 + 4H_2SO_4 \rightarrow 3CH_3CHO + Cr_2(SO_4)_3 + Na_2SO_4 + 7H_2O$$ (i) Deduce the oxidation numbers of chromium in the sodium dichromate reagent and in the chromium sulfate product - Leaving Cert Chemistry - Question c - 2010

Step 1

Deduce the oxidation numbers of chromium in the sodium dichromate reagent and in the chromium sulfate product.

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Answer

In sodium dichromate, $Na_2Cr_2O_7$ , the oxidation state of chromium is +6. In chromium sulfate, $Cr_2(SO_4)_3$ , the oxidation state of chromium is +3.

Step 2

State the colour change observed as this reaction proceeds.

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Answer

The colour changes from orange to green during the reaction.

Step 3

Describe a test you could carry out to confirm that the organic product is an aldehyde.

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Answer

You could heat the product with Fehling's solution. A positive result would show a brick-red precipitate or a silver mirror when using Tollens' reagent, confirming the presence of an aldehyde.

Step 4

Give the name and structure of another organic compound that could be formed when ethanol is oxidised using acidified sodium dichromate.

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Answer

Another organic compound that can be formed is ethanoic acid (acetic acid), with the structure:

   H   O
   |  ||
H--C--C--OH
   |  
   H

Alternatively, it can be represented as CH₃COOH.

Deduce the oxidation numbers of chromium in the sodium dichromate reagent and in the chromium sulfate product.

State the colour change observed as this reaction proceeds.

Describe a test you could carry out to confirm that the organic product is an aldehyde.

Give the name and structure of another organic compound that could be formed when ethanol is oxidised using acidified sodium dichromate.

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