Answer
Verified
388.8k+ views
Hint: Chromium in the product of this reaction is existing as $\left( { Cr }_{ 2 }{ \left( { SO }_{ 4 } \right) }_{ 3 } \right) $ . Oxidation state of Sulphate ion is -2. Since, the compound here is a neutral molecule, the overall oxidation state of the compound is zero. Oxidation state of chromium can be found by a simple equation using the above given facts.
Complete step by step answer:
The reaction here is when acidified potassium dichromate is reacted with potassium iodide, so first of all, we can give the balanced chemical equation for this reaction.
In the product form, Cr is existing as the compound $\left( { Cr }_{ 2 }{ \left( { SO }_{ 4 } \right) }_{ 3 } \right) $ .
Oxidation state of chromium can be found in the following method given below:
Consider the oxidation state of Cr as ‘x’.
Since the compound here is a neutral molecule, some of the oxidation states of all the elements in the compound will be zero.
We know that the oxidation state of sulphate ion is -2.
Therefore,
Hence, the oxidation state of Cr in the product is +3.
So, option (C) +3 is the correct answer.
Additional Information:
In the question, it is given that potassium iodide is oxidised into${ I }_{ 2 }$. And this has been validated by the fact that the oxidation state of I in KI is -1 which is increased to 0 in ${ I }_{ 2 }$. Since there is an increase in oxidation state is happening here, and hence it is being referred to as iodine is being ‘oxidised’.
Oxidant: Oxidant or oxidising agent is referred to as a chemical compound which oxidises other compounds by itself getting reduced in a redox chemical reaction. In this question, when we consider the reaction , we can see that the oxidation state of Cr is getting reduced from +6 to +3 and so ${ K }_{ 2 }{ Cr }_{ 2 }{ O }_{ 7 }$ acts as an oxidising agent in this reaction.
Reductant: Reductant or reducing agent is referred to as a chemical compound which reduces other compounds by itself getting oxidised in a redox chemical reaction. In this question, when we consider the reaction , we can see that the oxidation state of I is getting reduced from -1 to 0 and so KI acts as a reducing agent in this reaction.
Increase in oxidation state is known as oxidation while a decrease in oxidation state is known as reduction.Increase in the oxidation state is actually referring to loss of electrons and decrease in oxidation state is actually the gain of electrons.
Note: Elements in their pure state have zero oxidation state whereas oxidation state of a pure ion is equal to its ionic charge. For example: ${ Ca }^{ 2+ }$ has an oxidation state of +2 , oxidation state of carbon in graphite and diamond is 0, oxidation state of ${ H }_{ 2 }$,${ N }_{ 2 }$,${ Cl }_{ 2 }$ are 0.
Complete step by step answer:
The reaction here is when acidified potassium dichromate is reacted with potassium iodide, so first of all, we can give the balanced chemical equation for this reaction.
$\ { { K }_{ 2 }Cr_{ 2 }{ O }_{ 7 }\ +\ 7{ H }_{ 2 }{ SO }_{ 4 }\ +\ 6KI\ \rightarrow \ { 4K }_{ 2 }{ SO }_{ 4 }\ +\ { Cr }_{ 2 }{ \left( { S }O_{ 4 } \right) }_{ 3 }\ +\ { 7H }_{ 2 }O\ +\ { 3I }_{ 2 } }$
In the product form, Cr is existing as the compound $\left( { Cr }_{ 2 }{ \left( { SO }_{ 4 } \right) }_{ 3 } \right) $ .
Oxidation state of chromium can be found in the following method given below:
Consider the oxidation state of Cr as ‘x’.
Since the compound here is a neutral molecule, some of the oxidation states of all the elements in the compound will be zero.
We know that the oxidation state of sulphate ion is -2.
Therefore,
$\ { \Rightarrow \ 2x\ +\ \left(3\times -2\right) \ =\ 0\\ \Rightarrow \ 2x\ -\ 6\ =\ 0\\ \Rightarrow\ 2x\ =\ 6\\ \Rightarrow \ x\ =\ +3 }$
Hence, the oxidation state of Cr in the product is +3.
So, option (C) +3 is the correct answer.
Additional Information:
In the question, it is given that potassium iodide is oxidised into${ I }_{ 2 }$. And this has been validated by the fact that the oxidation state of I in KI is -1 which is increased to 0 in ${ I }_{ 2 }$. Since there is an increase in oxidation state is happening here, and hence it is being referred to as iodine is being ‘oxidised’.
Oxidant: Oxidant or oxidising agent is referred to as a chemical compound which oxidises other compounds by itself getting reduced in a redox chemical reaction. In this question, when we consider the reaction , we can see that the oxidation state of Cr is getting reduced from +6 to +3 and so ${ K }_{ 2 }{ Cr }_{ 2 }{ O }_{ 7 }$ acts as an oxidising agent in this reaction.
Reductant: Reductant or reducing agent is referred to as a chemical compound which reduces other compounds by itself getting oxidised in a redox chemical reaction. In this question, when we consider the reaction , we can see that the oxidation state of I is getting reduced from -1 to 0 and so KI acts as a reducing agent in this reaction.
Increase in oxidation state is known as oxidation while a decrease in oxidation state is known as reduction.Increase in the oxidation state is actually referring to loss of electrons and decrease in oxidation state is actually the gain of electrons.
Note: Elements in their pure state have zero oxidation state whereas oxidation state of a pure ion is equal to its ionic charge. For example: ${ Ca }^{ 2+ }$ has an oxidation state of +2 , oxidation state of carbon in graphite and diamond is 0, oxidation state of ${ H }_{ 2 }$,${ N }_{ 2 }$,${ Cl }_{ 2 }$ are 0.
Recently Updated Pages
Basicity of sulphurous acid and sulphuric acid are
Three beakers labelled as A B and C each containing 25 mL of water were taken A small amount of NaOH anhydrous CuSO4 and NaCl were added to the beakers A B and C respectively It was observed that there was an increase in the temperature of the solutions contained in beakers A and B whereas in case of beaker C the temperature of the solution falls Which one of the following statements isarecorrect i In beakers A and B exothermic process has occurred ii In beakers A and B endothermic process has occurred iii In beaker C exothermic process has occurred iv In beaker C endothermic process has occurred
The branch of science which deals with nature and natural class 10 physics CBSE
The Equation xxx + 2 is Satisfied when x is Equal to Class 10 Maths
How do you arrange NH4 + BF3 H2O C2H2 in increasing class 11 chemistry CBSE
Is H mCT and q mCT the same thing If so which is more class 11 chemistry CBSE
Trending doubts
Difference Between Plant Cell and Animal Cell
Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE
How do you solve x2 11x + 28 0 using the quadratic class 10 maths CBSE
Select the correct plural noun from the given singular class 10 english CBSE
What organs are located on the left side of your body class 11 biology CBSE
The sum of three consecutive multiples of 11 is 363 class 7 maths CBSE
What is the z value for a 90 95 and 99 percent confidence class 11 maths CBSE
Fill the blanks with the suitable prepositions 1 The class 9 english CBSE
How many squares are there in a chess board A 1296 class 11 maths CBSE