Answer
425.4k+ views
Hint: The formula for Normality is, \[{\text{Normality = }}\frac{{{\text{Weight of Solute}}}}{{{\text{Equivalent weight of Solute }} \times {\text{ Volume of solution}}}}\]
Potassium permanganate will give the following reaction in acidic media.
\[\mathop {KMn{O_4}}\limits_{Mn = + 7} + 5{e^ - } \to M{n^{ + 2}}\]
Formula used: \[{\text{Normality = }}\frac{{{\text{Weight of Solute}}}}{{{\text{Equivalent weight of Solute }} \times {\text{ Volume of solution}}}}\]
Complete step by step answer:
Here, we are asked to find the weight of \[KMn{O_4}\] required to form its one litre 1N solution. We can use the formula of normality and can easily find the weight of \[KMn{O_4}\] required.
\[{\text{Normality = }}\frac{{{\text{Weight of Solute}}}}{{{\text{Equivalent weight of Solute }} \times {\text{ Volume of solution}}}}\]
Here we are given the normality of the resultant solution, which is 1.
We will need to find the equivalent weight of \[KMn{O_4}\] in order to use the formula of its normality.
-We know that \[KMn{O_4}\] is neither an acid nor a base but it will give a redox reaction in an acidic medium. Let’s see how it will react.
\[\mathop {KMn{O_4}}\limits_{Mn = + 7} + 5{e^ - } \to M{n^{ + 2}}\]
So, we can say that the number of electrons gained in this reaction by a Manganese atom is 5.
So, we know that \[{\text{Equivalent weight of Redox reagent = }}\frac{{{\text{Molecular weight of reagent}}}}{{{\text{Number of }}{{\text{e}}^ - }{\text{ lost or gained}}}}\]
We can find the molecular weight of \[KMn{O_4}\] by following the formula.
Molecular weight of \[KMn{O_4}\] = Atomic weight of K + Atomic weight of Mn + 4(Atomic weight of O),
Molecular weight of \[KMn{O_4}\] = 39 + 55 + 4(16),
Molecular weight of \[KMn{O_4}\] = 39 + 55 + 64
Molecular weight of \[KMn{O_4}\] = 158 \[gmmo{l^{ - 1}}\].
So, we can write the formula of equivalent weight of \[KMn{O_4}\] as,
\[{\text{Equivalent weight = }}\frac{{158}}{5}\],
\[{\text{Equivalent weight = 31}}{\text{.6}}\]\[gmo{l^{ - 1}}\].
So, we can write the Normality as,
\[{\text{Normality = }}\frac{{{\text{Weight of Solute}}}}{{{\text{Equivalent weight of Solute }} \times {\text{ Volume of solution}}}}\]
We know that the equivalent weight of solute is 31.4 \[{\text{gmol}^{ - 1}}\] and the volume of solution is given 1 liter. So,
\[1 = \frac{{{\text{Weight of KMn}}{{\text{O}}_4}}}{{31.6 \times 1}}\]
\[{\text{Weight of KMn}}{{\text{O}}_4} = 1 \times 31.6 \times 1\]
\[{\text{Weight of KMn}}{{\text{O}}_4} = 31.6gm\]
Hence we can say that we need to dissolve 31.6 g of potassium permanganate in order to prepare 1 liter 1N solution.
So, the correct answer is option (C) 31.60 g.
Note:
Do not get confused between Normality and Molarity, remember that Normality uses equivalent weight of solute and in molarity, molecular weight of solute is used. Remember that Potassium permanganate will gain 5 electrons in acidic medium and will get reduced while if the reaction is in neutral medium, then it will gain only 3 electrons in the process of reduction.
Potassium permanganate will give the following reaction in acidic media.
\[\mathop {KMn{O_4}}\limits_{Mn = + 7} + 5{e^ - } \to M{n^{ + 2}}\]
Formula used: \[{\text{Normality = }}\frac{{{\text{Weight of Solute}}}}{{{\text{Equivalent weight of Solute }} \times {\text{ Volume of solution}}}}\]
Complete step by step answer:
Here, we are asked to find the weight of \[KMn{O_4}\] required to form its one litre 1N solution. We can use the formula of normality and can easily find the weight of \[KMn{O_4}\] required.
\[{\text{Normality = }}\frac{{{\text{Weight of Solute}}}}{{{\text{Equivalent weight of Solute }} \times {\text{ Volume of solution}}}}\]
Here we are given the normality of the resultant solution, which is 1.
We will need to find the equivalent weight of \[KMn{O_4}\] in order to use the formula of its normality.
-We know that \[KMn{O_4}\] is neither an acid nor a base but it will give a redox reaction in an acidic medium. Let’s see how it will react.
\[\mathop {KMn{O_4}}\limits_{Mn = + 7} + 5{e^ - } \to M{n^{ + 2}}\]
So, we can say that the number of electrons gained in this reaction by a Manganese atom is 5.
So, we know that \[{\text{Equivalent weight of Redox reagent = }}\frac{{{\text{Molecular weight of reagent}}}}{{{\text{Number of }}{{\text{e}}^ - }{\text{ lost or gained}}}}\]
We can find the molecular weight of \[KMn{O_4}\] by following the formula.
Molecular weight of \[KMn{O_4}\] = Atomic weight of K + Atomic weight of Mn + 4(Atomic weight of O),
Molecular weight of \[KMn{O_4}\] = 39 + 55 + 4(16),
Molecular weight of \[KMn{O_4}\] = 39 + 55 + 64
Molecular weight of \[KMn{O_4}\] = 158 \[gmmo{l^{ - 1}}\].
So, we can write the formula of equivalent weight of \[KMn{O_4}\] as,
\[{\text{Equivalent weight = }}\frac{{158}}{5}\],
\[{\text{Equivalent weight = 31}}{\text{.6}}\]\[gmo{l^{ - 1}}\].
So, we can write the Normality as,
\[{\text{Normality = }}\frac{{{\text{Weight of Solute}}}}{{{\text{Equivalent weight of Solute }} \times {\text{ Volume of solution}}}}\]
We know that the equivalent weight of solute is 31.4 \[{\text{gmol}^{ - 1}}\] and the volume of solution is given 1 liter. So,
\[1 = \frac{{{\text{Weight of KMn}}{{\text{O}}_4}}}{{31.6 \times 1}}\]
\[{\text{Weight of KMn}}{{\text{O}}_4} = 1 \times 31.6 \times 1\]
\[{\text{Weight of KMn}}{{\text{O}}_4} = 31.6gm\]
Hence we can say that we need to dissolve 31.6 g of potassium permanganate in order to prepare 1 liter 1N solution.
So, the correct answer is option (C) 31.60 g.
Note:
Do not get confused between Normality and Molarity, remember that Normality uses equivalent weight of solute and in molarity, molecular weight of solute is used. Remember that Potassium permanganate will gain 5 electrons in acidic medium and will get reduced while if the reaction is in neutral medium, then it will gain only 3 electrons in the process of reduction.
Recently Updated Pages
How many sigma and pi bonds are present in HCequiv class 11 chemistry CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Why Are Noble Gases NonReactive class 11 chemistry CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Let X and Y be the sets of all positive divisors of class 11 maths CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Let x and y be 2 real numbers which satisfy the equations class 11 maths CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Let x 4log 2sqrt 9k 1 + 7 and y dfrac132log 2sqrt5 class 11 maths CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Let x22ax+b20 and x22bx+a20 be two equations Then the class 11 maths CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Trending doubts
Fill the blanks with the suitable prepositions 1 The class 9 english CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Which are the Top 10 Largest Countries of the World?
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Write a letter to the principal requesting him to grant class 10 english CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Give 10 examples for herbs , shrubs , climbers , creepers
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Fill in the blanks A 1 lakh ten thousand B 1 million class 9 maths CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Change the following sentences into negative and interrogative class 10 english CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Difference Between Plant Cell and Animal Cell
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Differentiate between homogeneous and heterogeneous class 12 chemistry CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)