Question

$50\,cm^3$ of $0.04 \,M \,K_2 Cr_2 O_7$ in acidic medium oxidizes a sample of $H_2S$ gas to sulphur. Volume of $0.03\, M$ $KMnO_4$ required to oxidize the same amount of $H_2S$ gas to sulphur, in acidic medium is

• A. $80\,cm^3$
• B. $120\,cm^3$
• C. $60\,cm^3$
• D. $90\,cm^3$

Answer 1

The Correct Option is A

$\because \frac{\text { Normality }}{\text { Molarity }}=\frac{\text { Molecular weight }}{\text { Equivalent weight }}$

For $K _{2} Cr _{2} O _{7}$
$\therefore \frac{N_{1}}{0.04} =\frac{294}{49}$
$N_{1} =\frac{294}{49} \times 0.04=0.24$

For $KMnO _{4}, \frac{N_{2}}{0.03} =\frac{158}{31.6}$
$N_{2} =\frac{158}{31.6} \times 0.03=0.15$

Now, from normality equation

$N_{1} V_{1}=N_{2} V_{2}$
$\Rightarrow 0.24 \times 50=0.15 \times V_{2}$
$V_{2}=\frac{0.25 \times 50}{0.15}=80\, cm ^{3}$

Answer 2

Ans. Normality is defined as the number of grams that is equal to the solute mixed in per liter of the solution. This method is generally used to express the concentration of the solute dissolved in a solution. The formula for normality is given by,

N = Weight of Solute in gm. / Equivalent Weight × Volume in ltr.

Concentration is the amount of solute dissolved in the given amount of solution. The SI unit for Normality is gram per liter. It can be used as a reactive species in the solution. It is also used for the quantitative measurement of the substance during the chemical process.

The concentration of the provided solution during the specific chemical process is determined by normality. To put it another way, we may say that normality is the number of grams of solute equivalents present in each liter of solution. The letter 'N' stands for normality. The gram/liter is the SI unit used internationally. A concentration equivalent is another name for this. 

The characteristics of a solution's normality might include several things.

• It is primarily used to gauge the solution's concentration.
• Normality is employed in several processes, such as the precipitation reaction. Finding out how many ions are precipitated throughout the reaction is the key goal here.
• Redox reactions employ the procedure. It is measured how many electrons there are.

The formula of Normality is used to measure the concentration of the given solution. 

When all the steps are followed perfectly then the formula for Normality is obtained. The formula is given below. 

Normality = Number of Gram Equivalents / Volume of Solution in liters

Therefore, 

No.of Equivalent Gram = Weight of Solute / Equivalent Weight of Solute

Hence, 

N = Weight of Solute in gm. / Equivalent Weight × Volume in ltr.

The normality can be measured by using the value of the Molarity of the solution. Therefore, the formula will be written as. 

Normality (N) = Molarity × Molar mass / Equivalent mass

Normality (N) = Molarity × Basicity = Molarity × Acidity