Question

The amount of NaOH in gms in 250cm3 of a 0.100M NaOH solution would be
A . 4 gm
B . 2 gm
C . 1 gm
D . 2.5 gm

Answer 1

Hint: In this question we have to use the concept of molarity and find out the grams of solute present in the given volume of 0.1M concentration. We must first calculate the amount of moles by dividing the weight of compound NaOH by its molecular weight. With this knowledge, the molarity of the solution in moles per litre volume can subsequently be calculated.

Complete answer:Moles per litre of a solution, also known as moles per litre of a solution, is a measure of a solution's molar concentration or molarity. It is one of the concentration units that are most frequently used, and the letter M stands in for it.
The formula for it is:
$Molarity=\dfrac{moles\text{ }of\text{ }solute}{volume\text{ }of\text{ }solution\text{ }in\text{ }litres}$
The SI unit for molarity is mol/L.
In the given question, the solute is NaOH.
Molar mass of NaOH = molar mass of Na + molar mass of O + molar mass of H = 23+16+1 = 40g/mol
$Molarity=\dfrac{moles\text{ }of\text{ }solute}{volume\text{ }of\text{ }solution\text{ }in\text{ }litres}$
$0.1=\dfrac{{{w}_{NaOH}}\times 4}{40\times 1}=1gm$
Therefore, the weight of NaOH is 1gm

The correct answer is C.

Note: Molality, normality, and molarity may all be used interchangeably. Molality is denoted by the letter "m," as opposed to molarity, which is symbolized by the letter "M." The number of moles of solute per kilogram of solvent is used to determine the molality of any solution. It may be stated as follows:
$Molality=\dfrac{moles\text{ }per\text{ }solute\left( mol \right)}{weight\text{ }of\text{ }solvent\text{ }in\text{ }kg}$
It has the SI unit mol/kg.
The term "normality" refers to the quantity of solute in a solution measured in grams or moles per litre. It is commonly referred to as a solution's equivalent concentration and is denoted by the letter "N". N or equivalents/Litre serve as the units of normality.