Question

Calculate the molarity of $98\% $${H_2}S{O_4}$(d$ = 1.8g/ml$) by weight.

Answer 1

Hint: The concentration of a solution is commonly expressed by its molarity, defined as the amount of dissolved substance per unit volume of solution, for which the unit used in moles per litre. Molarity can also be used to calculate the volume of solvent or the amount of solute in a given solution.
The units of molarity are M or \[mol/L\]. A $1$ M solution is said to be “one molar.
Molarity equation ,M $ = $moles solute $/$liters solution

Complete step by step answer:
We can say that $98$ g of the sulphuric acid is present in the $100$ g of the solution.
Molar Mass of sulphuric acid $ = $ $98$ g/mole.
∵ No. of moles \[ = {\text{ }}Mass/Molar Mass\]
∴ No. of moles \[ = {\text{ }}98/98\]
\[ = {\text{ }}1\]mole.
The Molar Mass of a molecule can be calculated from its molecular formula by taking the sum of atomic masses of all the elements present in it. Molar mass is calculated in grams. Mass in grams is the given mass of the substance in the solution
Also, the Density of the solution
∵ Density \[ = {\text{ }}Mass/Volume.\]
∴ Volume \[ = {\text{ }}100/1.8\]

\[ = {\text{ }}0.0556{\text{ }}L.\]
Now, Using the Formula,
Molarity $ = $ No. of moles of solute$/$Volume of the solutions in liter.
\[ = {\text{ }}1/0.0556\]
\[ = {\text{ }}17.98{\text{ }}M\]
Hence, the molarity of the solution is \[ = {\text{ }}17.98{\text{ }}M\].

Note: Number of moles$ = $mass in grams/molar mass
-One mole of a substance is equal to $6.022 \times {10^{23}}$ units of that substance (such as atoms, molecules or, ions)
-The number $6.022 \times {10^{23}}$ is known as Avogadro’s number or Avogadro’s constant.
-The mole is widely used in chemistry as a convenient way to express amounts of reactants and products of chemical reactions.
-The relationship between any two solutions with the same amount of moles of solute can even be expressed by the formula\[{c_1}{V_1}\; = {\text{ }}{c_2}{V_2}\], where c is the concentration and V is the volume.