Question

if the formula weight of $ {H_2}S{O_4} $ is $ 98 $ , then the amount of acid present in $ 400ml $ of $ 0.1 $ molar solution of acid will be:
 $ A)2.45g \\
  B)3.92g \\
  C)4.90g \\
  D)9.80g \\ $

Answer 1

Hint: Molarity indicates the number of moles of solute per liter of solution and is one of the most common units used to measure the concentration of a solution. Molarity can be used to calculate the volume of solvent or the amount of solute.

Complete answer:
Molar concentration is a measure of the concentration of a chemical species, in particular of a solute in a solution, in terms of amount of substance per unit volume of solution. Molarity is most commonly expressed in units of moles of solute per litre of solution. For use in broader applications, it is defined as the amount of substance of solute per unit volume of solution, or per unit volume available to the species.
 $ M = \dfrac{n}{v} $
Where, $ M = molar\;concentration $
 $ n = moles\;of\;solute $
 $ v = volume\;of\;solution $
Molarity = $ \dfrac{{weight}}{{molecular\;weight}} \times \dfrac{{1000}}{{Vml}} $
 $ 0.1 = \dfrac{W}{{98}} \times \dfrac{{1000}}{{400}} $
 $ W = \dfrac{{98 \times 4 \times 0.1}}{{10}} $
 $ = 3.92g $
So, the correct answer is $ B)3.92g $ .

Additional Information:
 $ - $ It is easy and convenient to use because the solute may be measured in grams, converted into moles, and mixed with a volume.
 $ - $ The sum of the molar concentrations is the total molar concentration. This permits calculations of density and ionic strength.
 $ - $ The disadvantage of molarity is that it changes according to temperature. This is because the volume of a liquid is affected by temperature

Note:
The utilization of molar concentration is regularly not advantageous on the grounds that the volume of most arrangements somewhat relies upon temperature because of thermal extension. This issue is normally settled by presenting temperature adjustment factors, or by utilizing a temperature-autonomous proportion of focus, for example, molality.