Question

How do you calculate the mass of lead(II) nitrate, $Pb{{(N{{O}_{3}})}_{2}}$ , necessary to make 50 mL of a 0.100M solution?

Answer 1

Hint To solve this question, first we have to understand the term molarity. Molarity is represented by capital “M”. Molar solution is also known as molarity.

Complete step by step solution:
Molar solution is also known as molarity. Molarity is one of the standard expressions of solution concentration. The molar solution used the gram molecular weight of a solute in calculating molar concentration present in per litre of the solution. Molarity is denoted by the symbol M. The formula of molarity is given below:
molarity = $\dfrac{\text{moles of solute}}{volume\text{ of solution in liter}}$
given in the question:
volume = 50mL = 0.05L
now, 0.1M $=\dfrac{n}{0.05L}$
where, n is the number of moles of $Pb{{(N{{O}_{3}})}_{2}}$
so, n =0.005 moles
Number of mol is calculated by ratio of given mass to the molar mass.
Number of mol = $\dfrac{\text{given mass}}{\text{molar mass}}$
Molar mass of $Pb{{(N{{O}_{3}})}_{2}}$= 331 g/mol
Given mass = $331\times 0.005=1.655g$
Hence, the mass of lead nitrate is = 1.655g.

Additional information:
1 mole= $6.022X{{10}^{23}}$ particle or atoms or molecules or electrons or protons etc. The number of the constituent particles of atoms such as molecules or atoms or ions present in a given sample is related with the mass of the substance present in the sample using Avogadro's number. The SI unit of Avogadro’s number is inverse of mole i.e. $mol{{e}^{-1}}$

Note: Do not get confused between molarity and molality. Molality is defined as the number of moles of solute which is dissolved in one kilogram of solvent. The term molality is denoted by the symbol m. whereas, molarity is the molar solution used the gram molecular weight of a solute in calculating molar concentration present in per litre of the solution. Molarity is denoted by the symbol M.