Question

How many grams of silver nitrate are needed to prepare 250mL of standard 0.100M silver nitrate solution?

Answer 1

Hint: Silver nitrate is considered as a salt which has no colour, that is it is colourless white crystalline salt. But when it is exposed to light it changes into a black colour substance. It tends to decompose on heating and give the products as silver, nitrogen dioxide and oxygen. It has high solubility in water and tends to get soluble in ethanol and acetone.

Complete step by step answer:
Here in 0.100M the ‘M’ represents the molarity. So molarity is defined as the number of moles of the solute which are present in per litre of solution. The formula for molarity is the following:
Molarity $$ = \dfrac{{moles}}{{volume \; of \; solution(L)}}$$
The values given in the question are:
Molarity = 0.100M
Volume = 250mL = 0.25L

Substituting the values in the formula we get,
$ \Rightarrow 0.100 = \dfrac{{moles}}{{0.25}}$
$ \Rightarrow Moles = 0.100 \times 0.25$
$ \Rightarrow Moles = 0.025 moles.$
To calculate the grams of silver nitrate from its moles we will use the following formula
Moles = $$\dfrac{{mass}}{{molecular \; mass}}$$
Moles = 0.025
Now we will calculate the molecular mass of silver nitrate $$AgN{O_3}$$
 $AgN{O_3} = 108+14+3(16)=170gram mo{l^{ - 1}}$
Substituting the values in the formula we get,
$ \Rightarrow 0.025 = \dfrac{{mass}}{{170}}$
$ \Rightarrow Mass = 170 \times 0.025$
$ \Rightarrow Mass = 4.25 grams.$

So the mass of silver nitrate needed is 4.25 grams.

Note: The molarity of the solution is affected by the changes in the physical properties of the system such as pressure, temperature. The one molar is defined as the molarity of the solution in which one gram of solution is being dissolved in one litre of the solution. The total volume of the solution has been taken because both the solute and solvent blend to form the solution.