Question

9) A solution contains 20g of common salt in 120g of water. Calculate the concentration
in terms of mass-by-mass percentage of the solution.​

Answer 1

$\Large{ \red{ \boxed{ \tt{ \purple{Concentration \: of \: solution}}}}}$

✦Mass by mass percentage :

The mass of solute in grams dissolved in 100 g of the solution. Generally this method is used, when the concentration of solution is asked, but not mentioned that whether it is Volume by Volume percentage etc. Ot is calculated as,

${ \star \: {\boxed{ \red{ \rm{Mass \: by \: Mass \: \% = \frac{mass \: of \: solute(g)}{mass \: of \: solution(g)} \times 100}}}}}$

⚠️ Always remember that, mass of solute is divided by mass of solution not solvent. Mass of solution is mass of solute + mass of solvent.

By using formula,

$\large{ \circ{ \rm {Mass \: of \: solute = 20g}}} \\ \\ \large{ \rm{ \circ {Mass \: of \: solution = 20g + 120g = 140g }}} \\ \\ \large{ \rm{ \rightarrow \: Mass \: by \: Mass\% = \frac{20}{140} \times 100}} \\ \\ \large{ \rm{ \rightarrow \: Mass \: by \: Mass\% = \cancel{\frac{2000}{140}\%}}} \\ \\ \large{ \rm{ \rightarrow \: Mass \: by \: Mass\% \: \approx \: \boxed{ \purple{ \rm{14.285}}}}} \\ \\ \large{ \therefore{ \underline{ \rm{ \underline{ \green{Hence, \: solved \: \dag}}}}}}$

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$\Large{\red{\boxed{\tt{\purple{Let's\: concentrate \:more...}}}}}$

✦ Mass by Volume percentage:

The mass of the solute in grams dissolved in 100 ml of solution is the way of finding the concentration in terms of mass and volume of solute and solution respectively.

${ \star \: {\boxed{ \red{ \rm{Mass \: by \: Volume\: \% = \frac{Mass \: of \: solute(g)}{Volume \: of \: solution(ml)} \times 100}}}}}$

✦Volume by Volume percentage:

The volume of solute in ml dissolved in 100 ml of solution is the way of finding concentration in terms of volume of solute and solvent.

${ \star \: {\boxed{ \red{ \rm{Volume \: by \: Volume \: \% = \frac{Volume\: of \: solute(ml)}{Volume \: of \: solution(ml)} \times 100}}}}}$

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