Question

What molarity is $10\%$ of $NaOH$ ?

Answer 1

Hint : Molarity or molar concentration is the number of moles of solute per litre of solution, which can be calculated by a formula. The chemical in the mixture that is present in the largest amount is called the solvent, and the other components are called solutes.

Complete Step By Step Answer:
The formula for calculating molarity is $Molarity = \dfrac{{mo{l_{}}solute}}{{{L_{}}o{f_{}}solution}}$
Molarity has units of $\dfrac{{mol}}{{liter}}$ , which can be abbreviated as molar or M (pronounced molar).
$10\% of$ $NaOH$ means $100gm$ of solution present in $10gm$ of $NaOH$ .
Here, number of moles of $NaOH$ = $\dfrac{{10}}{{40}} = \dfrac{1}{4}$
Now, we know the density of water is $1g/ml$ and density= $\dfrac{{mas{s_{}}o{f_{}}solution}}{{Volume}}$
We can convert to density by multiplying the number of moles by the molecular mass of the compound. Convert density to molarity by converting to frames per liter and dividing by the molecular mass of the compound in grams.
The, volume= $\dfrac{{100}}{1} = 100ml$
Molarity= \dfrac{{mole}}{{Litre}} = \dfrac{1}{{{\raise0.7ex\hbox{ {4 \times 1000} } \\!\mathord{\left/ {\vphantom {{4 \times 1000} {100}}}\right.} \\!\lower0.7ex\hbox{ {100} }}}}
= 0.25{\raise0.7ex\hbox{ {mol} } \\!\mathord{\left/ {\vphantom {{mol} L}}\right.} \\!\lower0.7ex\hbox{ L }} or M
Molarity can be used to calculate the volume of solvent or the amount of solute. The relationship between two solutions with the same amount of moles of solute can be represented by the formula ${c_1}{V_1} = {c_2}{V_2}$ , where c is concentration and V is volume. ${c_1}{V_1} = {c_2}{V_2}$ .

Note :
Molar concentration can be used to convert between the mass or moles of solute and the volume of the solution. If you know the grams of the chemical, convert to the moles of the compound by using the molar mass of the compound.
If you are given $ml$ , convert to liter; remember the conversion factor: $1000ml = 1L$
In a laboratory situation, a chemist must frequently prepare a given volume of solution of a known molarity. The task is to calculate the mass of the solute that is necessary.