Question

Concentration is measured in moles per litre. Explain.

Answer 1

The concentration is measured in many variable units based on some parameters and definition, one of them is moles per litre.

Complete step by step solution:
Let us first discuss concentration and its units.
Concentration-
The concentration is the measure of solute present in the required amount of solvent to form a solution.
Units of concentration-
1. Concentration are at times expressed in relative units i.e. percentages-
a. Mass percent
b. Volume percent
c. Mass/Volume percent
2. Concentration units when solutions are dilute-
a. Parts per million
b. Parts per billion
c. Parts per trillion
3. Concentration based on moles-
a. Mole fraction
b. Mole percent
c. Molarity
d. Molality
Now, concentrating on the given condition,
The concentration measured in moles per litre is known as molarity. It is given as,
$M=\dfrac{n}{V}$
where,
M = molarity of the solution
n = number of moles of solute, which is given as the ratio of given mass and molar mass of solute;
$n=\dfrac{{{m}_{given}}}{{{m}_{molar}}}$
V = volume of solution in litres
Molarity is the most common unit of concentration used to measure the concentration of the solution. This can also be used to calculate volume of solution and amount of solute.

Note: The most commonly used method is always practised. But that does not mean we don’t have other methods. Concentration is calculated in many ways as discussed above.