The molarity of an aqueous solution that is 20.1 % by mass calcium chloride is 2.755 M
<h2>Further Explanation:</h2><h3>Molarity </h3>
- Molarity may be defined as the concentration of a solution in moles per liter. It is calculated by dividing the number of moles of a solution, n by its volume in liters, V.
- That is; Molarity = n/V, where n is the number of moles and V is the volume in liters.
- Therefore; when given the molarity of a solution and the volume of the solution, then we can get the number of moles, by multiplying the molarity by volume;
Number of moles = Molarity x Volume
- Additionally, the number of moles of a compound or an element can also be calculated by dividing the mass of the compound by its relative molecular mass.
In this case;
Assuming the sample of solution is 100.0 g by mass
<h3>Step 1: Mass of the solvent </h3>
Mass of the solute = 20.1/100 x (100 g)
= 20.1 g
Mass of solution = mass of solute + mass of solvent
Mass of solvent = 100 g - 20.1 g
= 79.9 g
<h3>Step 2: Volume of the solvent </h3>
Density = 1.2 g/ml
But; volume = mass/density
= 78.9 g/1.2 g/ml
= 65.75 ml or 0.06575 L
<h3>Step 3: Moles of the solute, Calcium chloride </h3>
Mass of solute = 20.1 g
But 1 mole CaCl2 = 110.98 g/mol
Therefore;
Number of moles = 20.1 g/ 110.98 g/mol
= 0.1811 moles
<h3>Step 4: Molarity of CaCl2 </h3>
Molarity = Number of moles/ Volume in L
= 0.1811 moles/ 0.06575 L
= 2.755 Mole/Liter
= 2.755 M
Keywords: Molarity, Moles, Volume
<h3>Learn more about: </h3>
Level: High School
Subject: Chemistry
Chapter: Mole and stoichiometry equations
