Define Molarity Write the Expression to
Calculate the Molarity of solution for the given mass solute and volume of the solution (2m)
Answers
Answer:
Molarity (M) is the amount of a substance in a certain volume of solution. Molarity is defined as the moles of a solute per liters of a solution. Molarity is also known as the molar concentration of a solution.
Let's consider a solution made by dissolving 2.355\,\text g2.355g2, point, 355, start text, g, end text of sulfuric acid, \text H_2 \text {SO}_4H
2
SO
4
start text, H, end text, start subscript, 2, end subscript, start text, S, O, end text, start subscript, 4, end subscript, in water. The total volume of the solution is 50.0\,\text{mL}50.0mL50, point, 0, start text, m, L, end text. What is the molar concentration of sulfuric acid, [\text H_2 \text{SO}_4][H
2
SO
4
]open bracket, start text, H, end text, start subscript, 2, end subscript, start text, S, O, end text, start subscript, 4, end subscript, close bracket?
To find [\text H_2 \text{SO}_4][H
2
SO
4
]open bracket, start text, H, end text, start subscript, 2, end subscript, start text, S, O, end text, start subscript, 4, end subscript, close bracket we need to find out how many moles of sulfuric acid are in solution. We can convert the mass of the solute to moles using the molecular weight of sulfuric acid, 98.08\,\dfrac{\text g}{\text {mol}}98.08
mol
g
98, point, 08, start fraction, start text, g, end text, divided by, start text, m, o, l, end text, end fraction:
\text{mol H}_2\text{SO}_4=2.355\,\cancel{\text g} {\text{ H}_2\text{SO}_4}\times \dfrac{1\,\text {mol}} {98.08\,\cancel{\text {g}}} = 0.02401\,\text{mol H}_2\text{SO}_4mol H
2
SO
4
=2.355
g
H
2
SO
4
×
98.08
g
1mol
=0.02401mol h2So4
We can now plug in the moles of sulfuric acid and total volume of solution in the molarity equation to calculate the molar concentration of sulfuric acid:
\begin{aligned} [\text H_2 \text{SO}_4]&= \dfrac{\text{mol solute}}{\text{L of solution}}\\ \\ &=\dfrac{0.02401\,\text{mol}}{0.050\,\text L}\\ \\ &=0.48 \,\text M\end{aligned}
[H
2
SO
4
]
=
L of solution
mol solute
=
0.050L
0.02401mol
=0.48M
Concept check: What is the molar concentration of \text H^+H
+
start text, H, end text, start superscript, plus, end superscript ions in a 4.8\,\text {M H}_2 \text{SO}_44.8M H
2
SO
4
4, point, 8, start text, M, space, H, end text, start subscript, 2, end subscript, start text, S, O, end text, start subscript, 4, end subscript solution?