Question
Question: 1 M and \(2.5{\text{ L }}NaOH\) solution mixed with another 0.5 M and \(3{\text{ L }}NaOH\) solution...
1 M and 2.5 L NaOH solution mixed with another 0.5 M and 3 L NaOH solution. Then find out molarity of resultant solution:
(A) 0.80M
(B) 1.0M
(C) 0.73M
(D) 0.50M
Solution
The above question can be solved using the formula of molarity.
That is,
Molarity = Volume of solutionNo. of moles of solute
Molarity is defined as the total number of moles of solute per liter of solution.
It is represented by M that is molar.
One molar is the molarity of a solution where one gram of solute is dissolved in a liter of solution.
Equation for calculating molarity is,
M=Vn
M→ Molarity
n→ No. of moles of solute
V→ Volume of solution (in liters)
Complete step by step answer:
Now, for calculating the molarity of the resultant solution that is prepared by mixing two solutions.
We will be using the following equation.
M1V1=M2V2
For 1st solution,
M1=1M
V1=2.5L
M1=V1n1
n1=1×2.5
n1=2.5 moles
For 2nd solution,
M2=0.5M
V2=3L
M2=V2n2
n2=0.5×3
n2=1.5 moles
Total moles of NaOH in solution
n=n1+n2
n=2.5+1.5=4.0 moles
So, using the above information.
Total Molarity, M=Total VolumeTotal Moles
Total=2.5
Volume+3=5.5L
M=5.54.0
M=0.73M
So, the correct answer is Option C.
Note:
During mixing of same mixtures with different concentrations, we must remember it is the number of moles and the total quantity that remain conserved, which further are used to calculate the resultant molarity.