I suppose we are to assume that the volumes are additive.
M1V1 = M2V2
0.150*1.5 = M2*(3.5+1.5)
M2 = 0.045M
Another way.
You start with 1.5 mL and end up with 5.0 mL (if the solutions are additive) so 0.150M x (1.5/5.0) = 0.045M
M1V1=M2V2
M1= 0.150
V1= 1.5mL
M2= 3.5?
M1V1 = M2V2
0.150*1.5 = M2*(3.5+1.5)
M2 = 0.045M
Another way.
You start with 1.5 mL and end up with 5.0 mL (if the solutions are additive) so 0.150M x (1.5/5.0) = 0.045M
In this case, M1 = 0.150 M (the initial concentration of the CoCl2 solution) and V1 = 1.5 mL (the initial volume).
To find the final volume, we need to take into account that 3.5 mL of distilled water is added to the initial solution. Therefore, the final volume (V2) will be the sum of the initial volume and the volume of water added, which is 1.5 mL + 3.5 mL = 5.0 mL.
Now, we can rearrange the formula to solve for M2:
M2 = (M1 * V1) / V2
Substituting the values we have:
M2 = (0.150 M * 1.5 mL) / 5.0 mL
Multiply 0.150 M by 1.5 mL:
M2 = 0.225 / 5.0 mL
Divide 0.225 by 5.0 mL:
M2 = 0.045 M
Therefore, the concentration of the resulting solution is 0.045 M.