Question

A chemist makes up a solution by dissolving 39.0 g of Mg(NO3)2 in enough water to produce a final solution volume of 257 mL. To calculate the molarity of the solution, what additional information is needed

Answer 1

`M=1.02M`

Step-by-step explanation:

Hello.

In this case, since the molarity of a solution is computed as the moles of solute over volume of solution:

`M=(n_(solute))/(V)`

Since the volume of the solution is 257 mL or also 0.257 L, we compute the moles of solute, which is magnesium nitrate (molar mass = 148.3 g/mol), as shown below:

`n_(solute)=39.0gMg(NO_3)_2*(1molMg(NO_3)_2)/(148.3 gMg(NO_3)_2)=0.263molMg(NO_3)_2`

Thus, the required molarity turns out:

`M=(0.263molMg(NO_3)_2 )/(0.257L)\\ \\M=1.02M`

Best regards.