A 4.691-g sample of MgCl₂ is dissolved in enough water to give 750.mL of solution.What is the magnesium ion concentration in this solution? A)6.25 M B)6.57 × 10^-2M C)4.38 × 10^-2 M D)3.29 × 10^-2 M E)2.19 ×10^-2 M

Question

Quizplus · Accepted Answer

To find the magnesium ion concentration, we need to use the formula:

[Mg2+] = (moles of MgCl2) / (volume of solution in L)

First, let's calculate the number of moles of MgCl2 in the sample:

moles of MgCl2 = mass of sample / molar mass of MgCl2

The molar mass of MgCl2 is 95.21 g/mol (24.31 g/mol for Mg, plus 35.45 g/mol for Cl times 2). Therefore,

moles of MgCl2 = 4.691 g / 95.21 g/mol = 0.0493 mol

Next, let's convert the volume of the solution from mL to L:

volume of solution = 750 mL = 0.750 L

Finally, we can calculate the magnesium ion concentration:

[Mg2+] = 0.0493 mol / 0.750 L = 0.0657 M = 6.57 × 10^-3 M (in scientific notation with 2 significant figures)

A 4691-G Sample of MgCl2 Is Dissolved in Enough Water to to Give

A 4691-G Sample of MgCl₂ Is Dissolved in Enough Water to to Give