Magnesium phosphate is used to minimize the effects of vitamin E deficiency. A 3.80L solution has a magnesium ion concentration of 0.798mol/L. Calculate the mass of solute needed to prepare this solution.

1 month ago

Answered By Mandy H

Start with a dissociation equation for magnesium phosphate. Dissociation occurs when an ionic compound breaks up into its ions.

3.) number of moles = (mass of substance/ molar mass)

Manipulate the formula to find mass of substance (mass of substance = number of moles x molar mass)

mass of Mg_{3}(PO_{4})_{2} = 1.0108 mol Mg_{3}(PO_{4})_{2 }x 262.87 g/mol Mg_{3}(PO_{4})_{2 }=265.708...g Mg_{3}(PO_{4})_{2}

The final answer is the mass of magnesium phosphate required is 266 g Mg_{3}(PO_{4})_{2 }(this is considering the fact there is three significant digits from the question so the question is rounded to three digits).

1 month ago

## Answered By Mandy H

Start with a dissociation equation for magnesium phosphate. Dissociation occurs when an ionic compound breaks up into its ions.

Mg

_{3}(PO_{4})_{2 (s)}--> 3Mg^{2+}_{(aq)}+ 2PO_{4}^{3-}_{(aq)}The next step is to list all the information you know from the question:

Volume = 3.80 L

Concentration = 0.798 mol/ L Mg

^{2+}m = ? g Mg

_{3}(PO_{4})_{2 }Molar mass = 262.87 g/mol Mg

_{3}(PO_{4})_{2}There are two ways to solve this question.

The first way is to use unit analysis (arrange the question so that all the units will 'cancel' out):

3.80 L x (0.798 mol Mg

^{2+}/L) x (1 mol Mg_{3}(PO_{4})_{2}/ 3 mol Mg^{2+}) x (262.87 g/mol Mg_{3}(PO_{4})_{2}) = 265.708...g Mg_{3}(PO_{4})_{2}The second way is to use formulas:

1.) concentration = moles/ volume

Manipulate this formula to find moles (moles = concentration x volume)

moles of Mg

^{2+}= 3.80 L x 0.798 mol Mg^{2+}/L = 3.0324 mol Mg^{2+}2.) mole ratio (from the balanced chemical formula)

3.0324 mol Mg

^{2+ }x (1 mol Mg_{3}(PO_{4})_{2}/ 3 mol Mg^{2+}) = 1.0108 mol Mg_{3}(PO_{4})_{2}3.) number of moles = (mass of substance/ molar mass)

Manipulate the formula to find mass of substance (mass of substance = number of moles x molar mass)

mass of Mg

_{3}(PO_{4})_{2}= 1.0108 mol Mg_{3}(PO_{4})_{2 }x 262.87 g/mol Mg_{3}(PO_{4})_{2 }=265.708...g Mg_{3}(PO_{4})_{2}The final answer is the mass of magnesium phosphate required is 266 g Mg

_{3}(PO_{4})_{2 }(this is considering the fact there is three significant digits from the question so the question is rounded to three digits).