A 230.-mL sample of a 0.266 M MgCl 2 solution is left on a hot plate overnight;

Question

A 230.-mL sample of a 0.266 M MgCl2 solution is left on a hot plate overnight; the following morning, the solution is 2.43 M. What volume evaporated from the 0.266 M MgCl2 solution?

An average human being has about 5.0 L of blood in his or her body. if an average person were to eat 32.4 g of sugar (sucrose, C12H22O11, 342.30 g/mol), and all that sugar were dissolved into the bloodstream, how would the molarity of the blood sugar change?

Calculate the concentration of all ions presemt in each of the following solutions of strong electrolytes:

6.50 g of K3PO4 in 910.0 mL solution; Mk+ and MPO43-

Explanation / Answer

A 230.-mL sample of a 0.266 M MgCl2 solution is left on a hot plate overnight; the following morning, the solution is 2.43 M. What volume evaporated from the 0.266 M MgCl2 solution?

Solution :- Lets first calculate the final volume

M1V1 =M2V2

V2=M1V1/M2

      = 0.266 M * 230 ml / 2.43 M

      = 25.2 ml

So the amount of the solvent evaporated = 230 ml – 25.2 ml = 204.8 ml

So 204.8 ml volume of the solvent evaporated.

An average human being has about 5.0 L of blood in his or her body. if an average person were to eat 32.4 g of sugar (sucrose, C12H22O11, 342.30 g/mol), and all that sugar were dissolved into the bloodstream, how would the molarity of the blood sugar change?

Solution :- Lets first calculate the moles of the sucrose

Moles= mass/ molar mass

Moles of sucrose = 32.4 g / 342.30 g per mol = 0.0947 mol sucrose

Now lets calculate the molarity

Molarity = moles / volume in liter

                = 0.0947 mol / 5.0 L

               = 0.019 M

Therefore the molarity of the blood sugar will increase by 0.019 M

Calculate the concentration of all ions presemt in each of the following solutions of strong electrolytes:

6.50 g of K3PO4 in 910.0 mL solution; Mk+ and MPO43-

Solution :- Lets first calculate the moles of the K3PO4

Moles = mass/ molar mass

Molar mass of K3PO4 = 212.2663 g per mol

Moles of K3PO4 = 6.50 g / 212.2663 g per mol

                           = 0.03062 mol

Therefore the molarity of the K3PO4 = 0.03062 mol / 0.910 L = 0.03365 M

Mole ratio of the K3PO4 to K+ is 1 : 3 .

Therefore the molarity of the K+ = 0.03365 M K3PO4 * 3 M K+ / 1 M K3PO4 = 0.101 M K^+

Mole ratio of the K3PO4 to PO4^3- is 1 : 1

So the molarity of the PO4^3- = 0.03365 M

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