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How many grams of NaCl (MW=58.4 g/mol) are contained in 350.0 mL of a 0.250 M so

ID: 785006 • Letter: H

Question

How many grams of NaCl (MW=58.4 g/mol) are contained in 350.0 mL of a 0.250 M solution of sodium chloride?

                5.11 g

                14.6 g

                41.7 g

                81.8 g

                87.5 g

If 5.15 g FeCl3 is dissolved in enough water to make exactly 150.0 mL of solution, what is the molar concentration of chloride ion? The formula weight of FeCl3 is 162.4 g/mol) and the solution has a density of 1.2 g/mL.

                0.103 M

                0.212 M

                0.578 M

                0.635 M

                16.7 M

If 5.00 mL of 0.314 M KOH is diluted to exactly 125 mL with water, what is the concentration of the resulting solution?

                0.127 M

                0.281 M

                7.85 M

                1.26 x 10-2 M

                5.02 x 10-4 M

How many grams of NaCl (MW=58.4 g/mol) are contained in 350.0 mL of a 0.250 M solution of sodium chloride? If 5.15 g FeCl3 is dissolved in enough water to make exactly 150.0 mL of solution, what is the molar concentration of chloride ion? The formula weight of FeCl3 is 162.4 g/mol) and the solution has a density of 1.2 g/mL. If 5.00 mL of 0.314 M KOH is diluted to exactly 125 mL with water, what is the concentration of the resulting solution?

Explanation / Answer

1)Moles = Molarity x Volume ( in Liters)


Moles = 0.250 x 0.350 L = 0.0875


Mass = moles x molar mass = 0.0875 mol x 58.4428 g/mol =5.11 g


2)Molar concentration = moles of solute/liters of solution


First change 5.15g FeCl3 to moles FeCl3 = 0.0318mol FeCl3


Figure out the balanced eqn for dissolved FeCl3


FeCl3 ? Fe+ + 3Cl-


Using the balanced eqn, find moles of Cl-


(0.0318mol FeCl3)(3mol Cl- / 1mol FeCl3) = 0.0954mol Cl-


Now use moles of Cl- divided by the volume in liters of solution to find molar concentration


(0.0954mol/.150L) = 0.635M



3)MV=MV

(0.314)(5) =M(125)

M=0.01256 M = 1.26 * 10^-2 M

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