I am unsure how to find the concentration when only % by mass is given. Any assi

Question

I am unsure how to find the concentration when only % by mass is given. Any assistance is greatly appreciated.

Question:

The concentration of the chemicals in the

dumpster are not 0.5 M, and are given as 6% by mass for sodium hypochlorite and

20.0% by mass for sodium thiosulfate. You need to figure out a way to convert

concentration by mass into molarity because that is the concentration unit you are using

in your experiment. I%u2019ll give you a hint. If a solution is 6% sodium hypochlorite by mass

that means that 6 grams out of every 100 grams of solution is sodium hypochlorite.

Explanation / Answer

6% by mass NaClO = 6 g of NaClO/100 g of solution

20.0% by mass Na2S2O3 = 20.0 g of Na2S2O3/100 g of solution

Moles of NaClO = 6 g x 1 mol/74.44 = 0.0806 moles

Moles of Na2S2O3 = 20.0 g x 1 mol/158.11 g = 0.126 moles

Molarity = moles of solute / ____L of solution = ____ moles/L

Molarity = (0.0806 moles + 0.126 moles) / ____L of solution = ____ moles/L

The total mass of the solution would be 200 g. We need the volume of the solution (in L) in order to solve for the molarity. In order to solve for the volume from the mass, you would need to be given the density of the solution. Are you given the density of the solution?   

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