Since no information was given on the volume of the bottle, I'll do the calculations using a "1-L"1-L bottle. Moreover, you don't mention what the bottle is labeled as containing "56.2 ppm"56.2 ppm. To be a little more specific, I don't know what's in the bottle to begin with.
So, I'll show you how to determine the molarity of a solution that has "56.2 ppm"56.2 ppm of "Fe"^(3+)Fe3+ ions. What ppm - parts per million - means is that you have miligrams of solute in liter of solution. A "1 ppm"1 ppm solution would mean that you have
"1 ppm" = ("1 mg")/("1 L") = ("0.001 g")/("1000 mL"1 ppm=1 mg1 L=0.001 g1000 mL
This means that a "56.2 ppm"56.2 ppm solution will have
"56.2 ppm" = ("56.2 mg")/("1 L") = ("0.0562 g")/("1000 mL")56.2 ppm=56.2 mg1 L=0.0562 g1000 mL
In order to determine molarity you need moles of solute per volume of solution. Since you know that you have "0.0562 g"0.0562 g of "Fe"^(3+)Fe3+ present, use iron's molar mass to determine how many moles you have
"0.0562 g" * ("1 mole Fe"^(3+))/("55.85 g") = "0.00101 moles Fe"^(3+)0.0562 g⋅1 mole Fe3+55.85 g=0.00101 moles Fe3+
This means that the solution's molarity is
C = n/V = ("0.00101 moles")/("1 L") = "0.00101 mol/L" = "0.00101 M"C=nV=0.00101 moles1 L=0.00101 mol/L=0.00101 M
The molarity of the solution is so small that you can express it as "mmol/L"mmol/L, or "mM"mM (milimoles per liter, or milimolar)
C = "1.01 mmol/L" = "1.01 mM"C=1.01 mmol/L=1.01 mM
