Yes, %M = (5.65/12.47)*100 = ? about 45% but you need a more accurate number than that.
Then what do you do to identify the metal. I will use estimates BUT you must get accurate numbers yourself.
%Cl then must be 100%-45.?% = about 55%. Be sure and get good numbers to at least 3 places.
Here is how you would do it IF you had the atomic mass of the metal. You don't so we will call it x.
mols M = about (45/x) = y
mols Cl = about (55/35.45) = about 1.5. You KNOW the formula is MCl2; therefore, that 1.5 number for the mols Cl must be twice the y number so y must be about 0.75. That means x = about (45/0.75) = about 60 or so
You can look that up on the periodic table. I stress the accuracy of your numbers because it will be difficult to know the difference between two possible elements. The metal is between Fe and Cu on the periodic table.
So I have to find the % by mass of an unknown metal that reacted with HCl to create MCl2 (with the M being unknown). Then I need to determine identity of the missing metal.
I know that the final mass of the compound MCl2 is 12.47g and that the original mass of the metal M before the reactions was 5.65g.
Also, I'm told the reaction went to 100% completion.
I'm stuck because I'm not sure if I can assume that since all of the metal reacted that I can divide 5.65g by 12.47g to find the % by mass of the unknown metal in the compound.
Can I do that or are there other steps that I need to do first?
If so, how? I can't think of how else to use those two values other than subtracting or dividing them to find the percentages since I don't have the molar mass of the compound.
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Thanks for the clarification and confirming my assumption. I'll be sure to use accurate values in the calculation.
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