Chemistry...Empirical formula problem.?

What is the empirical formula (lowest whole number ratio) of the compounds below?

22.1% aluminum, 25.4% phosphorous, 52.5% oxygen

can you please give a little explanation on each step? i'm really lost. thank you :]

Comments

  • % by weight is the amount of grams of stuff ...

    use molar mass to find moles:

    22.1g aluminum, @ 27 g/mol = 0.82 moles of Al

    25.4g phosphorous @ 31 g/mol = 0.82 mol P

    52.5g oxygen @ 16 g/mol = 3.28 mol O

    ratio the moles by dividing by the smallest moles

    0.82 mol Al / 0.82 = 1 mol Al

    0.82 mol P / 0.82 = 1 mol P

    3.28 mol O / 0.82 = 4 mol O

    that gives your empirical formula:

    AlPO4

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