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Stoichiometry question?

One method of producing aluminum bromide is shown in the following unbalanced reaction. What mass of aluminum bromide can be produced by the reaction of sufficient aluminum sulfate with 8.75g of ammonium bromide?

Al2(SO4)3 + NH4Br --> AlBr3 + (NH4)2SO4

3 Answers

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  • 9 years ago
    Favorite Answer

    Write a properly balanced equation:

    Al2(SO4)3 + 6 NH4Br = 2 AlBr3 + 3 (NH4)2SO4

    6mol NH4Br will produce 2 mol AlBr3

    Molar mass NH4Br = 97.94g/mol

    8.75g NH4Br = 8.75/97.94 = 0.0893 mol NH4Br

    From the balanced equation this will produce 0.0893*2/6 = 0.0298 mol AlBr3

    Molar mass AlBr3 = 266.7g/mol

    0.0298 mol = 0.0298*266.7 = 7.94 g AlBr3 produced.

  • Gianni
    Lv 7
    9 years ago

    The balanced equation is:

    Al2(SO4)3 + 6NH4Br --> 2AlBr3 + 3(NH4)2SO4

    Now, you've got 8,75g of ammonium bromide. which corresponds to:

    n(NH4Br) = 8,75g / 97,904g/mol = 0,0894mol

    For each mole of NH4Br, you have a third of moles of AlBr3 ( ratio 6:3 ), then:

    n(AlBr3) = n(NH4Br) = 0,0894mol * 1/3 = 0,0298mol ----->

    ------> m(AlBr3) = 0,0298mol * 266,7g/mol = 7,95g

    Bye Bye :)

  • 9 years ago

    Bal. Rxn.: Al2(SO4)3 + 6 NH4Br --> 2 AlBr3 + 3 (NH4)2SO4

    2 moles of AlBr3 are formed per 6 moles of NH4Br (1:2)

    moles NH4Br: 8.75 g/molec wt NH4Br

    ? moles NH4Br x 1/2 x molec. wt AlBr3= answer

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