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. In RP A of Dentistry, Airlangga University there were pieces of Arsenate element. A student once tried to react between Oxygen and Arsenate in acidic condition and he observed what substance would be produced. In the end of the experiment, he found molecules of Hydrogen Arsenate (HAsO2) and water. O2 + As ---> HAsO2 + H2O. Determine how many As he used!
(A)3 mole
(B) 2 mole
(C) 8 mole
(D)4 mole
(E) 6 mole

1 Jawaban

  • If want to know how many As is used in the reaction. We have to balance the reaction between O2 and As. Based on the reaction all of the elements lead to oxidation and reduction. We have to find out of each elements whether either oxidation or reduction.

    Based on the reaction the O2 leads to reduction. So, we can write an equation reaction of the O2.

    O2 → H2O

    The As leads to reduction. So, we can write the reaction of As.

    As → HAsO2

    By using half-reaction method. We can balance redox reaction.

    Red : O2 + 4H+ + 4e → 2H2O | x 3
    Oks : As + 2H2O → HAsO2 + 3H+ 3e | 4

    To make the two equal, multiply the coefficients of all species by integers producing the lowest common multiple between the half-reactions.

    4As + 3O2 + 8H2O + 12H+ + 12e- → 4HAsO2 + 6H2O + 12H+ + 12e-

    Simplify the equation. The same species on opposite sides of the arrow can be canceled.
    So, we can write the balance of whole coefficients reaction

    4As + 3O2 + 2H2O → 4HAsO2

    Based on the reaction. We know that there are 4 coefficient of As, So, in the reaction between O2 and As. It needs 4 mole of As to completely the reaction.

    Wish it hepled
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    Footnote :
    periodni.com/half-reaction_method/

    @XeMore

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