Question

Consider the following reaction in aqueous solution:

      5 Br⁻(aq) + BrO₃⁻(aq) + 6 H⁺(aq) ---> 3 Br₂(aq) + 3 H₂O(l)

i)    The equation that relates the rate expressions for this reaction in terms of the disappearance of Br⁻, BrO₃⁻ and the formation of Br₂ and H₂O is (Choose the correct letter.):     
NOTE: { } is being used to represent the molar concentration.

A.   R = -1/5{ Δ Br - }/ Δ t = -1/1{ Δ BrO 3- }/ Δ t = - 1/6{ Δ H + }/ Δ t = -1/3{ Δ Br 2 }/ Δ t

B.   R = +1/5{ Δ Br - }/ Δ t = +1/1{ Δ BrO 3- }/ Δ t = -1/3{ Δ Br 2 }/ Δ t = +1/3{ Δ H 2 O}/ Δ t

C.   R = -1/5{ Δ Br - }/ Δ t = -1/1{ Δ BrO 3- }/ Δ t = -1/6{ Δ H + }/ Δ t = +1/3{ Δ H 2 O}/ Δ t

D.   R = -1/5{ Δ Br - }/ Δ t = -1/1{ Δ BrO 3- }/ Δ t = +1/3{ Δ Br 2 }/ Δ t   = +1/3{ Δ H 2 O}/ Δ t

E.    R = -1/1{ Δ Br - }/ Δ t = -1/5{ Δ BrO 3- }/ Δ t = +1/3{ Δ Br 2 }/ Δ t = +1/3{ Δ H 2 O}/ Δ t

If the rate of disappearance of Br ^– ( aq ) at a particular moment during the reaction is 3.5 x 10 ^–4M s ^–1 ,

( NOTE : For scientific notation, use "E" or "e" to replace "x 10" & do NOT leave any space between the numbers and letter, e.g., 1.2E3 or 1.1e-4.)

ii) what is the rate of appearance of Br ₂ ( aq ) at that moment? (Give answer in scientific notation):  M.s ^-1

iii) calculate the overall or average rate of the reaction. (Give answer in scientific notation):  M.s ^-1

^{I have found parts i and ii but am struggling with part iii. Thanks!}

Answer 1