Question

Potassium bromate,${\mathrm{KBrO}}_3$is a primary standard for the generation of in acidic solution:

localid="1654933210874" ${\mathrm{BrO}}_3^{-}+5{\mathrm{Br}}^{-}+6H^{+}\rightleftharpoons 3{\mathrm{Br}}_2\left(\mathrm{aq}\right)+3H_{2}O$

Thelocalid="1654933214917" ${\mathrm{Br}}_2$can be used to analyze many unsaturated organic compounds.wasanalyzed as follows: An unknown was treated with 8 -hydroxyquinoline (oxine) atpH5to precipitate aluminum oxinate, localid="1654933218452" $\mathrm{Al}{\left({\mathrm{C}}_9{\mathrm{H}}_7\mathrm{ON}\right)}_3$The precipitate was washed, dissolved in warm HCl containing excesslocalid="1654933222732" $\mathrm{KBr}$and treated with 25.00 mLof localid="1654933226652" $0.02000{\mathrm{MKBrO}}_3$

The excesslocalid="1654933230592" ${\mathrm{Br}}_2$was reduced with Kl, which was converted intolocalid="1654933235658" ${\mathrm{l}}_{3-}^{-}$Thelocalid="1654933239460" ${\mathrm{l}}_3^{-}$ required 8.83 mLof localid="1654933242781" $0.05113{\mathrm{MNa}}_2{\mathrm{S}}_2{\mathrm{O}}_3$to reach a starch end point. How many milligrams of Al were in the unknown?

Short answer

The mass of AI is 5.729 m g.

Step-by-step solution

Calculating the mass of AI.

• Mass is a property that represents the amount of matter in a sample.Mass is expressed in grams (g) and kilograms (kg) (kg). Mass can also be defined as the property of matter that gives it the ability to resist acceleration. The more mass an object has, the more difficult it is to accelerate.
• The mass formula is as follows:

$\mathrm{Mass}=\mathrm{p}\times \mathrm{v}$

Where

$$\begin{gathered} p=density \\ v=volume \end{gathered}$$

Calculating the initial and excess moles.