Question

L. 14/2004- 2. Categorize the chemical used during the reaction in today's experiment. Use the Word Bank to fill in the blanks. Some answers can be used more than once. WORD BANK Starch | Na2S2O3 KI KNO3 (NH4)2S2O8 (NH4)2SO4 Two chemicals in the reaction of interest Reagent of the Clock Reaction The indicator Source of Keeps the ion concentration constant (two) BONUS (+1 Point) : THIS ANSWER IS NOT IN THE WORD BANK! Reacts with the indicator to turn the solution blue at the endpoint

Answer 1

1) two chemicals in the reaction of interest are KI and ( NH4)2_{​​​​​​}S2O8 and their reaction are

S₂O₈^2- + 2I^- $\rightarrow$. I_{​​​​​​2.} + 2SO₄^2-

Iodine form further react with thiosulphate ion

2) reagents of clock reaction are KI , ( NH4)₂S2O8 ,Na2S2O3 and starch

3) Indicator is starch which form dark blue complex with iodine

4) Source of I^{​​​​​​-} is potassium iodide ( KI)

5)Iodide ion ( I^{​​​​​-} )and thiosulphate ion ( S2O3^​​​2-​) which keeps the concentration of ions constant.

6) Iodine reacts with starch and form dark blue complex.