Write the balanced equations for these reactions: 1 mL of a 0.1 M aqueous TiOSO4

ID: 512298 • Letter: W

Question

Write the balanced equations for these reactions:

1 mL of a 0.1 M aqueous TiOSO4 was added to 5 test tubes. The following proceducre depicts the reactions that occured in each test tube:

Test Tube 1: "Blank" Leave as is (clear, colorless liquid)

Test Tube 2: Added 0.5 mL of HCl, noted any observations:

solution turned yellow

Test Tube 3: Heated solution in water bath (80oC); noted any observations:

no change, however solution did express odor when heating.

Test Tube 4: Added a small amount of Zn dust; note any observations.

Instantly turned dark, almost black and precipitated. After a while, the solution turned fully black. Some bubbling was observed

Test Tube 5: Filtered solution from test tube 4 into new test tube and added 0.5 mL of concentrated HCl; noted any observations:

At first there was no change in the solution, however as time progressed, the solution became lighter and eventually cleared.

Why is foam formed upon HCl addition?

Reactions of TiOSO4

Test tube 1 : original color - colorless

Test tube 2 : added HCl, turns yellow due to the reaction,

TiOSO4 + 2HCl --> TiOCl2 + H2SO4

Test tube 3 : heated, no change

TiOSO4 hydrolyzed to TiO2.nH2O

Test tube 4 : added Zn dust

TiOSO4 + Zn + H2O ---> TiO2 + ZnSO4 + H2

it gives black color due to excess Zn

Test tube 5 : Added HCl to the filtrate from test tube 4,

Zn + 2HCl --> ZnCl2 + H2

leftover Zn reacted with HCl

foam is formed due to formation of H2 gas along with precipitate upon addition of HCl

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