U1-1-3 - Redox Titrations

Question 1

Standard solution

Answer 1

A solution of accurately known concentration

Question 2

Procedure for preparing a standard solution:
* ________________________________
* add to volumetric flask with rinsings
* fill up to mark with water
* stopper and invert.

Answer 2

Procedure for preparing a standard solution:
* dissolve solid in small volume of water
* add to volumetric flask with rinsings
* fill up to mark with water
* stopper and invert.

Question 3

Procedure for preparing a standard solution:
* dissolve solid in small volume of water
* ____________________________________
* fill up to mark with water
* stopper and invert.

Answer 3

Procedure for preparing a standard solution:
* dissolve solid in small volume of water
* add to volumetric flask with rinsings
* fill up to mark with water
* stopper and invert.

Question 4

Procedure for preparing a standard solution:
* dissolve solid in small volume of water
* add to volumetric flask with rinsings
* ____________________________
* stopper and invert.

Answer 4

Procedure for preparing a standard solution:
* dissolve solid in small volume of water
* add to volumetric flask with rinsings
* fill up to mark with water
* stopper and invert.

Question 5

Procedure for preparing a standard solution:
* dissolve solid in small volume of water
* add to volumetric flask with rinsings
* fill up to mark with water
* ____________________________.

Answer 5

Procedure for preparing a standard solution:
* dissolve solid in small volume of water
* add to volumetric flask with rinsings
* fill up to mark with water
* stopper and invert.

Question 6

Self-indicating reaction

Answer 6

A reaction involving a reactant which changes colour to show the endpoint.

Question 7

If permanganate is used as a titrant, what is the colour change seen during the titration (as the endpoint is reached)?

Answer 7

Colourless to purple

(permanaganate ions are purple, but before the endpoint they will keep getting converted into colourless Mn²⁺ ions)

Question 8

Concordant titres

Answer 8

Titres within 0.2 cm³ of each other

(e.g. 17.2 and 17.4 are concordant)

Question 9

Where do n₁ and n₂ come from?

Answer 9

Balanced equation - NOT calculated using n=cV!

E.g. in the equation shown, n₁ (Fe²⁺) = 6, n₂ (Cr₂O₇^2-) = 1

Question 10

Suggest an improvement

Answer 10

Read burette at eye level

Use a white tile

Remove funnel from burette

Question 11

Suggest what you would use to accurately measure 10 cm³ of solution

Answer 11

Pipette

Question 12

Procedure to prepare a burette for titration:
* ____________________________
* remove filter funnel
* open tap to release air bubbles
* read scale from bottom of meniscus.

Answer 12

Procedure to prepare a burette for titration:
* rinse with solution which will be added to the burette (NOT water)
* remove filter funnel
* open tap to release air bubbles
* read scale from bottom of meniscus.

Question 13

Procedure to prepare a burette for titration:
* rinse with solution which will be added to the burette (NOT water)
* remove ____________
* open tap to release air bubbles
* read scale from bottom of meniscus.

Answer 13

Procedure to prepare a burette for titration:
* rinse with solution which will be added to the burette (NOT water)
* remove filter funnel
* open tap to release air bubbles
* read scale from bottom of meniscus.

Question 14

Procedure to prepare a burette for titration:
* rinse with solution which will be added to the burette (NOT water)
* remove filter funnel
* open tap to ____________________
* read scale from bottom of meniscus.

Answer 14

Procedure to prepare a burette for titration:
* rinse with solution which will be added to the burette (NOT water)
* remove filter funnel
* open tap to release air bubbles
* read scale from bottom of meniscus.

Question 15

Procedure to prepare a burette for titration:
* rinse with solution which will be added to the burette (NOT water)
* remove filter funnel
* open tap to release air bubbles
* read scale from _______________________.

Answer 15

Procedure to prepare a burette for titration:
* rinse with solution which will be added to the burette (NOT water)
* remove filter funnel
* open tap to release air bubbles
* read scale from bottom of meniscus.

Question 16

What indicator should be used in a titration involving iodine?

Answer 16

Starch

turns blue-black in the presence of iodine

Question 17

Procedure to prepare a pipette for measurement:
* rinse pipette with ________________
* fill to above volume mark and run down to mark
* read scale from bottom of meniscus.

Answer 17

Procedure to prepare a pipette for measurement:
* rinse pipette with solution to be measured
* fill to above volume mark and run down to mark
* read scale from bottom of meniscus.

Question 18

Procedure to prepare a pipette for measurement:
* rinse pipette with solution to be measured
* fill to ________________ and run down to ________
* read scale from bottom of meniscus.

Answer 18

Procedure to prepare a pipette for measurement:
* rinse pipette with solution to be measured
* fill to above volume mark and run down to mark
* read scale from bottom of meniscus.