04. Titration basics

What is used to measure exactly 25cm3 of a solution?

Volumetric pipette

What is used to measure exactly 250cm3 of a solution?

Volumetric flask

How many titration repeats should be done?

2 concordant results minimum

What is the point of a rough titration?

Allows you to see end point more clearly

What is the purpose of putting a tile under the conical flask?

Allows you to see end point more clearly

What is the purpose of using a white tile under the conical flask?

Allows you to see end point more clearly

What is the purpose of adding an indicator?

Allows you to see end point more clearly

How do you make a standard solution?

1) Dissolve solid in min volume of H₂O
2) Pour into volumetric flask using funnel
3) Wash equipment into flask (beaker, funnel, stirring rod)
4) Top up to meniscus with H₂O

How would you dilute a solution before a titration for a 1:10 dilution?

1) 25cm³ from original sample using volumetric pipette
2) Add it to volumetric flask (250)
3) Top up to meniscus with H₂O

How to find a % in the following titration volumes — 5.2cm³ and 44cm³

Burette: 2 readings -> Initial and final = 0.05 and 0.05 -> Added together = 0.1
0.1 / 5.2 × 100 and 0.1 / 44 × 100

How to decrease % error?

Increasing titre -> More accurate

Lower conc. in solution or burette

When are back titrations used?

When a solid is insoluble, e.g. Gp2 carbonates, and to find % purity

When are double titrations used?

When a solution contains multiple substances e.g. carbonate/hydroxide or carbonate/hydrogen carbonate