Chem prac skills: titration Flashcards
(15 cards)
Exothermic or endothermic between SA and SB?
exothermic — heat released when water is formed
Accuracy
- rinse to prevent dilution/contamination
- view at eye level (avoid parallax error)
- zero the scale
- one drop, and swirl
- white tile
Precision
- white tile
- wash sides of conical flask when titrant added
- take multiple values and average them
Improvements
Prec: repeat
Acc: digital bursted, reaction time, control, more decimal places
Endpoint vs equivalence point
Endpoint (occurs after): point where indicator changes colour, equivalence point (occurs first): point where neither reactant is in excess
Aim of a titration
to determine the concentration of an unknown acid/base by reacting it with a solution of known concentration
What indicator?
Phenophthalein 8,2-10 (just after equivalence point)
Colourless -> pink (add base to acid)
Why swirl?
- avoid concentration of titrant in one spot/ swirl to endure entire solution has reached endpoint
Data table
columns have units and headings, table doesn’t have a heading
Order doesn’t matter
range
max-min
What do you need to determine accuracy?
an actual real value
Diagram
Labelled
Method
3rd, past tense
Numbered
More than 1 trial
Safety precautions
Fair test (controlled var)
Control
Values
Conclusion
aim/ in agreement with…
What was measured
Possible human error
Both var
Aim
To find the value Of unknown by measuring the …
