UNIT 8 Flashcards
What is an acid/base indicator?
Weak organic acid or base that when dissociated differes in color form its conjugate base/acid form
What are the equation for indicators?
𝐻𝐼𝑛 (𝑎𝑐𝑖𝑑𝑐𝑜𝑙𝑜𝑟) +𝐻2𝑂 ⇌ 𝐼𝑛− 𝑏𝑎𝑠𝑒𝑐𝑜𝑙𝑜𝑟 + 𝐻3𝑂+
𝐼𝑛 (𝑏𝑎𝑠𝑒𝑐𝑜𝑙𝑜𝑟) +𝐻2𝑂 ⇌ 𝐼𝑛𝐻 + (𝑎𝑐𝑖𝑑𝑐𝑜𝑙𝑜𝑟) + 𝑂𝐻−
What is the renage of color that can be detected by the observer?
10-0.1
What is the indicator range?
pka +/- 1
What are the two types of error in acid/base reactions?
Determinate
Indeterminate
Determinate error?
at the pH which the indicator changes color differs rom the pH at the equivalence point
–> pick an indicator that works
Indeterminate error?
limited ability of ht ehuman eye to distinguish reproducibly the intermediate color of the indicator
visual unicertainty is in the range of 0.5-1pH unit
What are the two sources of hydronium ions in aqueous solution?
The reaction of the acid with water
The dissociation of water itself
When can we assume that the analytical concentration of the acid is roughly equal to the concentration of hydronium ions?
When the concentration is above 1*10^-6M
How do you calculate the hypothetical titration curve? (strong acid)
pre-equivlaence
equivalence
post-equivalence
How do calculate the titration curve of weak acid/bases?
At the beginning
After various increments
At equivalence point
Beyond the equivalence point
Why are the standard reagent used in neutralization titration generally strong acids and bases rather than weak acids and bases?
Because the reactions are complete.
What indicator is used for a titration with a weak base?
indicator in the acidic range
What indicator is used for a titration with a weak acid?
Indicator in the basic range
What is the steepest point of the titraion?
End point of the titration
