Unit 9 Buffers, Titrations, Solubility Flashcards
what is the common ion effect?
decrease in solubility of an ionic precipitate upon the addition of a substance involved in that equilibrium
what does the addition of acetic acid to a solution of acetic acid do to the dissociation of the acid
suppresses the dissociation of the acid
What is a buffer solution?
A solution that can resist pH change after the addition of a weak acid or base
Can you make a buffer with a strong acid or base?
no
What is the amount of acids and bases in a good buffer?
they are around the same amout
What is the formula for the Henderson hassle bach equation?
pH=pka+log[A-]/[HA]
what is the Henderson hassle bach formula used for?
Used for calculating the pH of buffers with known concentrations or determining how to make a buffer at a desired pH
how do you make a buffer solution?
- Select an acid with pka close to the desired pH
- Mixed equal amounts of acids with its conjugate base
- Adjust to desired pH by adding small amounts of strong acid or b
Can buffers tolerate infinite amounts of strong acids and bases?
no
what happens to the buffer if more acid or base is added than the buffer can handle?
the buffer is destroyed
What is buffer capacity?
the amount in mols of acid or base a buffer can handle without significant changes in pH
What do small shifts in pH result from?
large shifts in acids and bases
What is titration?
a process for determining the concentration of a solution by
carefully adding the addition of the volume of the other element whose concentration is known
What is Titration involving only strong acids and bases like?
straightforward
What are Titrations involving weak acids and bases like and why?
complicated by hydrolysis of salts
When does an indicator change colour? What colour does it change to?
when the reaction is completed. Changes from colourless to pink
What is the equivalence point? what are the moles of acid and base like at this point?
point in titration reaction where the amount of titrant added was able to neutralize the solution (moles of acid are equal to mols of base)
How is the equivalence point related to the pH of salt?
equivalent point is dictated by the pH of the salt that is formed
What is the pH of weak acids?
pH if 4-6 is considered a weak acid
What is the pH of strong acids?
pH of 0-1 is considered a strong acid
What is the pH of weak bases?
pH between 7.1-10
What is the pH of strong bases?
pH between 10-14 is considered a strong base
In a Strong base strong acid titration, what is the concentration of OH- like before equilibrium?
in excess
What is solubility?
the ability of a solute to dissolve in another substance (solvent)
What does it mean when two substances dissolve at a constant rate?
then the two substances are at equilibrium
When does a solution stop being unsaturated?
until it reaches the maximum amount of solute it can dissolve
What are the factors that affect solubility?
Temperature, pressure, molarity, and molecular size
how do find the volume given two concentrations and a volume?
- make an equation
- find the mols of the known
- use molar ratio to find the mols of the unknown
- solve for the unknown volume L=mol/M
remember to change to volume to litres
how to do find the concentration given the volume of the unknown and the mols and volume of the known concentration
- make an equation
- find the moles of the known
- use the molar ratio to find the mols of the unknown
- solve for unknown concentration M=mol/L
