Acids and bases Flashcards
What is the definition of a strong acid?
Acid that fully dissociates
What is the definition of a weak acid?
Acid that partially dissociates use reversable sign in equations
Write the equation for calculating Ph using acid concentration.
Ph= -Log(H+)
How do you work out acid concertation when a molecule has the OH- ion?
Use the Kw formula where Kw is a constant. Kw/(OH-)
What is the definition of a conjugate base?
Two species differing by a H+ ion
What does Ka stand for?
Weak acid dissociation constant
Ka equation.
Ka=(H+)(product 1)/ (Reactants)
If Ka is less than 1 acid is ? likewise if it is bigger than 1?
weak, it is strong.
For weak acids what is the equation at equilibrium?
(H+)=(A-)
What is a monobasic acid?
Only donates one mole of protons per mole of acid
What is a buffer?
A system that minimises change in the Ph when small amounts of acid or alkali are added.
What is different between the 2 methods to calculate buffer solution?
-method one is acid + substance
-method two is acid + base i.e __ hydroxide, carbonates, ammonia
Explain how to do method 2.
-Calculate mols of both acid and base.
-Calculate the mols in excess, subtracting. Excess mols are known as [A-]
-Calculate conc of [HA] by doing excess mols/total volume
-Calculate conc of [A-] by doing [A-] mols/ total volume
-Replace in H+ equation and calculate Ph
When is pKA used?
-When Ka value is very large for weak acids, the values themselves are smaller numbers.
Define Equivalence point
-Centre point of the vertical section of the titration.
