Acid-base Equilibrium Flashcards by Caolan Cunningham

What is the equivalence point

When the acid and alkali are equal

How well did you know this?

Not at all

Perfectly

What is the colour change and range for methyl orange

Red to yellow

3.1 - 4.4

How well did you know this?

Not at all

Perfectly

Phenolphthalein range and colour change

8.3 - 10.0

Colourless to pink

How well did you know this?

Not at all

Perfectly

Indicator for a strong acid and strong alkali

All 3

How well did you know this?

Not at all

Perfectly

Indicator for strong alkali and weak acid

Phenolphthalein

How well did you know this?

Not at all

Perfectly

Indicator for weak alkali and strong acid

Methyl orange

How well did you know this?

Not at all

Perfectly

Indicator for weak acid and weak alkali

Can’t use indicator

How well did you know this?

Not at all

Perfectly

Kw equation and value

(H+)(OH-)

10^-14 mol^2dm^-6
At 25 degrees
Constant for pure water and dilute acid

How well did you know this?

Not at all

Perfectly

pKw equation

-logKw

How well did you know this?

Not at all

Perfectly

pH equation

-log(H+)

How well did you know this?

Not at all

Perfectly

What is a Bronsted acid

A proton donor

How well did you know this?

Not at all

Perfectly

What is a bronsted base

Proton acceptor

How well did you know this?

Not at all

Perfectly

What effect does temperature have on Kw

⬆️ temperature = ⬆️ Kw

How well did you know this?

Not at all

Perfectly

What does Kw equal in terms of water

Kw = (H+) squared

How well did you know this?

Not at all

Perfectly

What does % ionisation refer to

The concentration of H+

How well did you know this?

Not at all

Perfectly

What is the Acidity constant (Ka) equation

See notes

What is the equation for pKa

-logKa

What does an increase in dissociation mean in terms of Ka and pKa

⬆️ dissociation = ⬆️ Ka = ⬇️ pKa = stronger acid

Strong acid fully dissociates ➡️ high conc of H+ in (aq) solution ➡️ higher Ka

What is the basicity of an acid

No. Of H+ one molecule of an acid can produce in solution on complete ionisation.
Eg monobasic, dibasic, tribasic

What is the effect upon the dissociation constant on ionisation of polyprotic acids

K1 > k2 > k3
Dissociation constant changes each time
Easier to remove H+ from neutral atom rather than negatively charged atom due to force of attraction

What is the definition of a buffer solution

Resists changes in pH on addition of small amounts of acid or alkali

What is and acid buffer solution made of

Weak acid + salt with a strong base

What is the Henderson - Hasselbalch equation

pH = pKa + log (salt)/(acid) 
() = conc.

pKa = -logKa

What is the general equation for a buffer

HA 🔁 H+ + A-

HA = undissocated acid
A- = anion
H+ = hydrogen ions

What happens when acid is added to a buffer

1. Extra H+ ions added 2. Anion of buffer reacts with H+ (A- + H+ ➡️ HA) 3. Extra H+ removed 4. Maintains H+ conc and pH

What happens when alkali is added to a buffer

1. Extra OH- added 2. These react with undissociated acid in buffer (HA + OH- ➡️ A- +H2O) (they take a H off the acid) 3. Extra OH- removed 4. Maintains H+ conc and pH

How do you measure the rate using the volume of gas evolved

See notes

How do you measure the rate of a reaction using colorimetry

See notes

Describe how you would measure the rate of a reaction by change in mass

See notes

Describe how you would measure the rate of reaction by pH change

See notes

Describe how you would measure the rate of a reaction using a titration

See notes

Describe the transition state theory

Molecules approach Slow down due to electron could repulsion Kinetic energy converted to potential energy Insufficient kinetic energy then they’ll fly apart Sufficient kinetic energy then they overcome repulsion and electrons are rearranged and product formed

Describe the activated complex

Arranged at max PE Reactant molecules partially broken New bonds partially formed

How do you determine the shape of a titration curve

See notes

How do you make a buffer solution

See notes