Acids and bases

What is a Bronsted-Lowry acid?

proton donor

What is a Bronsted-Lowry base?

proton acceptor

What is the formula for calculating pH?

pH = - log [H+]

What happens to strong acids in solution?

They completely dissociate.

How is the pH of a strong acid related to its concentration?

The concentration of hydrogen ions is the same as the concentration of the acid.

What is the pH of a 0.1 mol dm-3 HCl solution?

pH = 1.00.

How do you find [H+] from pH?

[H+] = 1 x 10^-pH.

What is the ionic product for water (Kw) at 25°C?

Kw = 1 x 10^-14 mol² dm^-6.

What is the relationship between [H+] and [OH-] in pure water?

[H+] = [OH-].

What is the pH of pure water at 25°C?

pH = 7.

How does temperature affect the pH of pure water?

Increasing temperature increases [H+], thus lowering pH.

What is the dissociation equation for water?

H2O (l) ⇌ H+ (aq) + OH- (aq).

What is the dissociation expression for weak acids?

HA ⇌ H+ (aq) + A- (aq).

What is Ka?

The acid dissociation constant, representing the strength of an acid.

What is the relationship between Ka and pKa?

pKa = -log(Ka).

How do you calculate the pH of a weak acid?

Use the Ka expression and assume [H+]eqm = [A-]eqm.

How do you calculate the concentration of an acid from its pH?

[H+] = 1 x 10^-pH.

What is the method for calculating pH in neutralization reactions?

Determine excess H+ or OH- ions and calculate pH accordingly.

What is the pH of a solution with excess H+ ions?

pH = -log[H+].

How do you find the new concentration of excess OH- ions after neutralization?

[OH-] = moles excess OH- / total volume (dm3).

What is the dissociation equation for NaOH in water?

NaOH → Na+ + OH-.

How do you calculate the pH of a partially neutralized acid?

Calculate moles of acid and base, then find excess ions.

What is the reaction between H+ and OH-?

H+ + OH- → H2O

How do you find moles of OH- in excess?

Moles of OH- in excess = moles NaOH - moles HCl

What is the formula for calculating [H+] in a solution?

[H+] = moles excess H+ / total volume (dm3)

What is the pH formula in relation to [H+]?

pH = -log[H+]

How do you calculate the pH of a strong diprotic acid like H2SO4?

Moles H+ = 2 x moles H2SO4

What is the formula for calculating the concentration of a weak acid after neutralization?

[HA] = (initial moles HA - moles OH-) / total volume (dm3)

What is the equilibrium expression for weak acid dissociation?

Ka = [H+][A-] / [HA]

What happens at half equivalence point in a weak acid-strong base reaction?

At half neutralization, [HA] = [A-] and pH = pKa

How do you calculate the new concentration of [H+] after dilution?

[H+] = [H+]old x old volume / new volume

What is a buffer solution?

A solution that resists changes in pH when small amounts of acid or base are added.

What components make up an acidic buffer solution?

A weak acid and a salt of that weak acid.

What is the role of the salt in a buffer solution?

It provides a reservoir of conjugate base to maintain pH.

What happens when acid is added to a buffer solution?

The equilibrium shifts to the left, removing H+ ions.

What happens when alkali is added to a buffer solution?

The OH- ions react with H+ to form water, shifting equilibrium to the right.

How do you calculate the pH of a buffer solution?

Use the equation: pH = pKa + log([A-]/[HA])

What is the dissociation constant (Ka) for acetic acid?

Ka = 1.7 x 10^-5 mol dm^-3

What is the effect of dilution on the pH of a strong acid?

Dilution decreases [H+] and increases pH.

How do you calculate the pH of a solution with excess H+?

Use the formula pH = -log[H+].

What is the concentration of OH- in a solution with excess OH-?

[OH-] = moles excess OH- / total volume (dm3)

How do you find the moles of a weak acid after reacting with a strong base?

Calculate moles of weak acid and subtract moles of strong base.

What is the effect of adding a strong base to a weak acid?

It neutralizes the weak acid, producing salt and water.

How is the pH of a buffer calculated when made from ethanoic acid and sodium ethanoate?

Use the equation: pH = pKa + log([A-]/[HA]).

What is the formula to calculate moles of a solution?

Moles = concentration (mol/dm³) x volume (dm³).

What happens to the pH of a buffer when a small amount of acid is added?

The moles of buffer salt decrease and moles of buffer acid increase, requiring a new pH calculation.

What is the effect of diluting a buffer solution on its pH?

Diluting a buffer solution with water does not change its pH.

What is the pH at the equivalence point of a strong acid-strong base titration?

The pH at the equivalence point is typically 7.

What is the significance of the half-neutralization volume in titrations?

At half-neutralization, [HA] = [A-], and pH = pKa.

How do you determine the pH of a buffer after adding NaOH?

Calculate the new moles of acid and salt, then use the buffer equation.

What is the role of indicators in titrations?

Indicators change color at a specific pH range, signaling the endpoint of the titration.

What is the color change of phenolphthalein in a titration?

Phenolphthalein changes from colorless in acid to pink in alkali.

What is the color change of methyl orange during a titration?

Methyl orange changes from red in acid to yellow in alkali.

What is the formula for calculating the pH of a buffer solution made from a weak acid and its salt?

pH = pKa + log([salt]/[acid]).

What happens to the pH of a buffer when a small amount of alkali is added?

The moles of buffer acid decrease and moles of buffer salt increase, requiring a new pH calculation.

What is the general shape of a titration curve for a weak acid and strong base?

The curve rises quickly and levels off, with a buffer region formed.

What is the pH at the equivalence point for a weak acid-strong base titration?

The pH is greater than 7.

What is the significance of calibrating a pH meter?

Calibration ensures accurate pH measurements, often using standard buffer solutions.

What is the effect of temperature on pH measurements?

Maintaining a constant temperature improves the accuracy of pH measurements.

What is the relationship between pKa and pH at half-neutralization?

At half-neutralization, pH = pKa.

What is the effect of adding a solid salt to a buffer solution?

Adding a solid salt increases the concentration of the conjugate base, affecting the pH.

What is the purpose of using a pH curve in titrations?

The pH curve helps visualize the changes in pH during the titration process.

What is the formula for calculating the concentration of H+ ions in a buffer solution?

[H+] = Ka x [HA]/[A-].

What is the impact of adding a strong acid to a buffer solution?

The buffer acid increases while the buffer salt decreases, requiring a new pH calculation.