Concepts of Acids and Bases

What is an acid? What does it Produce (in what liquid)?

A substance with a pH less than 7; produces H+ ions in water (a proton/H+ donor)

What is a base? What does it produce?

A substance with a pH greater than 7; produces OH- ions in water (a proton acceptor)

What is pH? What is it used to express (2)?

A logarithmic scale of H+ concentration in a solution; used to express acidity or basicity

pH = what ? (calculation)

-log[H+]

What is the range of the pH scale?

0 to 14

What is a neutral pH? Define the H+ and OH- ratio

pH 7, where H+ and OH- concentrations are equal

What is the pH of an acidic solution? Define the H+ and OH- concentration ratio

Less than 7; more H+ than OH-

What is the pH of a basic solution? Define the H+ and OH- ratios

Greater than 7; more OH- than H+

What is the pH of human blood?

~7.4 (close to neutral)

What happens to pH when a base is added to a solution?

pH rises

What happens to pH when an acid is added to a solution?

pH falls

What is the hydronium ion? How is it formed?

H3O+, formed when an H+ ion bonds to a H2O molecule

Define the term → disassociates

When a compound breaks apart into ions or molecules in a solution

Define a strong acid?

An acid that completely dissociates in water (e.g., HCl)

Define a weak acid?

An acid that does not fully dissociate in water (e.g., acetic acid)

Define a strong base?

A base that completely dissociates in water (e.g., NaOH)

Define a weak base?

A base where not every molecule accepts protons, so the reaction is reversible (e.g., NH3)

Who is the proton donor?

an acid

Who is a proton acceptor?

A base

What are examples of strong acids? (3)

HCL, HBr, HNO3

What are examples of strong bases? (3)

NaOH, LiOH, Ca(OH)₂

What are the physical properties of bases? (2)

Bitter taste and slippery feel (they react with skin oils to form a soap-like compound)

Define what a buffer is?

A solution of a weak acid and its conjugate base (or a weak base and its conjugate acid) that resists changes in pH

What is the role of buffers in the body?

Absorb excess H+ or OH

What is the main buffer system in blood? (2)

The carbonic acid (H₂CO₃) and bicarbonate (HCO3-) system

What is the source of carbonic acid in the body?

CO2 from cellular metabolism reacts with H2O (CO2 + H2O ⇌ H2CO3)

What is the role of carbonic acid in the blood buffer?

weak acid; it donates H+ when a base is added

What is the role of bicarbonate in the blood buffer?

The conjugate base; it accepts H+ to neutralize added acid

What is the carbonic acid dissociation reaction?

H₂CO₃ ⇌ H+ + HCO₃

What is a neutralization reaction? What does it form?

A reaction in which mixing an acid with a base causes the H+ to combine with the OH-; forms water

What are the products of an acid-base neutralization reaction? (2)

Water and a salt (an ionic compound)

What is the neutralization reaction of HCl and NaOH?

HCl + NaOH → H2O + NaCl

What is the pH when equal moles of acid and base are mixed?

7 (neutral)

What is the overall reaction of HCl in water?

HCl + H2O → H3O+ + Cl-