CL 20- acids, bases and pH

Question 1

brønsted-lowry acid

definition

Answer 1

proton donor

Question 2

brønsted-lowry base

definition

Answer 2

proton acceptor

Question 3

conjugate base of ethanoic acid

Answer 3

CH₃COO⁻

Question 4

dibasic acids

[HA] related to [H⁺]

Answer 4

[HA] = [H⁺] x2
so [H⁺] = [HA] / 2

Question 5

ionic equation for calcium + hydrochloric acid

Answer 5

Ca₍ₛ₎ + 2H⁺₍ₐ₎ –> Ca²⁺₍ₐ₎ + H₂₍₉₎

the g for hydrogen turned into a 9 for some reason

Question 6

ionic equation for calcium carbonate and sulfuric acid

Answer 6

CaCO₃₍ₛ₎ + 2H⁺₍ₐ₎ –> Ca²⁺₍ₐ₎ + CO₂₍₉₎ + H₂O₍ₗ₎

Question 7

equation for the dissociation of ethanoic acid

Answer 7

CH₃COOH₍ₐ₎ –> CH₃COO⁻₍ₐ₎ + H⁺₍ₐ₎

Question 8

relationship between Ka and pKa

Answer 8

pKa = -logKa
the lower the Ka value, the higher the pKa value

Question 9

expression for the ionic product of water, Kw

Answer 9

Kw = [H⁺][OH⁻]

Question 10

why does water have a pH of 7 at 298K?

Answer 10

[H⁺]=[OH⁻]
so Kw=[H⁺]²

Question 11

what happens to the pH of water as temperature increases?

Answer 11

• pH decreases
• because water dissociates more
• [H⁺] and [OH⁻] increases
• Kw increases

Question 12

2 approximations made to Ka expression

Answer 12

[H⁺]=[OH⁻]
[HA] at equilbrium = initial [HA]

Question 13

steps for pH of mixtures question

Answer 13

• write an equation
• find moles of acid and base
• find which is in excess
• find the moles remaining of the excess reactant
• find conc of remaining moles
• calculate pH