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AH Chemistry 🧪 > Equilibrium > Flashcards

Equilibrium Flashcards

1
Q

What two things make dynamic equilibrium?

A

Rate of reaction is equal

Concentration is constant

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2
Q

What value is given to the equilibrium constant?

A

K

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3
Q

What equation is used for equilibrium constant?

A

K = [product] / [reactants]

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4
Q

What do you ignore when working out equilibrium constants?

A
  1. Water unless in same state as everything else
  2. Pure solids
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5
Q

How does changing concentration move equilibrium?

A

Adding reactants = more products

Adding Products = more reactants

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6
Q

How does changing pressure move equilibrium?

A

Increasing pressure causes equilibrium to shift to the side with fewer moles of gas

Decreasing pressure causes equilibrium to shift to the side with greater moles of gas’

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7
Q

How does changing temperature move equilibrium?

A

Exothermic = decrease favours exothermic

Endothermic = increase favours endothermic

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8
Q

What is the main sign for identifying a weak or strong base/acid in a solution?

A

Strong - 1 headed arrow

Weal - Double headed arrow (like in equilibrium)

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9
Q

What are strong and weak acids?

A

Strong acid - all molecules dissociate (ionise) in water

Weak acid - only some molecules dissociate when dissolved in water

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10
Q

What are strong and weak bases?

A

Strong base - all molecules dissociate when dissolved in water

Weak base - only some molecules dissociate when dissolved in water

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11
Q

3 strong acid examples:
4 weak acid examples:

A

Strong
- hydrochloride acid
- nitric acids
- sulfuric acid

Weak
- ethanoic acid
- carboxylic acids
- carbonic acid
- sulphurous acid

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12
Q

1 strong base examples:
1 weak base examples:

A

Strong
- sodium hydroxide

Weak
- ammonia

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13
Q

Strong acid + strong base =

A

Neutral solution

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14
Q

Strong acid + weak base =

A

Acidic solution

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15
Q

Weak acid + strong base =

A

Alkaline solution

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16
Q

Why do some salts produce acidic solutions?

A

The ions from the weak base and the water combine. This leaves an excess of H+ ions in the solution (acid doesn’t reform as it dissociates completely)

17
Q

Why do some salts produce alkaline solutions?

A

The ions from the weak acid and water combine to form a weak acid leaving an excess of OH- ions in the solution (alkali doesn’t reform as it just dissociates again)

18
Q

What is the ionic product of water at 25°C?

What is the equilibrium constant for water dissociation that proves this?

A

x10-14

K = [H3O+][OH-]

19
Q

Do H+ ions or OH- ions indicate the pH?

A

H+ ions

20
Q

Why do ionic products of water increase with temperature changing the pH?

A

Water dissociation is a equilibrium

Forward reaction = endothermic

Reverse reaction = exothermic

21
Q

What does the water dissociation equilibrium equation look like?

A

H2O + H2O

H3O+ + OH-

22
Q

What is the pH scale directly related to?

A

Concentration of H3O+ ions in a solution

23
Q

What equation is used for the pH of strong acids and bases?

A

pH = -log[H+]

24
Q

Does concentration = pH in strong or weak acids?

A

Strong as acid completely dissociates
H+ concentration = pH

25
Q

What are the two equations used for finding the pH of weak acids and bases?

A

Ka= products/reactants

pH= 1/2pKa - 1/2logC

pKa = -log(Ka)

26
Q

What does a large Ka value and small pKa value indicate?

A

A strong weak acid

27
Q

What does a small Ka value and large pKa value indicate?

A

A strong weak base

28
Q

When does colour change occur in an indicator?
What equation can work it out?

A

When pH = pKin +/- 1

pKin = -log[Kin]

29
Q

When are weak acid and weak base react can an indicator be used?

A

No

30
Q

What makes an acidic buffer?

What makes a basic buffer?

A

A weak acid and one of its salts

A weak base and one of its salts

31
Q

What happens when H3O+ ions are removed from an acidic buffer?

What happens when H3O+ ions are added from an acidic buffer?

A

The weak acid provides more H3O+ ions

The conjugate acid from the salt reacts with them to form the weak acid and because is completely dissociates it has lots of ions to do so.

32
Q

What happens when OH- ions are removed from an basic buffer?

What happens when OH- ions are added from an basic buffer?

A

The weak base will provide more OH- ions

The conjugate acid provided by the salt removes them by forming the weak base

33
Q

What equation calculates a buffer solutions pH?

A

pH = pKa - log ([acid]/[base])

AH Chemistry 🧪 (5 decks)

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