SACE Stage 1 Chemistry Unit 5 Test- Acids and Bases

What is an Acid?

A substance that donates protons, and creates H₃O

What is a Base?

A substance that accepts protons, and creates OH

What are strong acids?

Acids that fully ionise in water (1 moll of acid → one mol of H₃O

What are Weak acids?

Acids that partially ionise in water, creating less than one mole of hydronium

What is a conjugate acid?

A conjugate Acid is when an base has accepted the proton, and can only accept one, so if the reaction is reversed, it would give this proton it has accepted

What is a conjugate base?

A conjugate base is when an acid has given its proton, and the acid can only give one, so when the reaction is reversed, it would receive the proton.

What are conjugate pairs?

An example of a conjugate pair is an acid and a conjugate base

What are non metal oxides?

Acidic

What is another name for non metal oxides

acidic oxides

When Non metal oxides react with water what do they make?

Acids

Example of a acidic oxide reacting with water to create an acid

SO₂+ H₂O→ H₂SO₃

When Acidic oxides react with a base, they form:

When metal oxides react with an acid, they form

oxyanion or cation and water ( )

metal oxides are

Commonly basic

Metal oxides react with water to form:

hydroxide ions,

Metal oxides react with water create a base, so they are called

basic oxides

When metallic( basic) oxides react with acids, they release

A cation and water.

Oxides and hydroxides of metals are

considered basic

When metallic hydroxide or oxides react with acids

They are called neutralisation reactions

Basic Oxide + acid

→ Salt +water

ionic compounds formed in acid base reactions are called

Salts

Metal carbonates when neutralised with an acid make:

Salt, water and +carbon dioxide

What is a monoprotic acid?

An acid that can only donate 1 proton

What is a diprotic acid ?

An acid that can donate 2 protons

What is a triprotic acid?

an acid that can donate 3 protons

Stochiometry Steps:

1.     Write fully balanced chemical equation

2.     Find the number of moles of known solution (n=c x v)

3.     Use mole ratio to find moles

4.     Calculate concentration (c = n/v) OR volume (v = n/c)

Pure water has ions present

due to the proton transfer between water (creating H₃O^- and OH⁺

The amount of ions in water is (K_w)

1×10^-14

in a neutral solution of pH 7

concentration of hydronium and hydroxide ions are equal

If a concentration of one ion is increased,

the other should be decreased propotionally

At 25c:

acidic if [H₃O⁺] > 10^-7 mol/L

  neutral if [H₃O⁺] = 10^-7 mol/L = [OH^-]

  basic if [OH^-] > 10^-7 mol/L

The pH scale indicates

the acidity of a solution (power of H=pH)

The acidity of a solution

is expressed as a negative logarithm of the hydrogen ion concentration in solution.

The pH of a solution decreases

as the concentration of hydrogen ions increases.

The hydronium concentration can be determined

from the pH.

The pH scale is a useful way of indicating the acidity of a solution.

Mathematically, pH is defined as:

pH = -log [H₃O⁺]

What does [ ] mean in chemistry?

concentration

[H₃O] is in

Mol/L

If the pH is known, the Hydronium concentration can be found by:

[H₃O]= 10^-pH

pH+pOH

= 1×10^-14

If the hydronium or hydroxide is known, and the other is needed to be found:

[OH]= H₃O/1×10^-14

Amphoteric oxides are classified as

metal oxides that react with both acids as well as bases to create salts and water.

Acid rain is determined by having a pH lower than

5.6

what is the formation of acid rain through Sulphur oxide.

Sulphur is a contaminant in fossil fuels. When Fossil Fuels are burnt, so is sulphur, and it becomes sulphur dioxide. Sulphur dioxide then combines with more oxygen (O₂) and becomes Sulphur Trioxide (SO₃). Sulphur trioxide then dissolves in water, which creates sulphuric acid (H₂SO₄) which is precipitated in the rain. Sulphuric Acid significantly lowers the pH, as when the Sulphuric Acid dissolves in other rain water, it forms hydronium, which lowers pH, and sulphate (SO₄)

What is the formulaic description of the formation of Suphuric acid rain

S + O₂ → SO₂

2SO₂ + O₂ →2SO₃

SO₃ +H₂O → H₂SO₄

H₂SO₄ +2H₂O → 2H₃O⁺ + SO₄^-

how is an average titre found?

Divide the total volume by the number of trials to obtain the average titre. (with auto doing the first rough titration, and all must be concord)

Weak acids are

Reversible, so use ⇌

what is concordant in triation?

In titration, concordant titres refer to results that are closely similar in value, typically within 0.1 mL of each other.

strong acid conducts better than weak acids as

there are more ions in the solution, as weak acid equations reverse back and forth.

Amphoteric

(of a compound, especially a metal oxide or hydroxide) able to react both as a base and as an acid)

Water is Amphoteric