Chemistry

Semester 1 C4E Exam

Shapes of molecules

Tetrahedral, linear, bent/v-shape, trigonal pyramidal, trigonal planar

VSEPR Theory

Valance Shell Electron Pair Repulsion Theory; the theory that valence electron pairs repel against each other and arrange themselves as fair a part as possible.

Three Covalent Network Lattices

Graphite, Diamond and Silicon dioxide

Intramolecular bonding types (PRIMARY BONDING)

Covalent (non-metal/non-metal), Metallic (metal/metal), Ionic (non-metal/metal)

Intermolecular bonding types (SECONDARY BONDING)

Dispersion forces, dipole-dipole forces, hydrogen bonding and ion-dipole interactions

What is one example of an acid rain equation?

SO₂(g) + H₂O(l) —> H₂SO₃(aq)

Conjugate Acid

When a base accepts a proton, what forms is its conjugate acid

Conjugate Base

When an acid donates a proton, what remains is its conjugate base

Which Acid equation is known as a ‘neutralisation reaction’

Reaction #2: Acid + Base —> Salt + Water (H₂O)

What causes a positive pop test?

A positive pop test occurs when hydrogen gas (H₂) is present and is ignited.

What causes a ‘mass loss’

A ‘mass loss’ occurs when a gas is formed, and escapes. In Acid/Base Chemistry, Reaction #1 results in H₂(g), and Reaction #4 and #5 result in CO₂(g). This results in a mass loss for these reaction equations.

Bronsted-Lowry Theory

Acids donate proton (H⁺), and bases accept proton (H⁺)

Effects of Acid Rain

When acid rain falls, it gets absorbed into soil, and then enters the ocean through run-off. Ocean water then acidifies. Shellfish rely on calcium carbonate for their structure, and acidified water can dissolve their structures. This impacts coastal communities who rely on fishing for economic income.

(ACID/BASE CHEMISTRY) Reaction #1

Acid(aq) + Metal(s) —> Salt(aq) + Hydrogen gas(g) (H₂)

(ACID/BASE CHEMISTRY) Reaction #2

Acid(aq) + Base(aq) —> Salt(aq) + Water(l) (H₂O)

(ACID/BASE CHEMISTRY) Reaction #3

Acid(aq) + Metal Oxide(s) —> Salt(aq) + Water(l) (H₂O)

(ACID/BASE CHEMISTRY) Reaction #4 & Reaction #5

Acid(aq) + Metal Carbonate(s)/Metal Hydrogen Carbonate(s) —> Salt(aq) + Water(l) (H₂O) + Carbon Dioxide(g) (CO₂)

Strength vs. Concentration

Strength: Level of ionisation of H⁺ (qualitative). Concentration: Amount of acid/base present in solution (quantitative).

Strong Acid

All particles ionised. Readily donates H⁺ ions

Strong Base

All particles ionised. Readily accepts H⁺ ions

Weak Acid

Not many particles ionised. Does NOT readily donate H⁺ ions

Weak Base

Not many particles ionised. Does NOT readily accept H⁺ ions

Define an amphiprotic substance

Amphiprotic Substances can act as both an acid and a base. They can both donate, or accept a proton (H⁺), depending on what they are reacting with.

Examples of an amphiprotic substance

H₂O, HCO₃^-, H₂PO₄^-, HPO₄^-, HSO₄^-