PHAR1101 Lecture Notes - Lecture 3: Ionic Compound, Solubility, Atomic Number
Pre lecture 3
Diatomic elements:
•do not occur naturally as single elements
•exists as diatomic elements - two atoms combine to form a molecule
•Have No Fear Of Ice Cold Beer
Pre-lab
Solubility rules:
•all salts containing nitrates are soluble
•all salts containing sodium cations are soluble
No observable change to the form of the chemicals on the reaction side compared to product
side = no reaction took place
Four driving forces - favour chemical change
1. Formation of solid
2. formation of water
3. transfer of electrons
4. Formation of gas
Dissolution (ionic compound dissolves)
•ions separate and move around independently
•strong electrolyte- each units that dissolves with water produces separated ions
Solid reactions
•Precipitation reaction
Predicting precipitates
1. Write the reactants as they actually exist before any reaction occurs. When a salt dissolves, its
ions seperate
2. consider the various solids that could form, simple exchange the anions of the added salts
3. use solubility rules to decide whether a solid form and if so, to predict the identity of the
solids
Lecture 3
Daltons theory:
•most natural material were mixtures of pure substances
•pure substances are made up of elements/compounds
•a given compound always contains the same proportion (by mass) of the elements
Law of constant composition
•a given compound always has the same composition, regardless of where it comes from.
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Document Summary
Diatomic elements: do not occur naturally as single elements, exists as diatomic elements - two atoms combine to form a molecule, have no fear of ice cold beer. Solubility rules: all salts containing nitrates are soluble, all salts containing sodium cations are soluble. No observable change to the form of the chemicals on the reaction side compared to product side = no reaction took place. Four driving forces - favour chemical change: formation of solid. 3. transfer of electrons: formation of gas. Dissolution (ionic compound dissolves: ions separate and move around independently, strong electrolyte- each units that dissolves with water produces separated ions. Predicting precipitates: write the reactants as they actually exist before any reaction occurs. Daltons theory: most natural material were mixtures of pure substances, pure substances are made up of elements/compounds, a given compound always contains the same proportion (by mass) of the elements.
