Stoichiometry Theory Flashcards
Define the molecular formula of a compound.
The Molecular Formula of a compound is the number and type of different atoms in one molecule.
Define the Empirical Formula fof a compound.
The Empirical Formula of a compound is the simplest whole number ratio of the different atoms or ions in a compound.
Ionic Compound formulas are always empirical.
A magnesium ion is Mg2-and a nitrogen ion is N3-.
From this, deduce their formula.
The formula of Mg²⁻ and N³⁻ is Mg₃N₂.
This is the Ionic Compound, Magnesium Nitride.
What is the method for deducing the formula of an ionic compound like Al2O3 (Aluminium Oxide)?
The method for deducing the molecular formula of simple compounds like the ionic compound Al₂O₃ is by swapping the valencies or charges.
In this case, the valency of Aluminium is 3, and for Oxygen 2. Swapping these gives us Al₂O₃.
Try out some practice questions on this.
O2+ and Al3-
A molecule contains Carbon, Hydrogen and Oxygen. For every carbon atom there are twice as many hydrogen atoms but the same number of oxygen atoms.
What is the formula of the molecule?
This is a covalently bonded molecule.
The formula of this is CH₂O.
This is a simple compound.
Give the formula for the compound ion, Hydroxide.
The formula for the compound ion, Hydroxide is:
OH⁻
SINCE THERE IS ONLY ONE ION PRESENT, THE BRACKETS ARE NOT NEEDED.
THE CHARGE ON COMPOUND IONS COVERS THE WHOLE ION.
What is the formula for Carbonate, a compound ion?
The formula for Carbonate is CO₃²⁻.
SINCE THERE IS ONLY ONE ION PRESENT, THE BRACKETS ARE NOT NEEDED.
THE CHARGE ON COMPOUND IONS COVERS THE WHOLE ION.
What is the formula for Nitrate?
Nitrate is a compound ion.
The formula for the Nitrate compound ion is:
NO₃⁻
SINCE THERE IS ONLY ONE ION PRESENT, THE BRACKETS ARE NOT NEEDED.
THE CHARGE ON COMPOUND IONS COVERS THE WHOLE ION.
Give the formula for the compound ion Phosphate.
The formula for the compound ion Phosphate is PO₄³⁻
SINCE THERE IS ONLY ONE ION PRESENT, THE BRACKETS ARE NOT NEEDED.
THE CHARGE ON COMPOUND IONS COVERS THE WHOLE ION.
Give the formula of the compound ion, Sulfate.
SO₄²⁻
is the ionic compound of Sulfate.
SINCE THERE IS ONLY ONE ION PRESENT, THE BRACKETS ARE NOT NEEDED.
THE CHARGE ON COMPOUND IONS COVERS THE WHOLE ION.
State the formula of the compound ion Hydrogencarbonate.
The formula of Hydrogencarbonate is
HCO₂⁻
SINCE THERE IS ONLY ONE ION PRESENT, THE BRACKETS ARE NOT NEEDED.
THE CHARGE ON COMPOUND IONS COVERS THE WHOLE ION.
State the formula for the compound ion Ammonia.
The formula for Ammonia is NH₄⁺
SINCE THERE IS ONLY ONE ION PRESENT, THE BRACKETS ARE NOT NEEDED.
THE CHARGE ON COMPOUND IONS COVERS THE WHOLE ION.
What is the formula for the ion Mg2+ and the compound ion, {NO3}- ?
The formula for Mg²⁺ and NO₃⁻ is
Mg[NO3]2
IF THERE IS ONLY ONE ION PRESENT, THE BRACKETS ARE NOT NEEDED.
How would one calculate the empirical formula from the molecular formula of a compound?
Example: C6H18O3
To derive the empirical formula from the molecular formula, the subscripts of the molecular formula would be divided by their lowest common factor.
In this case, this is 3. The Molecular formula of C₆H₁₈O₃ is thus:
C₂H₆O
Ionic Compound formulas are always empirical.
Write the symbol equation, with state symbols, for the reaction of, aqueous Sodium hydroxide with, aqueous Hydrochloric acid [HCl] to form, aqueous Sodium chloride and liquid water.
The symbol equation:
is
NaOH {aq} + HCl {aq} –» NaCl {aq} + H₂O {l}
Use practice questions for effective practice of this topic.
