Topic 1: Stoichiometric Relationships
1.1 States of Matter
The three states of matter ​​
Change of State
Types of Matter
Types of reactions
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Combination or synthesis (Example)
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Decomposition​​ (Example)
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Simple replacement (Example)​
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Double replacement​ (Example)
Utilization
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Atom Economy
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Definition: "Measure that accounts for the efficiency of chemical reactions by comparing the amount of reactants with the amount of products."
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Formula:
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Freeze-drying of foods:​ Low temperature and low pressure to sublime water, in order to maintain taste.
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Refrigeration: Energy changes during the evaporation and condensation of a volatile fluid under changing pressure.
1.2 Amount of Substance
Relative atomic mass (Ar)
Definition: The weighted average of the atomic masses of its isotopes and their relative abundance, compared to 1/12th of a carbon-12 atom. Unit:
Same concept is applied for Relative Molecular mass
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Molecular formula
Definition: "The actual number of of atoms of each element in one compound." (Bylikin, 2014)
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Example: Ethane:
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Relative amount of substance​
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Formula:
Mole (n)
Definition: an SI unit defined as a fixed amount of substance. For instance, a dozen is 12 units of something, the same way a mole is units of something.
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Empirical formula
Definition: "the simplest whole number ratio of atoms of each element in one compound." (Bylikin, 2014)
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Example: Ethane:
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1.3 Stoichiometry
Definitions
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Stoichiometry: the quantitative method of examining the relative amounts of reactant and products.
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Limiting agent: the reactant that will be completely consumed during the reaction.
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Yields
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Theoretical yield: the yield that is calculated.
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Experimental yield: the yield that is obtained.
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Difference between yields due to:
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impurities
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change in the conditions of a reaction
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reverse reactions
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side reactions
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loss of product
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Percentage yield:​
​Note: The concepts of yields are very important for industries. One important example is the Haber-Bosch process (production of ammonia).
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Gases
STP (Standard temperature and pressure): 273 K and 100kPa
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Molar volume of a gas
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Definition: "the volume of 1 mole of a gas a constant at a given temperature and pressure."
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Assumptions:
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Gases are made from small particles
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Particles move in straight lines and in different directions
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There is no kinetic energy loss
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There is no force of attraction between molecules
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Molar volume of a gas at STP​:​
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- ​Gas Laws:
- Formula​​:
- ​Tip: this formula involves the change in temperature, pressure or volume.
Note: Temperature is always in K
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- Ideal Gas Equation:
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Formula:
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​Titration:
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A quantitative and volumetric analysis
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Generally uses indicators
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Example: Acid-Base titrations or potentiometric titrations (not in the core syllabus)
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Utilization
Air bags: the use of gas laws to "play"the correlation between pressure, temperature and volume in order to quickly expand the total volume of the air bag in case of an accident.
​​Tip: this formula does not involve the change in temperature, pressure or volume.
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Solutions
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Concentration:
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Formula:
