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
Molecular formula
Definition: "The actual number of of atoms of each element in one compound." (Bylikin, 2014)
Example: Ethane:
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.
Empirical formula
Definition: "the simplest whole number ratio of atoms of each element in one compound." (Bylikin, 2014)
Example: Ethane:
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.
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).
Gases
STP (Standard temperature and pressure): 273 K and 100kPa
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:
- Gas Laws:
- Formula:
- Tip: this formula involves the change in temperature, pressure or volume.
Note: Temperature is always in K
- 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)
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.
Solutions
Concentration:
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Formula:
