Stoichiometry Quiz

Study Notes

Study of the quantitative relationships between reactants and products in a chemical reaction
Deals with the calculation of the amount of reactants required or products formed in a reaction
Stoichiometric coefficients:
- Whole numbers that represent the ratio of molecules of reactants to products
- Used to balance chemical equations
Moles:
- A unit of measurement for the amount of a substance
- 1 mole = 6.022 x 10^23 particles (atoms, molecules, ions)
Molar ratios:
- Used to relate the amount of one substance to another in a reaction
- Calculated using stoichiometric coefficients and molecular weights

Process of adjusting the coefficients of reactants and products to satisfy the law of conservation of mass
Steps to balance an equation:
1. Write the unbalanced equation
2. Count the atoms of each element on both sides of the equation
3. Add coefficients in front of formulas to balance the equation
4. Check that the equation is balanced by counting atoms again
Tips for balancing equations:
- Start with elements that appear in the greatest number of formulas
- Balance elements that are combined in a single formula last
- Use fractional coefficients as a last resort

Neutralization reactions between acids and bases
Acid:
- A species that donates a proton (H+)
- Examples: HCl, H2SO4, CH3COOH
Base:
- A species that accepts a proton (H+)
- Examples: NaOH, Ca(OH)2, NH3
Acid-base reactions:
- Acid + Base → Salt + Water
- Example: HCl + NaOH → NaCl + H2O
pH:
- A measure of the concentration of H+ ions in a solution
- pH = -log[H+]

Reactions that involve the transfer of electrons
Oxidation:
- Loss of one or more electrons
- Increase in oxidation number
Reduction:
- Gain of one or more electrons
- Decrease in oxidation number
Oxidizing agent:
- A species that causes oxidation to occur
- Also known as an electron acceptor
Reducing agent:
- A species that causes reduction to occur
- Also known as an electron donor
Example of an oxidation-reduction reaction:
- 2Cu + O2 → 2CuO (copper is oxidized, oxygen is reduced)

The process of increasing the rate of a chemical reaction using a catalyst
Catalyst:
- A species that speeds up a reaction without being consumed or altered
- Examples: enzymes, metals, metal oxides
How catalysts work:
- Lower the activation energy required for a reaction to occur
- Provide an alternative reaction pathway with lower energy requirements
Types of catalysis:
- Homogeneous catalysis: catalyst is in the same phase as the reactants
- Heterogeneous catalysis: catalyst is in a different phase from the reactants

Quantitative relationships between reactants and products in a chemical reaction involve calculating the amount of reactants required or products formed
Stoichiometric coefficients represent the ratio of molecules of reactants to products and are used to balance chemical equations
Moles are a unit of measurement for the amount of a substance, with 1 mole equal to 6.022 x 10^23 particles
Molar ratios relate the amount of one substance to another in a reaction and are calculated using stoichiometric coefficients and molecular weights

The process of balancing equations involves adjusting coefficients of reactants and products to satisfy the law of conservation of mass
To balance an equation, count the atoms of each element on both sides, add coefficients to balance, and check the equation again
Tips for balancing equations include starting with elements that appear in the greatest number of formulas and balancing elements combined in a single formula last

Acid-base reactions involve neutralization between acids and bases, with acids donating protons (H+) and bases accepting them
Examples of acids include HCl, H2SO4, and CH3COOH, while examples of bases include NaOH, Ca(OH)2, and NH3
Acid-base reactions produce salt and water, with pH measuring the concentration of H+ ions in a solution (pH = -log[H+])

Oxidation-reduction reactions involve the transfer of electrons, with oxidation being the loss of one or more electrons and reduction being the gain
Oxidizing agents cause oxidation, while reducing agents cause reduction, with examples including the reaction between copper and oxygen (2Cu + O2 → 2CuO)
In this reaction, copper is oxidized and oxygen is reduced

Catalysis involves increasing the rate of a chemical reaction using a catalyst, which speeds up the reaction without being consumed or altered
Catalysts lower the activation energy required for a reaction to occur and provide an alternative reaction pathway with lower energy requirements
Examples of catalysts include enzymes, metals, and metal oxides, with types of catalysis including homogeneous and heterogeneous catalysis