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Questions and Answers

What role do coefficients in a balanced chemical equation play in stoichiometry?

They determine the pressure of the gases involved.

They specify the temperatures at which the reaction occurs.

They indicate the relative amounts in moles of the substances. (correct)

They describe the energy changes during a reaction.

Which statement describes a concentrated solution?

It is formed by mixing more than two substances.

It contains a small amount of solute compared to solvent.

It contains an equal amount of solute and solvent.

It has a large proportion of solute to solvent. (correct)

What is the correct stoichiometric ratio of C8H18 to CO2 from the combustion reaction?

2 mol C8H18 : 16 mol CO2 (correct)

1 mol C8H18 : 8 mol CO2

1 mol C8H18 : 18 mol CO2

25 mol C8H18 : 16 mol CO2

In a solution, what is the material present in the largest amount called?

Solvent Signup and view all the answers

How many liters of a 0.125 M NaOH solution are needed to obtain 0.255 mol NaOH?

2.04 L Signup and view all the answers

Which statement correctly describes the nature of sodium chloride when it dissolves in water?

It dissociates into ions that interact with water. Signup and view all the answers

Which of the following is true about nonelectrolytes?

They do not conduct electricity when dissolved. Signup and view all the answers

What is a characteristic of strong electrolytes?

They completely ionize when dissolved in water. Signup and view all the answers

Which of the following solutions is an example of a nonelectrolyte?

Sugar water Signup and view all the answers

What is the unit of molarity?

moles of solute per liter of solution Signup and view all the answers

What is the molarity of a solution that has 25.5 g of KBr dissolved in 1.75 L of solution, given that 1 mol of KBr has a mass of 119.00 g?

0.151 M Signup and view all the answers

How many grams of solute are present in a 2 L solution that has a molarity of 0.3 M, assuming you know the molecular weight of the solute is 58.44 g/mol?

116.88 g Signup and view all the answers

What does 'Normality' express in terms of concentration?

Moles of equivalent solute per liter of solution Signup and view all the answers

If you have 0.255 mol of NaOH and the solution has a molarity of 0.125 M, how many liters of solution do you have?

0.875 L Signup and view all the answers

Study Notes

General Chemistry for Pharmaceutical Sciences (PHARM-101)

Course presented by Dr. Azza H. Rageh, Associate Professor of Pharmaceutical Analytical Chemistry at Taibah University
Course covers Stoichiometry, Solution Concentration, and Chemical Reactions
Specifically, the course covers Reaction Stoichiometry, Solution Concentration, and Types of Aqueous Solutions

Stoichiometry

Stoichiometry is the calculation of reactant and product quantities in a chemical reaction
It allows predicting product amounts based on reactant amounts
Also, it calculates the necessary reactants for a desired product amount

Reaction Stoichiometry

Balanced chemical equations show relative amounts (in moles)
Example: 2 C8H18 + 25 O2 → 16 CO2 + 18 H2O
2 moles of C8H18 react with 25 moles of O2 to form 16 moles of CO2 and 18 moles of H2O

Concentration of Solutions

Concentration is the amount of solute in a solution
Units include: percent weight (% w/w), percent volume (% v/v), percent weight per volume (% w/v), parts per million (ppm), parts per billion (ppb), molarity (M), formality (F), normality (N), and molality (m)
Molarity (M) = moles of solute/ liter of solution

Types of Aqueous Solutions

Salt water: homogeneous mixture of NaCl and H₂O
Sugar water: homogeneous mixture of C₁₂H₂₂O₁₁ and H₂O
Solutes dissolve in solvents due to attractive forces

Dissolving Process

Solute particles are attracted to each other
Attractive forces between solvent molecules exist
When mixing, forces between solute and solvent arise
Solute dissolves if these forces are strong enough

Electrolytes and Nonelectrolytes

Electrolytes dissolve in water, forming solutions that conduct electricity
Strong electrolytes fully ionize in water (e.g., ionic salts, strong acids, strong bases)
Weak electrolytes partially ionize (e.g., weak acids, weak bases)
Nonelectrolytes don't ionize (e.g., sugar, alcohol)

Types of Chemical Reactions

Synthesis: two or more reactants combine to form a single product (A + B → AB)
Decomposition: a single compound breaks down into its simpler parts (AB → A + B)
Replacement (Single): a single element replaces another element in a compound (A + BC → AC + B)
Replacement (Double): anions and cations of two compounds swap places (AB + CD → AD + CB)

Chemical Reactions between Ions

Ions combine to form:
- Water
- Weak electrolytes
- Precipitates (insoluble salts)
- Gases
- Complex ions

Acid-Base Reactions (Formation of Water)

Mixing a metallic hydroxide (e.g., NaOH, NH₄OH) with an acid (e.g., HCl) produces water and a salt

Formation of Weak Electrolytes (e.g., Weak Acids)

Mixing a strong acid (e.g., HCl) with a salt containing the anion of a weak acid (e.g. CH₃COONa) produces the weak acid (e.g., CH₃COOH)

Formation of Precipitates

Ions combine to exceed solubility limits—forming an insoluble salt (precipitate)
- Example: AgNO₃ + NaCl → AgCl↓ + NaNO₃

Formation of Gases

Ion combination yields a gas (e.g., H₂S, HCN)

Formation of Complex Ions

Lewis acid (metal) and Lewis base (ligand) react to form a complex
Ligands bond with the metal atom through coordinate bonds
Many cations act as metals and form complexes

Redox Reactions

Redox reactions involve electron transfer
- Oxidation: loss of electrons
- Reduction: gain of electrons
Example: 2 Na(s) + Cl₂(g) → 2 NaCl(s) (Na loses electrons, Cl gains)

Oxidizing and Reducing Agents

Oxidizing agent: substance that oxidizes another (gets reduced)
Reducing agent: substance that reduces another (gets oxidized)

Assessment Questions

Provided multiple examples of different reaction types for calculations and analysis. The questions cover balancing equations, assigning oxidation states, identifying oxidizing/reducing agents, as well as reaction type determination.