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Molarity
Preparing a solution
Dilution
Solubility rules
Complete & Net Ionic Equations
Colligative properties
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Heat Flow
Energy diagrams
Thermochemical equations
Heating/ Cooling curves
Specific Heat Capacity
Calorimetry
Hess's Law
Enthalpies of formation
Bond enthalpies
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Collision Theory
Rate Comparisons
Integrated Rate Law
Differential Rate Law
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Equilibrium
Equilibrium Expression
ICE Tables
Calculating K
K vs Q
Le Chatelier's Principle
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Definitions
Conjugate Acids & Base Pairs
Autoionization of water
pH Scale
Strong Acids/ Bases
Ka and Kb
Buffer
Titrations
Indicators
pH salts
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Entropy
Gibb's Free Energy
G and Temperature
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Oxidation numbers
Half Reactions
Balancing Redox reactions
Voltaic cells
Cell potential (standard conditions)
Cell potential (non-standard)
Electrolysis
Quantitative Electrochemistry
Gas Laws
Related Examples and Practice Problems
Additional Worked Out Examples/ Practice
Identifying classification types: Differentiation between elements, compounds or mixtures and homogeneous and heterogenous mixtures
Separation techniques: Selected and explaining limitation of appropriate separation
Relating Properties to Composition: Predicting classification based on descriptive properties
and more …
Topic Summary & Highlights
and Help Videos
Core Concept
The gas laws describe how gases respond to changes in pressure, volume, and temperature. These relationships are crucial for predicting and understanding gas behavior under different conditions.
Key Terms
Pressure (P): The force that gas particles exert on the walls of their container; typically measured in units like atmospheres (atm), kilopascals (kPa), or millimeters of mercury (mmHg).
Volume (V): The amount of space a gas occupies, usually measured in liters (L) or milliliters (mL).
Temperature (T): A measure of the average kinetic energy of gas particles; always use the Kelvin scale in gas law calculations.
Moles (n): The amount of gas, measured in moles (mol).
| Gas Law | Relationship | Equation | Explanation | Graph |
|---|---|---|---|---|
| Boyle’s Law | Pressure-Volume | ( $P_1 V_1$ = $P_2 V_2$ ) | At constant temperature, the volume of a gas is inversely proportional to its pressure. | Hyperbolic curve for ( P ) vs. ( V ) |
| Charles’s Law | Volume-Temperature | ( $\frac{V_1}{T_1}$ = $\frac{V_2}{T_2}$ ) | At constant pressure, the volume of a gas is directly proportional to its temperature (Kelvin). | Straight line for ( V ) vs. ( T ) (K) |
| Gay-Lussac’s Law | Pressure-Temperature | \( $\frac{P_1}{T_1}$ = $\frac{P_2}{T_2}$ ) | At constant volume, the pressure of a gas is directly proportional to its temperature (Kelvin). | Straight line for ( P ) vs. ( T ) (K) |
| Avogadro’s Law | Volume-Mole | ( $\frac{V_1}{n_1}$ = $\frac{V_2}{n_2}$ ) | At constant temperature and pressure, the volume of a gas is directly proportional to the moles of gas. | Straight line for ( V ) vs. ( n ) |
| Combined Gas Law | Pressure-Volume-Temperature | ( $\frac{P_1 V_1}{T_1}$ = $\frac{P_2 V_2}{T_2}$ ) | Combines Boyle’s, Charles’s, and Gay-Lussac’s laws to relate changes in ( P ), ( V ), and \( T \) when the amount of gas is constant. | N/A |
Example problems Applying the Gas Laws
| Gas Law | Example Problem | Solution |
|---|---|---|
| Boyle’s Law | If you have a gas at 1.5 atm pressure and a volume of 2.0 L, what will the volume be if the pressure increases to 3.0 atm at constant temperature? | Use \( P_1 V_1 = P_2 V_2 \): \( (1.5 \, \text{atm})(2.0 \, \text{L}) = (3.0 \, \text{atm})(V_2) \) \( V_2 = \frac{(1.5)(2.0)}{3.0} = 1.0 \, \text{L} \) |
| Charles’s Law | A gas occupies 3.0 L at 273 K. What will the volume be at 546 K if pressure is constant? | Use \( \frac{V_1}{T_1} = \frac{V_2}{T_2} \): \( \frac{3.0 \, \text{L}}{273 \, \text{K}} = \frac{V_2}{546 \, \text{K}} \) \( V_2 = \frac{3.0 \times 546}{273} = 6.0 \, \text{L} \) |
| Gay-Lussac’s Law | A gas at 1.0 atm and 300 K is heated to 600 K at constant volume. What is the final pressure? | Use \( \frac{P_1}{T_1} = \frac{P_2}{T_2} \): \( \frac{1.0 \, \text{atm}}{300 \, \text{K}} = \frac{P_2}{600 \, \text{K}} \) \( P_2 = \frac{(1.0)(600)}{300} = 2.0 \, \text{atm} \) |
| Avogadro’s Law | If 2.0 mol of a gas occupies 10.0 L, what volume will 5.0 mol of gas occupy at the same temperature and pressure? | Use \( \frac{V_1}{n_1} = \frac{V_2}{n_2} \): \( \frac{10.0 \, \text{L}}{2.0 \, \text{mol}} = \frac{V_2}{5.0 \, \text{mol}} \) \( V_2 = \frac{(10.0)(5.0)}{2.0} = 25.0 \, \text{L} \) |
| Combined Gas Law | A gas has an initial volume of 5.0 L at 1.0 atm and 300 K. What will the volume be if the pressure is increased to 2.0 atm and the temperature raised to 400 K? | Use \( \frac{P_1 V_1}{T_1} = \frac{P_2 V_2}{T_2} \): \( \frac{(1.0)(5.0)}{300} = \frac{(2.0)(V_2)}{400} \) \( V_2 = \frac{(1.0)(5.0)(400)}{(2.0)(300)} = 3.33 \, \text{L} \) |
Tips for Using the Gas Laws
Convert Temperature to Kelvin: Always use Kelvin for temperature when working with gas laws.
Be Consistent with Units: Make sure pressure and volume units match, especially if converting between units like atm, kPa, or mmHg.
Direct vs. Inverse Relationships:
Boyle’s Law (pressure and volume) is an inverse relationship: as one increases, the other decreases.
Charles’s, Gay-Lussac’s, and Avogadro’s Laws all show direct relationships: as one variable increases, so does the other.
Know When to Use Each Law: Determine which variables are held constant and which are changing to decide which gas law to apply.
