AP Chemistry Flashcards: Introduction For Reactions

What this deck covers

This deck focuses on Introduction For Reactions, giving you a quick way to review the definitions, rules, and examples that matter most for AP Chemistry.

How to use these flashcards

Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: What does a large $K$ value indicate about a reaction?

Answer: The reaction favors the formation of products. Equilibrium lies far to the right toward products.

Flashcard 2: What is the formula for the reaction rate?

Answer: Reaction rate = $\frac{\text{change in concentration}}{\text{time}}$. Measures how fast concentration changes over time.

Flashcard 3: What is the definition of a chemical reaction?

Answer: A process where substances convert into different substances. This defines the fundamental nature of chemical change.

Flashcard 4: What effect does a catalyst have on equilibrium?

Answer: A catalyst does not affect the position of equilibrium. Only affects the rate of reaching equilibrium, not position.

Flashcard 5: What is chemical equilibrium?

Answer: A state where the rates of the forward and reverse reactions are equal. Forward and reverse reaction rates are equal at equilibrium.

Flashcard 6: What does a small $K$ value indicate about a reaction?

Answer: The reaction favors the formation of reactants. Equilibrium lies far to the left toward reactants.

Flashcard 7: What is a balanced chemical equation?

Answer: An equation where the number of each type of atom is equal on both sides. Follows the law of conservation of mass.

Flashcard 8: Which option represents an endothermic reaction?

Answer: A reaction that absorbs energy from its surroundings. Products have higher energy than reactants.

Flashcard 9: What is a coefficient in a chemical equation?

Answer: A number in front of a formula indicating the number of molecules. Changes coefficients to balance equations without altering formulas.

Flashcard 10: What is chemical equilibrium?

Answer: A state where the rates of the forward and reverse reactions are equal. Forward and reverse reaction rates are equal at equilibrium.

Flashcard 11: What is the definition of a chemical reaction?

Answer: A process where substances convert into different substances. This defines the fundamental nature of chemical change.

Flashcard 12: Identify the type of reaction: $2HgO \rightarrow 2Hg + O_2$

Answer: Decomposition reaction. One compound breaks down into two or more simpler substances.

Flashcard 13: Define reduction in terms of electron transfer.

Answer: Gain of electrons. Oxidation number decreases when electrons are gained.

Flashcard 14: What effect does a catalyst have on equilibrium?

Answer: A catalyst does not affect the position of equilibrium. Only affects the rate of reaching equilibrium, not position.

Flashcard 15: Which option represents an exothermic reaction?

Answer: A reaction that releases energy, usually in the form of heat. Products have lower energy than reactants.

Flashcard 16: What is meant by the term 'reactant'?

Answer: A starting substance in a chemical reaction. These are the initial materials that undergo transformation.

Flashcard 17: What is an intermediate in a reaction mechanism?

Answer: A species that is formed and consumed during the reaction sequence. Temporary species that appears in mechanism but not overall equation.

Flashcard 18: Which option represents an exothermic reaction?

Answer: A reaction that releases energy, usually in the form of heat. Products have lower energy than reactants.

Flashcard 19: Identify the symbol for a liquid in chemical equations.

Answer: (l). Indicates the substance is in liquid state.

Flashcard 20: What is chemical equilibrium?

Answer: A state where the rates of the forward and reverse reactions are equal. Forward and reverse reaction rates are equal at equilibrium.

Flashcard 21: What is meant by 'Le Chatelier's Principle'?

Answer: If a system at equilibrium is disturbed, the system will shift to counteract the disturbance. System responds to minimize the effect of external changes.

Flashcard 22: What is a subscript in a chemical formula?

Answer: A number indicating the number of atoms of an element in a molecule. Cannot be changed when balancing chemical equations.

Flashcard 23: Identify the symbol for a solid in chemical equations.

Answer: (s). Shows the substance exists in solid state.

Flashcard 24: Identify the symbol for an aqueous solution in chemical equations.

Answer: (aq). Indicates the substance is dissolved in water.

Flashcard 25: State the law of conservation of mass in reactions.

Answer: Mass is conserved; mass of reactants equals mass of products. Atoms cannot be created or destroyed in chemical reactions.

Flashcard 26: Which option represents an exothermic reaction?

Answer: A reaction that releases energy, usually in the form of heat. Products have lower energy than reactants.

Flashcard 27: What is a subscript in a chemical formula?

Answer: A number indicating the number of atoms of an element in a molecule. Cannot be changed when balancing chemical equations.

Flashcard 28: Define oxidation in terms of electron transfer.

Answer: Loss of electrons. Oxidation number increases when electrons are lost.

Flashcard 29: Identify the type of reaction: $A + BC \rightarrow AC + B$

Answer: Single displacement reaction. One element replaces another in a compound.

Flashcard 30: What does an arrow pointing right signify in a chemical equation?

Answer: Represents the direction of the reaction, from reactants to products. Shows the flow of chemical transformation.

Flashcard 31: What is meant by the term 'reactant'?

Answer: A starting substance in a chemical reaction. These are the initial materials that undergo transformation.

Flashcard 32: Which option represents an endothermic reaction?

Answer: A reaction that absorbs energy from its surroundings. Products have higher energy than reactants.

Flashcard 33: Identify the type of reaction: $NaCl + AgNO_3 \rightarrow NaNO_3 + AgCl$

Answer: Double displacement reaction. Two ionic compounds exchange ions to form new compounds.

Flashcard 34: What does an arrow pointing right signify in a chemical equation?

Answer: Represents the direction of the reaction, from reactants to products. Shows the flow of chemical transformation.

Flashcard 35: What is dynamic equilibrium?

Answer: A state where reactants and products are formed at the same rate. Concentrations remain constant but reactions continue occurring.

Flashcard 36: What is meant by the term 'product' in a reaction?

Answer: A substance formed as a result of a chemical reaction. These are the new substances created from reactants.

Flashcard 37: Identify the symbol for a gas in chemical equations.

Answer: (g). Shows the substance exists in gaseous state.

Flashcard 38: Identify the type of reaction: $A + BC \rightarrow AC + B$

Answer: Single displacement reaction. One element replaces another in a compound.

Flashcard 39: What is meant by the term 'product' in a reaction?

Answer: A substance formed as a result of a chemical reaction. These are the new substances created from reactants.

Flashcard 40: Identify the type of reaction: $A + BC \rightarrow AC + B$

Answer: Single displacement reaction. One element replaces another in a compound.

Flashcard 41: Identify the oxidizing agent in a redox reaction.

Answer: The substance that gains electrons. It causes reduction by accepting electrons from another species.

Flashcard 42: Which factor increases the rate of a reaction?

Answer: Increasing temperature, concentration, surface area, or adding a catalyst. These factors increase molecular collisions and energy.

Flashcard 43: What does a large $K$ value indicate about a reaction?

Answer: The reaction favors the formation of products. Equilibrium lies far to the right toward products.

Flashcard 44: What does a small $K$ value indicate about a reaction?

Answer: The reaction favors the formation of reactants. Equilibrium lies far to the left toward reactants.

Flashcard 45: Identify the symbol for a gas in chemical equations.

Answer: (g). Shows the substance exists in gaseous state.

Flashcard 46: What is meant by the term 'product' in a reaction?

Answer: A substance formed as a result of a chemical reaction. These are the new substances created from reactants.

Flashcard 47: Identify the symbol for a liquid in chemical equations.

Answer: (l). Indicates the substance is in liquid state.

Flashcard 48: Identify the type of reaction: $NaCl + AgNO_3 \rightarrow NaNO_3 + AgCl$

Answer: Double displacement reaction. Two ionic compounds exchange ions to form new compounds.

Flashcard 49: Identify the type of reaction: $2H_2 + O_2 \rightarrow 2H_2O$

Answer: Combustion reaction. Hydrocarbon combines with oxygen to form water and carbon dioxide.

Flashcard 50: What is meant by the term 'reactant'?

Answer: A starting substance in a chemical reaction. These are the initial materials that undergo transformation.

Flashcard 51: What is a balanced chemical equation?

Answer: An equation where the number of each type of atom is equal on both sides. Follows the law of conservation of mass.

Flashcard 52: What is meant by 'reaction mechanism'?

Answer: The step-by-step sequence of elementary reactions by which a chemical change occurs. Shows the detailed pathway from reactants to products.

Flashcard 53: Identify the oxidizing agent in a redox reaction.

Answer: The substance that gains electrons. It causes reduction by accepting electrons from another species.

Flashcard 54: What is an intermediate in a reaction mechanism?

Answer: A species that is formed and consumed during the reaction sequence. Temporary species that appears in mechanism but not overall equation.

Flashcard 55: Identify the symbol for a gas in chemical equations.

Answer: (g). Shows the substance exists in gaseous state.

Flashcard 56: Identify the reducing agent in a redox reaction.

Answer: The substance that loses electrons. It causes oxidation by donating electrons to another species.

Flashcard 57: What is dynamic equilibrium?

Answer: A state where reactants and products are formed at the same rate. Concentrations remain constant but reactions continue occurring.

Flashcard 58: Which factor increases the rate of a reaction?

Answer: Increasing temperature, concentration, surface area, or adding a catalyst. These factors increase molecular collisions and energy.

Flashcard 59: Identify the symbol for an aqueous solution in chemical equations.

Answer: (aq). Indicates the substance is dissolved in water.

Flashcard 60: What is a coefficient in a chemical equation?

Answer: A number in front of a formula indicating the number of molecules. Changes coefficients to balance equations without altering formulas.

Flashcard 61: Identify the symbol for a liquid in chemical equations.

Answer: (l). Indicates the substance is in liquid state.

Flashcard 62: Define the equilibrium constant, $K$.

Answer: A ratio of product concentrations to reactant concentrations at equilibrium. Expressed as $K = \frac{[products]}{[reactants]}$ at constant temperature.

Flashcard 63: Identify the reducing agent in a redox reaction.

Answer: The substance that loses electrons. It causes oxidation by donating electrons to another species.

Flashcard 64: What is activation energy in a chemical reaction?

Answer: The minimum energy required to initiate a reaction. Energy barrier that must be overcome for reaction to proceed.

Flashcard 65: What does an arrow pointing right signify in a chemical equation?

Answer: Represents the direction of the reaction, from reactants to products. Shows the flow of chemical transformation.

Flashcard 66: Which factor affects the position of equilibrium?

Answer: Changes in concentration, temperature, or pressure. These external changes shift equilibrium to relieve stress.

Flashcard 67: What is meant by 'reaction mechanism'?

Answer: The step-by-step sequence of elementary reactions by which a chemical change occurs. Shows the detailed pathway from reactants to products.

Flashcard 68: State the role of a catalyst in a chemical reaction.

Answer: A substance that increases reaction rate without being consumed. Lowers activation energy by providing alternative pathway.

Flashcard 69: What does a small $K$ value indicate about a reaction?

Answer: The reaction favors the formation of reactants. Equilibrium lies far to the left toward reactants.

Flashcard 70: What does a large $K$ value indicate about a reaction?

Answer: The reaction favors the formation of products. Equilibrium lies far to the right toward products.

Flashcard 71: Which factor affects the position of equilibrium?

Answer: Changes in concentration, temperature, or pressure. These external changes shift equilibrium to relieve stress.

Flashcard 72: What is an oxidation-reduction (redox) reaction?

Answer: A reaction where electrons are transferred between substances. Involves changes in oxidation states of elements.

Flashcard 73: Identify the symbol for an aqueous solution in chemical equations.

Answer: (aq). Indicates the substance is dissolved in water.

Flashcard 74: Identify the type of reaction: $2Na + Cl_2 \rightarrow 2NaCl$

Answer: Synthesis reaction. Two or more simple substances combine to form one compound.

Flashcard 75: What is a coefficient in a chemical equation?

Answer: A number in front of a formula indicating the number of molecules. Changes coefficients to balance equations without altering formulas.

Flashcard 76: What is meant by 'Le Chatelier's Principle'?

Answer: If a system at equilibrium is disturbed, the system will shift to counteract the disturbance. System responds to minimize the effect of external changes.

Flashcard 77: Identify the type of reaction: $2HgO \rightarrow 2Hg + O_2$

Answer: Decomposition reaction. One compound breaks down into two or more simpler substances.

Flashcard 78: What is the definition of a chemical reaction?

Answer: A process where substances convert into different substances. This defines the fundamental nature of chemical change.

Flashcard 79: What is an intermediate in a reaction mechanism?

Answer: A species that is formed and consumed during the reaction sequence. Temporary species that appears in mechanism but not overall equation.

Flashcard 80: Define reduction in terms of electron transfer.

Answer: Gain of electrons. Oxidation number decreases when electrons are gained.

Flashcard 81: What is an oxidation-reduction (redox) reaction?

Answer: A reaction where electrons are transferred between substances. Involves changes in oxidation states of elements.

Flashcard 82: Identify the type of reaction: $2HgO \rightarrow 2Hg + O_2$

Answer: Decomposition reaction. One compound breaks down into two or more simpler substances.

Flashcard 83: What is an oxidation-reduction (redox) reaction?

Answer: A reaction where electrons are transferred between substances. Involves changes in oxidation states of elements.

Flashcard 84: Which factor increases the rate of a reaction?

Answer: Increasing temperature, concentration, surface area, or adding a catalyst. These factors increase molecular collisions and energy.

Flashcard 85: Define the equilibrium constant, $K$.

Answer: A ratio of product concentrations to reactant concentrations at equilibrium. Expressed as $K = \frac{[products]}{[reactants]}$ at constant temperature.

Flashcard 86: What is a balanced chemical equation?

Answer: An equation where the number of each type of atom is equal on both sides. Follows the law of conservation of mass.

Flashcard 87: Identify the oxidizing agent in a redox reaction.

Answer: The substance that gains electrons. It causes reduction by accepting electrons from another species.

Flashcard 88: What is meant by 'Le Chatelier's Principle'?

Answer: If a system at equilibrium is disturbed, the system will shift to counteract the disturbance. System responds to minimize the effect of external changes.

Flashcard 89: State the collision theory of chemical reactions.

Answer: Reactions occur when particles collide with sufficient energy and proper orientation. Explains why reaction rate depends on concentration and temperature.

Flashcard 90: Which factor affects the position of equilibrium?

Answer: Changes in concentration, temperature, or pressure. These external changes shift equilibrium to relieve stress.

Flashcard 91: What is a subscript in a chemical formula?

Answer: A number indicating the number of atoms of an element in a molecule. Cannot be changed when balancing chemical equations.

Flashcard 92: What is activation energy in a chemical reaction?

Answer: The minimum energy required to initiate a reaction. Energy barrier that must be overcome for reaction to proceed.

Flashcard 93: Which option represents an endothermic reaction?

Answer: A reaction that absorbs energy from its surroundings. Products have higher energy than reactants.

Flashcard 94: State the law of conservation of mass in reactions.

Answer: Mass is conserved; mass of reactants equals mass of products. Atoms cannot be created or destroyed in chemical reactions.

Flashcard 95: State the collision theory of chemical reactions.

Answer: Reactions occur when particles collide with sufficient energy and proper orientation. Explains why reaction rate depends on concentration and temperature.

Flashcard 96: State the role of a catalyst in a chemical reaction.

Answer: A substance that increases reaction rate without being consumed. Lowers activation energy by providing alternative pathway.

Flashcard 97: What is activation energy in a chemical reaction?

Answer: The minimum energy required to initiate a reaction. Energy barrier that must be overcome for reaction to proceed.

Flashcard 98: State the role of a catalyst in a chemical reaction.

Answer: A substance that increases reaction rate without being consumed. Lowers activation energy by providing alternative pathway.