Introduction for Reactions - AP Chemistry

What does a large $K$ value indicate about a reaction?

The reaction favors the formation of products. Equilibrium lies far to the right toward products.
What is the formula for the reaction rate?

Reaction rate = $\frac{\text{change in concentration}}{\text{time}}$ . Measures how fast concentration changes over time.
What is the definition of a chemical reaction?

A process where substances convert into different substances. This defines the fundamental nature of chemical change.
What effect does a catalyst have on equilibrium?

A catalyst does not affect the position of equilibrium. Only affects the rate of reaching equilibrium, not position.
What is chemical equilibrium?

A state where the rates of the forward and reverse reactions are equal. Forward and reverse reaction rates are equal at equilibrium.
What does a small $K$ value indicate about a reaction?

The reaction favors the formation of reactants. Equilibrium lies far to the left toward reactants.
What is a balanced chemical equation?

An equation where the number of each type of atom is equal on both sides. Follows the law of conservation of mass.
Which option represents an endothermic reaction?

A reaction that absorbs energy from its surroundings. Products have higher energy than reactants.
What is a coefficient in a chemical equation?

A number in front of a formula indicating the number of molecules. Changes coefficients to balance equations without altering formulas.
What is chemical equilibrium?

A state where the rates of the forward and reverse reactions are equal. Forward and reverse reaction rates are equal at equilibrium.
What is the definition of a chemical reaction?

A process where substances convert into different substances. This defines the fundamental nature of chemical change.
Identify the type of reaction: $2HgO \rightarrow 2Hg + O_2$

Decomposition reaction. One compound breaks down into two or more simpler substances.
Define reduction in terms of electron transfer.

Gain of electrons. Oxidation number decreases when electrons are gained.
What effect does a catalyst have on equilibrium?

A catalyst does not affect the position of equilibrium. Only affects the rate of reaching equilibrium, not position.
Which option represents an exothermic reaction?

A reaction that releases energy, usually in the form of heat. Products have lower energy than reactants.
What is meant by the term 'reactant'?

A starting substance in a chemical reaction. These are the initial materials that undergo transformation.
What is an intermediate in a reaction mechanism?

A species that is formed and consumed during the reaction sequence. Temporary species that appears in mechanism but not overall equation.
Which option represents an exothermic reaction?

A reaction that releases energy, usually in the form of heat. Products have lower energy than reactants.
Identify the symbol for a liquid in chemical equations.

(l). Indicates the substance is in liquid state.
What is chemical equilibrium?

A state where the rates of the forward and reverse reactions are equal. Forward and reverse reaction rates are equal at equilibrium.
What is meant by 'Le Chatelier's Principle'?

If a system at equilibrium is disturbed, the system will shift to counteract the disturbance. System responds to minimize the effect of external changes.
What is a subscript in a chemical formula?

A number indicating the number of atoms of an element in a molecule. Cannot be changed when balancing chemical equations.
Identify the symbol for a solid in chemical equations.

(s). Shows the substance exists in solid state.
Identify the symbol for an aqueous solution in chemical equations.

(aq). Indicates the substance is dissolved in water.
State the law of conservation of mass in reactions.

Mass is conserved; mass of reactants equals mass of products. Atoms cannot be created or destroyed in chemical reactions.
Which option represents an exothermic reaction?

A reaction that releases energy, usually in the form of heat. Products have lower energy than reactants.
What is a subscript in a chemical formula?

A number indicating the number of atoms of an element in a molecule. Cannot be changed when balancing chemical equations.
Define oxidation in terms of electron transfer.

Loss of electrons. Oxidation number increases when electrons are lost.
Identify the type of reaction: $A + BC \rightarrow AC + B$

Single displacement reaction. One element replaces another in a compound.
What does an arrow pointing right signify in a chemical equation?

Represents the direction of the reaction, from reactants to products. Shows the flow of chemical transformation.
What is meant by the term 'reactant'?

A starting substance in a chemical reaction. These are the initial materials that undergo transformation.
Which option represents an endothermic reaction?

A reaction that absorbs energy from its surroundings. Products have higher energy than reactants.
Identify the type of reaction: $NaCl + AgNO_3 \rightarrow NaNO_3 + AgCl$

Double displacement reaction. Two ionic compounds exchange ions to form new compounds.
What does an arrow pointing right signify in a chemical equation?

Represents the direction of the reaction, from reactants to products. Shows the flow of chemical transformation.
What is dynamic equilibrium?

A state where reactants and products are formed at the same rate. Concentrations remain constant but reactions continue occurring.
What is meant by the term 'product' in a reaction?

A substance formed as a result of a chemical reaction. These are the new substances created from reactants.
Identify the symbol for a gas in chemical equations.

(g). Shows the substance exists in gaseous state.
Identify the type of reaction: $A + BC \rightarrow AC + B$

Single displacement reaction. One element replaces another in a compound.
What is meant by the term 'product' in a reaction?

A substance formed as a result of a chemical reaction. These are the new substances created from reactants.
Identify the type of reaction: $A + BC \rightarrow AC + B$

Single displacement reaction. One element replaces another in a compound.
Identify the oxidizing agent in a redox reaction.

The substance that gains electrons. It causes reduction by accepting electrons from another species.
Which factor increases the rate of a reaction?

Increasing temperature, concentration, surface area, or adding a catalyst. These factors increase molecular collisions and energy.
What does a large $K$ value indicate about a reaction?

The reaction favors the formation of products. Equilibrium lies far to the right toward products.
What does a small $K$ value indicate about a reaction?

The reaction favors the formation of reactants. Equilibrium lies far to the left toward reactants.
Identify the symbol for a gas in chemical equations.

(g). Shows the substance exists in gaseous state.
What is meant by the term 'product' in a reaction?

A substance formed as a result of a chemical reaction. These are the new substances created from reactants.
Identify the symbol for a liquid in chemical equations.

(l). Indicates the substance is in liquid state.
Identify the type of reaction: $NaCl + AgNO_3 \rightarrow NaNO_3 + AgCl$

Double displacement reaction. Two ionic compounds exchange ions to form new compounds.
Identify the type of reaction: $2H_2 + O_2 \rightarrow 2H_2O$

Combustion reaction. Hydrocarbon combines with oxygen to form water and carbon dioxide.
What is meant by the term 'reactant'?

A starting substance in a chemical reaction. These are the initial materials that undergo transformation.
What is a balanced chemical equation?

An equation where the number of each type of atom is equal on both sides. Follows the law of conservation of mass.
What is meant by 'reaction mechanism'?

The step-by-step sequence of elementary reactions by which a chemical change occurs. Shows the detailed pathway from reactants to products.
Identify the oxidizing agent in a redox reaction.

The substance that gains electrons. It causes reduction by accepting electrons from another species.
What is an intermediate in a reaction mechanism?

A species that is formed and consumed during the reaction sequence. Temporary species that appears in mechanism but not overall equation.
Identify the symbol for a gas in chemical equations.

(g). Shows the substance exists in gaseous state.
Identify the reducing agent in a redox reaction.

The substance that loses electrons. It causes oxidation by donating electrons to another species.
What is dynamic equilibrium?

A state where reactants and products are formed at the same rate. Concentrations remain constant but reactions continue occurring.
Which factor increases the rate of a reaction?

Increasing temperature, concentration, surface area, or adding a catalyst. These factors increase molecular collisions and energy.
Identify the symbol for an aqueous solution in chemical equations.

(aq). Indicates the substance is dissolved in water.
What is a coefficient in a chemical equation?

A number in front of a formula indicating the number of molecules. Changes coefficients to balance equations without altering formulas.
Identify the symbol for a liquid in chemical equations.

(l). Indicates the substance is in liquid state.
Define the equilibrium constant, $K$ .

A ratio of product concentrations to reactant concentrations at equilibrium. Expressed as $K = \frac{[products]}{[reactants]}$ at constant temperature.
Identify the reducing agent in a redox reaction.

The substance that loses electrons. It causes oxidation by donating electrons to another species.
What is activation energy in a chemical reaction?

The minimum energy required to initiate a reaction. Energy barrier that must be overcome for reaction to proceed.
What does an arrow pointing right signify in a chemical equation?

Represents the direction of the reaction, from reactants to products. Shows the flow of chemical transformation.
Which factor affects the position of equilibrium?

Changes in concentration, temperature, or pressure. These external changes shift equilibrium to relieve stress.
What is meant by 'reaction mechanism'?

The step-by-step sequence of elementary reactions by which a chemical change occurs. Shows the detailed pathway from reactants to products.
State the role of a catalyst in a chemical reaction.

A substance that increases reaction rate without being consumed. Lowers activation energy by providing alternative pathway.
What does a small $K$ value indicate about a reaction?

The reaction favors the formation of reactants. Equilibrium lies far to the left toward reactants.
What does a large $K$ value indicate about a reaction?

The reaction favors the formation of products. Equilibrium lies far to the right toward products.
Which factor affects the position of equilibrium?

Changes in concentration, temperature, or pressure. These external changes shift equilibrium to relieve stress.
What is an oxidation-reduction (redox) reaction?

A reaction where electrons are transferred between substances. Involves changes in oxidation states of elements.
Identify the symbol for an aqueous solution in chemical equations.

(aq). Indicates the substance is dissolved in water.
Identify the type of reaction: $2Na + Cl_2 \rightarrow 2NaCl$

Synthesis reaction. Two or more simple substances combine to form one compound.
What is a coefficient in a chemical equation?

A number in front of a formula indicating the number of molecules. Changes coefficients to balance equations without altering formulas.
What is meant by 'Le Chatelier's Principle'?

If a system at equilibrium is disturbed, the system will shift to counteract the disturbance. System responds to minimize the effect of external changes.
Identify the type of reaction: $2HgO \rightarrow 2Hg + O_2$

Decomposition reaction. One compound breaks down into two or more simpler substances.
What is the definition of a chemical reaction?

A process where substances convert into different substances. This defines the fundamental nature of chemical change.
What is an intermediate in a reaction mechanism?

A species that is formed and consumed during the reaction sequence. Temporary species that appears in mechanism but not overall equation.
Define reduction in terms of electron transfer.

Gain of electrons. Oxidation number decreases when electrons are gained.
What is an oxidation-reduction (redox) reaction?

A reaction where electrons are transferred between substances. Involves changes in oxidation states of elements.
Identify the type of reaction: $2HgO \rightarrow 2Hg + O_2$

Decomposition reaction. One compound breaks down into two or more simpler substances.
What is an oxidation-reduction (redox) reaction?

A reaction where electrons are transferred between substances. Involves changes in oxidation states of elements.
Which factor increases the rate of a reaction?

Increasing temperature, concentration, surface area, or adding a catalyst. These factors increase molecular collisions and energy.
Define the equilibrium constant, $K$ .

A ratio of product concentrations to reactant concentrations at equilibrium. Expressed as $K = \frac{[products]}{[reactants]}$ at constant temperature.
What is a balanced chemical equation?

An equation where the number of each type of atom is equal on both sides. Follows the law of conservation of mass.
Identify the oxidizing agent in a redox reaction.

The substance that gains electrons. It causes reduction by accepting electrons from another species.
What is meant by 'Le Chatelier's Principle'?

If a system at equilibrium is disturbed, the system will shift to counteract the disturbance. System responds to minimize the effect of external changes.
State the collision theory of chemical reactions.

Reactions occur when particles collide with sufficient energy and proper orientation. Explains why reaction rate depends on concentration and temperature.
Which factor affects the position of equilibrium?

Changes in concentration, temperature, or pressure. These external changes shift equilibrium to relieve stress.
What is a subscript in a chemical formula?

A number indicating the number of atoms of an element in a molecule. Cannot be changed when balancing chemical equations.
What is activation energy in a chemical reaction?

The minimum energy required to initiate a reaction. Energy barrier that must be overcome for reaction to proceed.
Which option represents an endothermic reaction?

A reaction that absorbs energy from its surroundings. Products have higher energy than reactants.
State the law of conservation of mass in reactions.

Mass is conserved; mass of reactants equals mass of products. Atoms cannot be created or destroyed in chemical reactions.
State the collision theory of chemical reactions.

Reactions occur when particles collide with sufficient energy and proper orientation. Explains why reaction rate depends on concentration and temperature.
State the role of a catalyst in a chemical reaction.

A substance that increases reaction rate without being consumed. Lowers activation energy by providing alternative pathway.
What is activation energy in a chemical reaction?

The minimum energy required to initiate a reaction. Energy barrier that must be overcome for reaction to proceed.
State the role of a catalyst in a chemical reaction.

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

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