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Questions and Answers
Which of the following best describes the law of conservation of mass in the context of chemical reactions?
Which of the following best describes the law of conservation of mass in the context of chemical reactions?
- Mass within an isolated system can be transformed from one form to another, but the total mass remains constant. (correct)
- Mass is always lost during a chemical reaction due to energy release.
- The total mass of reactants is less than the total mass of products in any chemical reaction.
- Mass is only conserved in reactions that do not involve gases.
In a double displacement reaction, what is the primary characteristic that defines this type of chemical change?
In a double displacement reaction, what is the primary characteristic that defines this type of chemical change?
- One element replaces another in a compound.
- Reactant ions exchange places to form new products. (correct)
- A compound breaks down into two or more simpler substances.
- A substance reacts with oxygen to produce light and heat.
Which of the following is a key difference between a physical change and a chemical change?
Which of the following is a key difference between a physical change and a chemical change?
- Physical changes always produce gases, while chemical changes never do.
- Physical changes always involve a change in color, while chemical changes do not.
- In a physical change, the type of matter stays the same, while in a chemical change, the type of matter changes. (correct)
- Chemical changes are easily reversible, while physical changes are not.
What role does 'activation energy' play in a chemical reaction according to the collision theory?
What role does 'activation energy' play in a chemical reaction according to the collision theory?
How does an increase in temperature typically affect the rate of a chemical reaction, and why?
How does an increase in temperature typically affect the rate of a chemical reaction, and why?
Consider the reaction: $2Mg + O_2 \rightarrow 2MgO$. What type of reaction is this?
Consider the reaction: $2Mg + O_2 \rightarrow 2MgO$. What type of reaction is this?
In what way does a catalyst increase the rate of a chemical reaction?
In what way does a catalyst increase the rate of a chemical reaction?
How does increasing the concentration of reactants in a solution typically affect the rate of a chemical reaction?
How does increasing the concentration of reactants in a solution typically affect the rate of a chemical reaction?
Which of the following is an example of a physical change?
Which of the following is an example of a physical change?
Consider the reaction: $Zn + 2HCl \rightarrow ZnCl_2 + H_2$. What type of reaction is this?
Consider the reaction: $Zn + 2HCl \rightarrow ZnCl_2 + H_2$. What type of reaction is this?
Balancing chemical equations is essential to adhere to which fundamental law?
Balancing chemical equations is essential to adhere to which fundamental law?
Which factor directly affects the frequency of collisions between reactant particles?
Which factor directly affects the frequency of collisions between reactant particles?
What type of reaction is generally associated with the release of energy in the form of light and heat?
What type of reaction is generally associated with the release of energy in the form of light and heat?
Consider the reaction: $Pb(NO_3)_2 \rightarrow PbO + NO_2 + O_2$. What type of reaction is this?
Consider the reaction: $Pb(NO_3)_2 \rightarrow PbO + NO_2 + O_2$. What type of reaction is this?
In what state must reactants be in order for concentration to affect the rate of reaction?
In what state must reactants be in order for concentration to affect the rate of reaction?
How does increasing the surface area of a solid reactant typically affect the rate of a chemical reaction, and why?
How does increasing the surface area of a solid reactant typically affect the rate of a chemical reaction, and why?
During a chemical reaction, what happens to a catalyst?
During a chemical reaction, what happens to a catalyst?
In the reaction: $CH_4 + O_2 \rightarrow CO_2 + H_2O + energy$, what type of reaction is occurring?
In the reaction: $CH_4 + O_2 \rightarrow CO_2 + H_2O + energy$, what type of reaction is occurring?
Why is it important to balance chemical equations?
Why is it important to balance chemical equations?
Which category of elements are most commonly used as catalysts?
Which category of elements are most commonly used as catalysts?
Flashcards
Physical Change
Physical Change
Type of change where the matter's composition remains the same; no new chemical is formed.
Chemical Change
Chemical Change
Type of change where the matter transforms into a new substance.
Law of Conservation of Mass
Law of Conservation of Mass
The principle stating that mass is conserved in a closed system; it cannot be created nor destroyed.
Synthesis Reaction
Synthesis Reaction
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Single Displacement Reaction
Single Displacement Reaction
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Double Displacement Reaction
Double Displacement Reaction
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Decomposition Reaction
Decomposition Reaction
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Combustion Reaction
Combustion Reaction
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Activation Energy
Activation Energy
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Frequency of Collisions
Frequency of Collisions
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Temperature
Temperature
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Concentration/Pressure
Concentration/Pressure
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Surface Area
Surface Area
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Catalyst
Catalyst
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Study Notes
- Physical changes: The type of matter remains the same, and a new substance or chemical is not formed.
- Example: Blow-drying wet hair.
- Chemical changes: The type of matter changes, resulting in the formation of one or more new substances.
- Example: A bicycle rusting, which changes color.
Why Balance Equations?
- It is important to balance chemical equations to adhere to the law of conservation of mass.
- Law of conservation of mass: The mass in an isolated system remains constant over time, it can neither be created nor destroyed but can be transformed from one form to another.
- Based on this law, the mass of the reactants in a chemical reaction must be equal to the mass of the products, particularly in a low-energy thermodynamic process.
Different Types of Reactions
- Synthesis: Combines multiple reactants to form a single product.
- Example: 2Mg + O2 → 2MgO
- Single Displacement: One element replaces another in a compound.
- Example: Zn + HCl → ZnCl2 + H2
- Double Displacement: Reactant ions (cations and anions) exchange places, leading to the formation of new products.
- Example: KI + Pb(NO3)2 → PbI2 + KNO3
- Decomposition: A compound breaks down into two or more simpler substances or products.
- Example: Pb(NO3)2 → PbO + NO2
- Release of gas.
- Example: Pb(NO3)2 → PbO + NO2
- Combustion: A substance reacts with oxygen gas to produce energy in the form of light and heat.
- Example: CH4 + O2 → CO2 + H2O → energy
Factors Affecting Rate of Reaction
- Collision theory: Particles must collide with enough energy for a reaction to occur. This energy is called activation energy. Without sufficient energy upon collision, no reaction happens.
- Amount of energy: The more energy the particles possess, the more they can transfer during a collision.
- Frequency of collisions: Refers to how often particles collide.
- More frequent collisions lead to a higher chance of a successful reaction.
Factors
- Temperature: As temperature increases, particles gain more energy, move faster, and collide more frequently.
- This increases the likelihood of exceeding the activation energy, resulting in a higher rate of successful reactions.
- Directly proportional: Temperature (+) = Rate of reaction (+)
- Concentration (liquid solutions)/Pressure (gases): Refers to the number of particles present per unit volume.
- If concentration or pressure increases, more particles per unit of volume are formed, leading to more frequent collisions and an increased rate of reaction.
- Directly proportional: Concentration/pressure (+) = Rate of reaction (+)
- Surface Area: A higher surface area results in a higher rate of reaction.
- Surface Area (+) → results in higher rate of reaction (+)
- Catalyst: Substances that accelerate a reaction without being consumed in the process.
- They lower the activation energy by providing alternative energy pathways, leading to a higher proportion of successful collisions.
- Common catalysts: transition metals and enzymes.
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