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Questions and Answers
Which of the following best describes the difference between a physical and chemical change?
Which of the following best describes the difference between a physical and chemical change?
- A physical change involves energy changes, while a chemical change does not.
- A physical change creates new substances, while a chemical change only alters the appearance.
- A physical change is always reversible, while a chemical change is not.
- A physical change alters the state of a substance, while a chemical change alters its identity. (correct)
Which condition is necessary for reacting particles to cause a chemical reaction, according to collision theory?
Which condition is necessary for reacting particles to cause a chemical reaction, according to collision theory?
- Reacting particles must collide with enough energy. (correct)
- Reacting particles must be in a gaseous state.
- Reacting particles must remain stationary.
- Reacting particles must avoid colliding with each other.
Which of the following does NOT indicate the occurrence of a chemical reaction?
Which of the following does NOT indicate the occurrence of a chemical reaction?
- Change in size. (correct)
- Change in color.
- Release of gas.
- Release of light.
What role does energy play in a chemical reaction regarding the formation of new substances?
What role does energy play in a chemical reaction regarding the formation of new substances?
How does the frequency of collisions affect the rate of a chemical reaction?
How does the frequency of collisions affect the rate of a chemical reaction?
What term describes a solid that suddenly appears as evidence of a chemical reaction?
What term describes a solid that suddenly appears as evidence of a chemical reaction?
Consider a scenario where two chemicals are mixed, but even after colliding, no reaction occurs. Which of the following best explains this?
Consider a scenario where two chemicals are mixed, but even after colliding, no reaction occurs. Which of the following best explains this?
In what part of a chemical reaction is energy change typically observed?
In what part of a chemical reaction is energy change typically observed?
Which of the following describes a change that alters the identity of a substance?
Which of the following describes a change that alters the identity of a substance?
Consider the scent of bread baking in an oven. What type of change is indicated by the odor?
Consider the scent of bread baking in an oven. What type of change is indicated by the odor?
When iron rusts, it combines with oxygen from the air to form iron oxide. Which type of change is this?
When iron rusts, it combines with oxygen from the air to form iron oxide. Which type of change is this?
Dry ice (solid carbon dioxide) sublimates into gaseous carbon dioxide at room temperature. What type of change is this?
Dry ice (solid carbon dioxide) sublimates into gaseous carbon dioxide at room temperature. What type of change is this?
In the context of chemical reactions, what is meant by the 'system'?
In the context of chemical reactions, what is meant by the 'system'?
What effect does increasing the concentration of reactants typically have on the rate of a chemical reaction?
What effect does increasing the concentration of reactants typically have on the rate of a chemical reaction?
Why does increasing the temperature generally speed up chemical reactions?
Why does increasing the temperature generally speed up chemical reactions?
Which of the following processes involves the breaking and forming of chemical bonds?
Which of the following processes involves the breaking and forming of chemical bonds?
How is the release or absorption of heat related to chemical reactions?
How is the release or absorption of heat related to chemical reactions?
A chemist observes that mixing two clear solutions results in a cloudy mixture. What does this suggest?
A chemist observes that mixing two clear solutions results in a cloudy mixture. What does this suggest?
How does the force of collisions relate to whether a chemical reaction occurs?
How does the force of collisions relate to whether a chemical reaction occurs?
When is there unlikely to be a chemical reaction even if reacting particles collide?
When is there unlikely to be a chemical reaction even if reacting particles collide?
Flashcards
Physical Change
Physical Change
Change in a substance that doesn't change its identity.
Chemical Change
Chemical Change
Change of a substance into another substance.
Chemical Reaction
Chemical Reaction
Process by which substances collide with enough energy that new bonds are formed between atoms, creating new substances.
Collision Theory
Collision Theory
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Force in Collision Theory
Force in Collision Theory
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Frequency
Frequency
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Energy Change
Energy Change
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Release of Light
Release of Light
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Temperature Change
Temperature Change
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Precipitate
Precipitate
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Study Notes
- Concept 1 Notes: Writing Reactions
Chemical Reactions
- Physical change: Change in a substance that doesn't change its identity.
- Examples of physical changes: boiling, melting, vaporizing, grinding, etc.
- Chemical change: Change of a substance into another substance, when a chemical reaction occurs.
- Examples of chemical changes: burning, oxidizing, rotting, fermenting, etc.
- Chemical reaction: Process by which substances collide with enough energy that new bonds are formed between atoms, thus creating new substances.
- In a chemical reaction, there is no change in matter.
- In a chemical reaction, there is a change in energy.
Collision Theory
- Reacting particles must collide in order for a chemical reaction to occur.
- Reacting particles must collide with enough force to change something.
- Reacting particles can collide without actually reacting if there isn't enough energy.
- The rate of a chemical reaction depends on the frequency of the collisions.
Evidence of a Chemical Reaction
- When a chemical change occurs, a chemical reaction occurs.
- Energy changes in the system are evidence of a chemical reaction.
- Release of light is evidence of a chemical reaction.
- Heat released or absorbed, leading to a sudden temperature change, is evidence of a chemical reaction.
- Sudden color change is evidence of a chemical reaction.
- Odor change is evidence of a chemical reaction.
- Gas release is evidence of a chemical reaction.
- Sudden appearance of a solid is evidence of a chemical reaction.
- The solid that forms in a chemical reaction is known as a precipitate.
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