What is a physical change?

A physical change is a change that does not produce any new chemical substances and is often easy to reverse.

What is a chemical change?

A chemical change is a change where new chemical substances are formed, often with very different properties from the reactants.

True or False? Physical changes are difficult to reverse.

False. Physical changes are often easy to reverse.

What indicates a chemical change has occurred?

Signs of a chemical change include colour changes, temperature changes, and effervescence (fizzing).

What is effervescence ?

Effervescence is the rapid escape of gas from a liquid in which it is dissolved, causing fizzing.

What colour change occurs in the metal displacement reaction of silver nitrate and copper?

The solid changes from orange-brown to silver, and the solution changes from colourless to blue.

State one example of a physical change.

One example of a physical change could be: Melting (solid to liquid) Making a mixture from 2 or more substances Dissolving a solute in a solvent

True or False? A change in pH is an indication of a physical change.

False. A change in pH is an indication of a chemical change.

True or False? Dissolving a solute in a solvent is a chemical change.

False. Dissolving a solute in a solvent is a physical change.

State the two types of reactions that cause a change in temperature.

The two types of reactions that cause a change in temperature are: Those that give out heat / thermal energy - exothermic Those that take in heat / thermal energy - endothermic

What has a greater surface area, magnesium ribbon or magnesium powder?

Magnesium powder has a greater surface area.

What four factors affect the rate of a chemical reaction?

The four factors that can affect the rate of a reaction are: The concentration of the reactants in solution or the pressure of reacting gases Surface area of solid reactants The temperature of the reaction The presence of a catalyst

Which graph will have a steeper gradient? Concentrated acid and marble chips or dilute acid and marble chips?

The graph which will have the steeper gradient is concentrated acid and marble chips.

A steep gradient on a rate of reaction graph indicates ........

A steep gradient on a rate of reaction graph indicates a fast rate of reaction.

Will increasing or decreasing the temperature increase the rate of reaction?

Increasing the temperature will increase the rate of reaction.

True or False? Adding a catalyst to a reaction will decrease the rate.

False. Adding a catalyst to a reaction will increase the rate.

True or False? It is of economic interest to have a higher rate of reaction as this implies a higher rate of production and hence a more efficient and sustainable process.

True. It is of economic interest to have a higher rate of reaction as this implies a higher rate of production and hence a more efficient and sustainable process.

Define the term collision theory . (Extended Tier Only)

A theory that explains how rates of reaction depend on the frequency and energy of collisions between reactant particles.

True or False? All collisions result in a chemical reaction. (Extended Tier Only)

False. Not all collisions result in a chemical reaction. Unsuccessful collisions happen when the colliding species do not have enough energy to break the necessary bonds.

State the relationship between the number of collisions and the number of particles. (Extended Tier Only)

The number of collisions is proportional to the number of particles present.

Define the term successful collision . (Extended Tier Only)

A successful collision is a collision between reactant particles that leads to the formation of product molecules.

What role does orientation play in collision theory? (Extended Tier Only)

Correct orientation is required for reacting particles to collide effectively and form products.

What is an unsuccessful collision? (Extended Tier Only)

An unsuccessful collision is one in which the reactant particles just bounce off each other and remain unchanged.

Define activation energy . (Extended Tier Only)

Activation energy is the minimum energy that reacting particles must have for a reaction to occur.

How does the increasing the kinetic energy of the particles affect the number of successful collisions? (Extended Tier Only)

Greater kinetic energy means a greater proportion of collisions will have an energy that exceeds the activation energy. There are more frequent collisions as the particles are moving quicker. Therefore, more collisions will be successful.

What factors affect the rate of reaction? (Extended Tier Only)

Factors affecting the rate of reaction include temperature, concentration, surface area, and the presence of a catalyst.

Define the term activation energy . (Extended Tier Only)

The minimum energy required for reactant particles to undergo a chemical reaction.

True or False? Increasing concentration increases the number of collisions per second. (Extended Tier Only)

True. Increasing the concentration of a solution will increase the number of reactant particles in a given volume, allowing more frequent and successful collisions per second.

How does increasing temperature increase the rate of reaction? (Extended Tier Only)

Increasing temperature increases the kinetic energy of the particles, leading to more frequent and successful collisions with energy greater than the activation energy.

How does increasing surface area affect the rate of reaction? (Extended Tier Only)

Increasing the surface area of a solid reactant increases the rate of reaction because more surface area is exposed to the other reactant, producing a higher number of collisions per second.

True or False? For every 10 degree increase in temperature, the rate of reaction approximately doubles. (Extended Tier Only)

True. As a rule of thumb for every 10 degree increase in temperature, the rate of reaction approximately doubles

State the relationship between the number of collisions and the number of particles? (Extended Tier Only)

The number of collisions is proportional to the number of particles present.

A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the reaction.

True or False? Catalysts are consumed during the reaction.

False. Catalysts are not consumed during the reaction.

How is the rate of reaction measured?

The rate of a reaction can be measured by: Measuring how quickly the reactants are used up. Measuring how quickly the products are formed.

Give three techniques used in a lab that are used to measure the rate of a reaction.

Three techniques used in a lab that are used to measure the rate of a reaction include: measuring mass loss on a balance. measuring the volume of a gas produced. measuring a reaction where there is a colour change at the end of the reaction.

Give a disadvantage of measuring the rate of a reaction by collecting gas in an inverted measuring cylinder. (Extended tier only)

Disadvantages of measuring the rate of a reaction by collecting gas in an inverted measuring cylinder include: The delivery tube can pop out. It can be hard to read the scale upside down. Gas is lost when the bung is connected to the reaction flask.

Give a disadvantage of measuring the rate of a reaction by collecting gas using a gas syringe. (Extended tier only)

Disadvantages of measuring the rate of a reaction by collecting gas using a gas syringe include: They are fragile and expensive. They collect limited volumes. Gas can be lost while the bung is connected to the flask.

Give an advantage of measuring the rate of a reaction via the formation of a precipitate. (Extended tier only)

An advantage of measuring the rate of a reaction via the formation of a precipitate is that no specialist equipment is needed.

True or False? The gradient of the line in a rates graph is equal to the initial rate of reaction.

True. The gradient of the line in a rates graph is equal to the initial rate of reaction.

True or False? The steeper the gradient of the line in a rates graph then the slower the rate of reaction.

False. The steeper the gradient of the line in a rates graph then the faster the rate of reaction.

IGCSEChemistryCambridge (CIE)Flashcards6. Chemical ReactionsChemical Change & Rate of Reaction

Chemical Change & Rate of Reaction (Cambridge (CIE) IGCSE Chemistry)

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What is a physical change?
A physical change is a change that does not produce any new chemical substances and is often easy to reverse.
What is a chemical change?
A chemical change is a change where new chemical substances are formed, often with very different properties from the reactants.
True or False?
Physical changes are difficult to reverse.
False.
Physical changes are often easy to reverse.
What indicates a chemical change has occurred?
Signs of a chemical change include colour changes, temperature changes, and effervescence (fizzing).
What is effervescence?
Effervescence is the rapid escape of gas from a liquid in which it is dissolved, causing fizzing.
What colour change occurs in the metal displacement reaction of silver nitrate and copper?
The solid changes from orange-brown to silver, and the solution changes from colourless to blue.
State one example of a physical change.
One example of a physical change could be:
- Melting (solid to liquid)
- Making a mixture from 2 or more substances
- Dissolving a solute in a solvent
True or False?
A change in pH is an indication of a physical change.
False.
A change in pH is an indication of a chemical change.
True or False?
Dissolving a solute in a solvent is a chemical change.
False.
Dissolving a solute in a solvent is a physical change.
State the two types of reactions that cause a change in temperature.
The two types of reactions that cause a change in temperature are:
- Those that give out heat / thermal energy - exothermic
- Those that take in heat / thermal energy - endothermic
Which line on the graph indicates a reaction that has taken place at a higher temperature?
The line on the graph that represents the reaction that takes place at a higher temperature is A.
Which line on the graph indicates a reaction that has taken place with a catalyst?
The line on the graph that represents the reaction that takes place with a catalyst is A.
Which lines on the graph indicate a reaction that has taken place between acid and
- powdered calcium carbonate?
- lumps of calcium carbonate?
The lines on the graph that indicate a reaction that has taken place between acid and
- powdered calcium carbonate: A
- lumps of calcium carbonate: B
What has a greater surface area, magnesium ribbon or magnesium powder?
Magnesium powder has a greater surface area.
What four factors affect the rate of a chemical reaction?
The four factors that can affect the rate of a reaction are:
- The concentration of the reactants in solution or the pressure of reacting gases
- Surface area of solid reactants
- The temperature of the reaction
- The presence of a catalyst
Which graph will have a steeper gradient? Concentrated acid and marble chips or dilute acid and marble chips?
The graph which will have the steeper gradient is concentrated acid and marble chips.
A steep gradient on a rate of reaction graph indicates ........
A steep gradient on a rate of reaction graph indicates a fast rate of reaction.
Will increasing or decreasing the temperature increase the rate of reaction?
Increasing the temperature will increase the rate of reaction.
True or False?
Adding a catalyst to a reaction will decrease the rate.
False.
Adding a catalyst to a reaction will increase the rate.
True or False?
It is of economic interest to have a higher rate of reaction as this implies a higher rate of production and hence a more efficient and sustainable process.
True.
It is of economic interest to have a higher rate of reaction as this implies a higher rate of production and hence a more efficient and sustainable process.
Define the term collision theory. (Extended Tier Only)
A theory that explains how rates of reaction depend on the frequency and energy of collisions between reactant particles.
True or False?
All collisions result in a chemical reaction. (Extended Tier Only)
False.
Not all collisions result in a chemical reaction. Unsuccessful collisions happen when the colliding species do not have enough energy to break the necessary bonds.
State the relationship between the number of collisions and the number of particles. (Extended Tier Only)
The number of collisions is proportional to the number of particles present.
Define the term successful collision. (Extended Tier Only)
A successful collision is a collision between reactant particles that leads to the formation of product molecules.
What role does orientation play in collision theory? (Extended Tier Only)
Correct orientation is required for reacting particles to collide effectively and form products.
What is an unsuccessful collision? (Extended Tier Only)
An unsuccessful collision is one in which the reactant particles just bounce off each other and remain unchanged.
Define activation energy. (Extended Tier Only)
Activation energy is the minimum energy that reacting particles must have for a reaction to occur.
How does the increasing the kinetic energy of the particles affect the number of successful collisions? (Extended Tier Only)
Greater kinetic energy means a greater proportion of collisions will have an energy that exceeds the activation energy. There are more frequent collisions as the particles are moving quicker. Therefore, more collisions will be successful.
What factors affect the rate of reaction? (Extended Tier Only)
Factors affecting the rate of reaction include temperature, concentration, surface area, and the presence of a catalyst.
Define the term activation energy. (Extended Tier Only)
The minimum energy required for reactant particles to undergo a chemical reaction.
True or False?
Increasing concentration increases the number of collisions per second. (Extended Tier Only)
True.
Increasing the concentration of a solution will increase the number of reactant particles in a given volume, allowing more frequent and successful collisions per second.
How does increasing temperature increase the rate of reaction? (Extended Tier Only)
Increasing temperature increases the kinetic energy of the particles, leading to more frequent and successful collisions with energy greater than the activation energy.
How does increasing surface area affect the rate of reaction? (Extended Tier Only)
Increasing the surface area of a solid reactant increases the rate of reaction because more surface area is exposed to the other reactant, producing a higher number of collisions per second.
True or False?
For every 10 degree increase in temperature, the rate of reaction approximately doubles. (Extended Tier Only)
True.
As a rule of thumb for every 10 degree increase in temperature, the rate of reaction approximately doubles
State the relationship between the number of collisions and the number of particles? (Extended Tier Only)
The number of collisions is proportional to the number of particles present.
What is a catalyst?
A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the reaction.
True or False?
Catalysts are consumed during the reaction.
False.
Catalysts are not consumed during the reaction.
How is the rate of reaction measured?
The rate of a reaction can be measured by:
- Measuring how quickly the reactants are used up.
- Measuring how quickly the products are formed.
Give three techniques used in a lab that are used to measure the rate of a reaction.
Three techniques used in a lab that are used to measure the rate of a reaction include:
- measuring mass loss on a balance.
- measuring the volume of a gas produced.
- measuring a reaction where there is a colour change at the end of the reaction.
Give a disadvantage of measuring the rate of a reaction by collecting gas in an inverted measuring cylinder. (Extended tier only)
Disadvantages of measuring the rate of a reaction by collecting gas in an inverted measuring cylinder include:
- The delivery tube can pop out.
- It can be hard to read the scale upside down.
- Gas is lost when the bung is connected to the reaction flask.
Give a disadvantage of measuring the rate of a reaction by collecting gas using a gas syringe. (Extended tier only)
Disadvantages of measuring the rate of a reaction by collecting gas using a gas syringe include:
- They are fragile and expensive.
- They collect limited volumes.
- Gas can be lost while the bung is connected to the flask.
Give an advantage of measuring the rate of a reaction via the formation of a precipitate. (Extended tier only)
An advantage of measuring the rate of a reaction via the formation of a precipitate is that no specialist equipment is needed.
Which line shows magnesium powder reacting with acid and which line shows magnesium ribbon reacting with acid?
Line A shows magnesium powder reacting with acid and line B shows magnesium ribbon reacting with acid.
How long does the reaction take to complete?
The reactions takes 30 seconds to complete. The point at which the line plateaus is when the reaction is complete.
Which line shows magnesium ribbon reacting with concentrated acid and which line shows magnesium ribbon reacting with dilute acid?
Line A is magnesium reacting with concentrated acid, and line B is magnesium reacting with dilute acid.
At which point is the reaction the fastest?
The reaction is the fastest at the beginning of a reaction. Between 0 and 10 seconds.
True or False?
The gradient of the line in a rates graph is equal to the initial rate of reaction.
True.
The gradient of the line in a rates graph is equal to the initial rate of reaction.
True or False?
The steeper the gradient of the line in a rates graph then the slower the rate of reaction.
False.
The steeper the gradient of the line in a rates graph then the faster the rate of reaction.
State the equation in terms of gradient.
The equation to calculate the gradient is:
Gradient = $\frac{∆ y}{∆ x}$