chemical changes and structure and rates of reaction Flashcards

1
Q

Explain the collision theory.

A

For a reaction to occur the reactant particles must come into contact, or collide with each other. The more collisions that occur, in a given time, the faster the reaction.

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2
Q

When there is low temperature, what is the rate of reaction like ?

A

The particles are moving slowly, resulting in very few collisions in a given time. The reactions is slow.

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3
Q

When there is a high temperature, what is the rate of reaction like?

A

The particles are moving quickly, resulting in many collisions in given time.The reaction is fast.

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4
Q

why do substances move about faster when they are heated?

A

They have more kinetic energy.

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5
Q

What is the concentration of a solution?

A

The measure of the number of particles of a solute in a given volume of solvent.

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6
Q

What does the word “mole” mean?

A

The measure of the number of particles of a substance there are.

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7
Q

When there is a dilute solution (low concentration) , what is the rate of reaction like?

A

There are a small number of moles of solute in a certain volume of solvent.This results in very few collisions and the reaction is slow.

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8
Q

When there is a concentrated solution (high concentration) , what is the rate of reaction like?

A

There are a greater number of moles of solute in the same volume of solvent. This results in more collisions and the reaction is fast.

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9
Q

Why does particle size/surface area have an effect on the rate of reaction?

A

when a solid reacts, it is only the particles on the surface area of the solid which come into contact with the other reactant.

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10
Q

what is the rate of reaction like when there is a large particle size?

A

The large particle size has a small surface area and limited contact with the other reactant. Therefore few collisions take place between the two reactants and the reaction is slow.

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11
Q

What is the rate of reaction like when there is a small particle size?

A

The small particle area has a large surface area and much greater contact with the other reactant.Therefore many collisions take place between the two reactants and the reaction is fast

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12
Q

What are the two ways you can monitor the rate of a chemical reaction?

A

By the change of mass and the change of volume of gas.

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13
Q

When is the concentration of reactants the highest?

A

At the start.

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14
Q

Why does the concentration of reactants decrease with time?

A

The reactants are being used up.

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15
Q

What does the gradient of the curve mean?

A

The slope of the curve.

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16
Q

What gas escapes through the cotton wool in the mouth of the conical flask?

A

Carbon dioxide.

17
Q

What system is used for the method of gas collection?

A

Gas syringe.

18
Q

What is the units for measuring concentration change?

A

mol l-1

19
Q

What is the units for measuring gas volume change?

A

cm3

20
Q

What is the units for measuring mass change?

A

g

21
Q

What is the unit for measuring seconds?

A

S-1

22
Q

What is the unit for measuring minutes?

A

min-1

23
Q

What is the unit for measuring hours?

A

hr -1

24
Q

Name four factors that increase the rate of reaction.

A

Increasing the concentration of reactant(s).
Increasing the temperature of the reactant(s).
Decreasing the particle size of the reactant(s)- only affects reactions involving a solid reactant.
The use of a catalyst.

25
Q

How can the average rate of reaction be calculated?

A

the average rate of reaction=
change in quantity of chemical divided by time interval for change.
(can be found in data booklet)