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Flashcards in Chemistry 6 Deck (65)
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0

What four things affect rate of reaction ?

Temperature
Concentration
Catalyst
Surface area of solids

1

In what state does pressure affect rate of reaction ?

Gases

2

How can you find the rate of reaction ?

Amount of reactant used or amount of product formed divided by time

3

Give three ways rate of reaction can be measured ?

Precipitation
Change in mass
Volume of gas given off

4

How do you measure rate of reaction with precipitation ?

Place a cross, or mark, below the solution and time how long it takes before the mark is no longer visible

5

What do you look for when measuring a change in mass ? How do you find this ?

You are looking for a change in the mass, the quicker the change the faster the rate of reaction. To find this you place the solution on weighing scales and let the reaction take place

6

What piece of equipment measures the volume of gas given off ?

A gas syringe

7

How is the volume of gas given off in a reaction measured ?

A gas syringe measures the gas given off by collecting it as it leaves the beaker. The more gas given off the faster the rate of reaction

8

What is an example of an experiment that measures volume given off ?

The reaction of hydrochloride acid and marble chips

9

Name a reaction that is good for measuring a change in mass

Magnesium metal with dilute hydrochloric acid

10

What does the decomposition of hydrogen peroxide show ?

The effects of different catalysts on rate of reaction

11

What catalyst speeds up the decomposition of hydrogen ?

Manganese (IV) oxide catalyst

12

What is collision theory ?

More collisions between particles increases the rate of reaction.

13

How does temperature increase rate of reaction in regards to collisions ?

When the temperature increase the particles gain energy and move quicker. If they move quicker they will collide more often

14

How does higher concentration increase collisions ?

If there is a higher concentration there are more particles in the same amount of space. Therefore they are more likely to collide as the space becomes confined

15

Why does a smaller surface area increase the rate of reaction ?

The particles, when smaller, have a larger area to work on so they can collide with more things and more frequently

16

What is a catalyst ?

A catalyst is a substance which speeds up a reaction, without being changed or used up in the reaction

17

How does using a catalyst reduce cost in industrial reactions ?

• By increasing rate of reaction the plant doesn't need to operate for so long because it happens quicker
• Works at a lower temperature, reducing energy costs

18

What are the disadvantages of using catalysts ?

• They are expensive
• they can be 'poisoned' by impurities and stop working

19

What is an exothermic reaction ?

A reaction which transfers energy to the surroundings, usually in the form of heat and shown by a rise in temperature

20

What is the best example of an exothermic reaction ?

Combustion - it gives out a lot of heat through burning

21

What is an endothermic reaction ?

A reaction which takes i energy from the surroundings, usually in the form of heat and shown by a fall in temperature

22

What is a good example of an endothermic reaction ?

Thermal decomposition

23

If a reversible reaction is endothermic one way, what will it be the other way ?

Exothermic, the energy absorbed one way is equal to the energy released the other

24

What number is neutral on the pH scale ?

7

25

What numbers are acids on the pH scale ?

0-6

26

What numbers are alkalis on the pH scale ?

8-14

27

What is an indicator ?

A dye that changes colour depending on whether it's above or below a certain pH

28

What are substance with a pH of greater than 7 also known as ?

A Base

29

In what way is an alkali different to a base ?

An alkali is a base that dissolves in water