rates of reactions + atoms

Question 1

Define variables

Answer 1

Something that can be changed in a chemical reaction

Question 2

Examples of variables?

Answer 2

Temprano
Particle size
Concentration
Volume
Mass

Question 3

What is a fair test?

Answer 3

In order to determine what factor is affecting a chemical reaction you must only change one variable at a time.

Question 4

How do you carry out a fair test?

Answer 4

If you only change one variable at a time then you are carrying out a fair test

Question 5

What do large particles result in

Answer 5

A slow reaction

Question 6

What do small particles result in

Answer 6

a fast reaction

Question 7

What does low concentration result in

Answer 7

a slow reaction

Question 8

What does high concentration result in

Answer 8

a fast reaction

Question 9

What does low temperature result in

Answer 9

A slow reaction

Question 10

What does high temperature result in

Answer 10

A fast reaction

Question 11

What is the effect of particle size on a reaction

Answer 11

As particle size decreases - surface area increases - area available for collision increases.

Question 12

What is the effect of concentration on a reaction

Answer 12

Increasing the concentration of reactants- increases the number of collisions

Question 13

What is the effect of temperature on a reaction

Answer 13

As the temperature increases-amount of energy a particle has increases-the faster a particle moves around-more likely particles are to collide-rate of reaction increases

Question 14

What is the effect of a catalyst on a reaction

Answer 14

A substance that speeds up the rate but can be recovered chemically once reaction has given to completion

Question 15

Explain collision theory?

Answer 15

For a chemical reaction to occur the reactant particles must collide this provides the energy to break the bonds in the reactants and from new ones in the product

Question 16

Explain Successful collisions

Answer 16

Not all collisions result in chemical reactions those that do are successful in order for this to happen the must collide with the sufficient energy and correct geometry.

Question 17

What do all chemical reactions produce

Answer 17

New substances

Question 18

How can the speed of reaction be found?

Answer 18

By measuring how fast the new substance is formed

Question 19

What happens at the A part of the graph(longer sorta straighter bit )

Answer 19

Reaction is at its fastest/concentration of reactants is highest

Question 20

What happens at point B of the graph (still going higher but becoming steeper in middle of graph small)

Answer 20

Reaction is decreasing/reactants being used up

Question 21

What happens at pint C on graph(part of line is now horizontal)

Answer 21

Reaction is finished (gone to completion) all reactants have been used up+converted to products

Question 22

Reading Particle size on graph

Answer 22

If particle size is increasing the slope is less steep and plataeu has no change if it is decreasing slope is steeper and plateau also no change

Question 23

Reading concentration on Graph

Answer 23

If it is increasing the slope is steeper and plateau is higher, if it is decreasing the slope is also steeper but plateau is lower

Question 24

Reading temperature of graph

Answer 24

If it is increasing the slope is steeper and plateau no change, if it is decreasing slope is less steep but plateau also no change

Question 25

Reading the use of catalyst/enzyme on graph

Answer 25

Slope is steeper but plateau no change

Question 26

Reading an increase in mass/volume of graph

Answer 26

The slope is unchanged but plateau is higher

Question 27

What do you need to calculate average rate?

Answer 27

The initial + final quantities and the time interval

Question 28

What is the formula for finding average rate

Answer 28

🔺quantity / 🔺 t

Question 29

What is delta 🔺

Answer 29

Change in

Question 30

What units are used in average rate calculations

Answer 30

Cm s-1 or cm3/s NOT cm3/s-1

Question 31

Describe periodic table

Answer 31

Everything in the world is made up of 118 elements that scientists have classified in to the periodic table and into groups of similar chemical properties

Question 32

Describe the properties of group 1 - Alkali metals

Answer 32

Very reactive Stored under oil Soft (can be cut with a knife) React with water to form an alkaline solution React with oxygen to form metal oxides

Question 33

Describe the properties of groups 2&3 the transition metals

Answer 33

Hard and dense Less reactive than the alkali metals Used in catalysts Form coloured compounds

Question 34

Describe group 7 the halogens properties

Answer 34

Diatomic elements All toxic Florine added to toothpaste to prevent decay Chlorine added to swimming pools to sterilise Iodine used to treat wounds

Question 35

Describe the properties of group 8 the noble gases

Answer 35

Least reactive of all elements Do not react

Question 36

What are elements made up of

Answer 36

Only one type of atom

Question 37

What are atoms made up of?

Answer 37

3 different elementary particles; protons electrons and neutrons

Question 38

Describe the nucleus

Answer 38

The centre of the atom contains the protons and neutrons +charge

Question 39

Describe protons

Answer 39

+charged found in the nucleus RAM=1

Question 40

Describe electrons

Answer 40

-charged found orbiting the nucleus RAM=almost zero

Question 41

Describe neutrons

Answer 41

neutral charge located in the nucleus RAM = 1

Question 42

Explain why atoms are neutral

Answer 42

Because the number of positively charged protons are equal to the neagativley charged electrons Also note that the neagative electrons orbit around the positive protons, opposites attract

Question 43

What do elements have associated with them?

Answer 43

A symbol and 2 numbers

Question 44

what is the mass number and where is it written

Answer 44

The number of protons and neutrons, it is to the left of the symbol on the top

Question 45

what is the atomic number and and where is it written?

Answer 45

The number of protons/electrons it is erigen on the left of the symbol on the bottom

Question 46

How is the number of of neutrons calculated?

Answer 46

Mass no. - atomic no.

Question 47

Define isotopes

Answer 47

Atoms that are of the same element and have the same atomic number but different mass number

Question 48

What do isotopes have?

Answer 48

The same chemical properties i.e. all the isotopes of of hydrogen have the same chemical behaviour