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Chemistry 1 > C3 > Flashcards

C3 Flashcards

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1
Q

What is an exothermic reaction?

A

A reaction which gives out energy to the surroundings in the form of heat

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2
Q

What is an endothermic reaction?

A

A reaction which takes in energy from the surroundings making the temperature fall

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3
Q

How can you test whether it’s an endo or exothermic reaction?

A

Taking the temperature of the reactants
Mixing them in a polystyrene cup
Measuring the temperature of the solution at the end

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4
Q

Why is bond breaking an endothermic reaction?

A

Energy must be supplied to break the bonds which is taken from the surroundings causing a fall in temperature

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5
Q

Why is bond formation an exothermic reaction?

A

Energy is released when new bonds are formed

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6
Q

What happens during a chemical reaction?

A

Old bonds are broken and new ones are formed

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7
Q

What makes a reaction exothermic?

A

The energy released in bond formation is greater than the energy used in breaking the old bonds

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8
Q

What makes a reaction endothermic?

A

The energy required to break the old bonds is greater than the energy released when new bonds are formed

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9
Q

What is a calorimetric experiment?

A

Heat water by burning a fuel to measure energy transfer

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10
Q

Describe the calorimetric method

A 
Reduce draughts by using a screen
Put fuel in a spirit burner and weigh it
Measure water into a copper calorimeter 
Take initial water temp then set fire to the burner
When heat from burner has made water temp rise by 20-30 degrees stop
and record highest temp reached
Re weigh burner and fuel
Work out energy output per gram
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11
Q

What is the specific heat capacity of water?

A

4.2J/g/degreesC

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12
Q

How do you work out the amount of energy transferred per gram of fuel?

A 
Work out energy transferred:
Energy transferred (j) =
Mass of water (g) X specific heat capacity of water X temp change (degrees C)
Then energy per gram:
Energy per gram (J/g) =
Energy released (j) /transferred
-------------------------------------
Mass of fuel burned (g)
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13
Q

How do you make it a fair test?

A

Keep the conditions the same

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14
Q

Give an example of some slow reactions

A

Rusting of iron

Chemical weathering

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15
Q

Give an example of a moderate speed reaction

A

Metal reacting with dilute acid to produce a gentle stream of bubbles

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16
Q

Give 2 examples of fast reactions

A

Burning

Explosions

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17
Q

How can you observe the rate of reaction?

A

Measuring how quickly a gas is produced

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18
Q

What are two ways of measuring how quickly a gas is produced?

A

Measuring the change in mass (mass will fall as gas released, measure at regular time intervals)
Measure the volume of gas given off (use a gas syringe and measure at regular time intervals)

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19
Q

What does the rate of a chemical reaction depend on?

A

The collision frequency of the reacting particles (more collisions = faster reaction)
Energy transferred during a collision (need enough energy to be successful)

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20
Q

What does the amount of product you get from a reaction depend on?

A

The amount of reactant you start with

Amount of product is directly proportional to the amount of limiting reactant

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21
Q

Name four things you can do to increase the amount of collisions in a reaction

A

Increase the temperature
Increase concentration (or pressure if it’s a gas)
Increase the surface area
Use a catalyst

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22
Q

Why does increasing the temperature make there more collisions?

A

Gives the particles more energy so they move quicker

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23
Q

Why does increasing the surface area increase the amount of collisions?

A

More area for the collisions to happen on so collisions increase

24
Q

What is a catalyst?

A

A substance which increases the speed of a reaction without being chemically changed or used up in the reaction

25
Q

How does a catalyst work?

A

Gives the particles a surface to stick to (attracts them) where they can bump into each other and reduces the energy needed for a successful collision

26
Q

In the periodic table which number is the relative atomic mass?

A

The top one/bigger one

27
Q

What’s relative formula mass?

A

All the relative atomic masses of a compound added together

28
Q

Why do we say that mass is conserved in a chemical reaction?

A

Because no atoms are destroyed and none are created so there is the same number and types of atoms on each side of a reaction

29
Q

What are the three steps for working out masses in reactions?

A

Wrote out the balanced equation
Work out the RFM’s
Divide to get one gram then Multiply to get what the questions asking you

30
Q

What does the atom economy of a reaction tell you?

A

How much of the mass of the reactants is wasted in a reaction

31
Q

What is the equation for atom economy?

A

Total RFM of desired products
———————————— X 100
Total RFM of all products

32
Q

Why is high atom economy better for profits and environment ?

A

Low economy uses up resources quickly and make materials that need to be disposed of
Resources are expensive and disposal is also expensive

33
Q

What is percentage yield?

A

Compared actual with predicted yield tells you how successful the experiment was

34
Q

What is the equation for percentage yield?

A 
Actual yield (grams)
--------------------------- X100
Predicted yield (grams)
35
Q

Why do industrial processes want as high a percentage yield as possible?

A

To reduce waste and costs

36
Q

What are the 4 things which can reduce yield?

A

Evaporation
Not all reactants react (reversible reactants)
Filtration
Transferring liquids

37
Q

What is batch production?

A

Only operates at certain times e.g pharmaceutical drugs

38
Q

Why is batch production sometimes the most cost effective method?

A

Flexible - several different products can be made using the same equipment
Start up costs are low as its small scale

39
Q

What are the disadvantages to batch production?

A

Labour intensive

Hard to keep same quality from batch to batch

40
Q

What is continuous production?

A

Runs all the time e.g large scale industrial manufacture

41
Q

What are the advantages of continuous production?

A

Production never stops so no time wasted
Automatic
Quality is consistent

42
Q

What are the disadvantages of continuous production?

A

Start up costs are huge and it isn’t cost effective to run at less than full capacity

43
Q

Why do pharmaceutical drugs often cost a lot?

A

Research and development - finding a suitable compound, testing and modifying
Trialling
Manufacture - multi step batch production is labour intensive
Raw materials are often rare and need to be extracted from plants (expensive)

44
Q

How do you extract a substance from a plant?

A

Crush the plant
Boil to dissolve in a suitable solvent
Seperate by chromatography
Extract (cut out) which one you want

45
Q

How can you test for purity by chromatography?

A

Pure substances won’t be separated out

46
Q

How can you test for purity using melting and boiling points?

A

Pure substances have specific melting and boiling points

47
Q

Name two allotropes of carbon?

A

Diamond

Graphite

48
Q

What is an allotrope?

A

Different structural forms of the same element in the same physical state

49
Q

Describe diamond

A

Sparkly (lustrous) and colourless
Each atom forms four covalent bids in a very rigid structure making them really hard
Strong covalent bonds take a lot of energy to break = very high melting point
Doesn’t conduct electricity (no free electrons or ions)

50
Q

What is diamond ideal for?

A

Jewellery and cutting tools

51
Q

Describe graphite

A

Black and opaque yet still shiny
Each atom only forms three covalent bonds creation sheets which are free to slide over each other
Layers are weakly held together so are slippery and rub off
High melting point
Lost of delocalised electrons that move so it conducts electricity

52
Q

Why does Carbon form giant molecular structures?

A

Because it can form lots of covalent bonds with itself

53
Q

Describe giant molecular structures

A

Strong and have high melting pints
Lots of covalent bonds
Don’t dissolve in water
Usually don’t conduct electricity (graphite is an exception)

54
Q

What are fullerenes?

A

Nano particles

Molecules of carbon which are shaped like closed tubes or hollow balls

55
Q

What can fullerenes be used for?

A

Cage other molecules - new way of delivering drugs into the body
Join together to form nanotubes
Nanotubes have huge surface area so can help make industrial catalysts by having individual catalyst molecules attach to it

56
Q

What kind of reaction is combustion?

A

An exothermic reaction

Chemistry 1 (4 decks)

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