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Science 2 > Chemistry 6 > Flashcards

Chemistry 6 Flashcards

0
Q

In what state does pressure affect rate of reaction ?

A

Gases

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1
Q

What four things affect rate of reaction ?

A

Temperature
Concentration
Catalyst
Surface area of solids

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2
Q

How can you find the rate of reaction ?

A

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

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3
Q

Give three ways rate of reaction can be measured ?

A

Precipitation
Change in mass
Volume of gas given off

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4
Q

How do you measure rate of reaction with precipitation ?

A

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

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5
Q

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

A

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

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6
Q

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

A

A gas syringe

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7
Q

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

A

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

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8
Q

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

A

The reaction of hydrochloride acid and marble chips

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9
Q

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

A

Magnesium metal with dilute hydrochloric acid

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10
Q

What does the decomposition of hydrogen peroxide show ?

A

The effects of different catalysts on rate of reaction

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11
Q

What catalyst speeds up the decomposition of hydrogen ?

A

Manganese (IV) oxide catalyst

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12
Q

What is collision theory ?

A

More collisions between particles increases the rate of reaction.

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13
Q

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

A

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

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14
Q

How does higher concentration increase collisions ?

A

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

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15
Q

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

A

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

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16
Q

What is a catalyst ?

A

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

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17
Q

How does using a catalyst reduce cost in industrial reactions ?

A
  • 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
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18
Q

What are the disadvantages of using catalysts ?

A
  • They are expensive

* they can be ‘poisoned’ by impurities and stop working

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19
Q

What is an exothermic reaction ?

A

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

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20
Q

What is the best example of an exothermic reaction ?

A

Combustion - it gives out a lot of heat through burning

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21
Q

What is an endothermic reaction ?

A

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

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22
Q

What is a good example of an endothermic reaction ?

A

Thermal decomposition

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23
Q

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

A

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

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24
Q

What number is neutral on the pH scale ?

A

7

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25
Q

What numbers are acids on the pH scale ?

A

0-6

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26
Q

What numbers are alkalis on the pH scale ?

A

8-14

27
Q

What is an indicator ?

A

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

28
Q

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

A

A Base

29
Q

In what way is an alkali different to a base ?

A

An alkali is a base that dissolves in water

30
Q

Acid + base —> ?

A

Salt + water, this is called neutralisation

31
Q

What does aq stand for and what does it mean ?

A

Aqueous- dissolved in water

32
Q

Metals + acid —-> ?

A

Salts + hydrogen

33
Q

What happens when sodium is reacted with acid ? And why ?

A

They react explosively because sodium is a very reactive metal

34
Q

Why does copper not react at all with dilute acids ?

A

It is less reactive than hydrogen

35
Q

What type of salt does hydrochloric acid produce ?

A

Chloride salts

36
Q

Sulphate salts come from what acid ?

A

Sulphuric acid

37
Q

What do metals less reactive than hydrogen not do ?

A

React with acid

38
Q

What are metal oxides and metal hydroxides ? And why ?

A

Bases - because they have a pH of over 7. Some dissolve in water - these are alkalis

39
Q

How can ammonia be converted into fertiliser ?

A

Neutralisation - ammonia dissolves in water to form an alkaline solution. This is reacted with nitric acid to form a salt (ammonium nitrate) - the fertiliser

40
Q

Why type of salts do chlorides, sulfates and nitrates mostly make ?

A

Soluble salts (in water)

41
Q

Insoluble salts in water are made by what ?

A

Most oxides an hydroxides, some break the rule

42
Q

What does electrolysis mean ?

A

Splitting up with electricity

43
Q

How does electrolysis work ?

A

An electric current is passed through an ionic substance that’s molten or in solution, it breaks down into the elements it’s made of

44
Q

What is the electrolyte ?

A

A liquid that conducts the electricity for electrolysis

45
Q

Oxidation is …

A

Loss

46
Q

Reduction is …

A

Gain

47
Q

Do oxidation and reduction have to involve oxygen ?

A

No, it is used in electrolysis with the loss or gain of electrons

48
Q

True or false - only oxidation is involved in electrolysis

A

False - electrolysis always invokes oxidation and reduction because one electrode loses electrons and the other gains electrons

49
Q

Lead bromide is a salt, what does it have to be to conduct electricity ?

A

Molten

50
Q

Describe the electrolysis of lead bromide

A

The molten lead bromide acts as the electrolyte, lead is produced at the +ve electrode and bromide at the -ve

51
Q

What happens at the negative electrode if the metal ions and H+ ions are present ?

A

If the metal is more reactive than hydrogen it will stay in solution because more reactive elements want to stay as ions. So hydrogen is produced

52
Q

What happens at the positive electrode if OH- and halides (Cl-, Br-, I-) are present ?

A

Molecules of either chlorine, Bromine or Iodine will be formed. I no halides are present then oxygen will be formed

53
Q

What is common salt ?

A

Sodium chloride

54
Q

What three things are produced when common salt is electrolysed ?

A

Hydrogen
Chlorine
Sodium Hydroxide

55
Q

What is produced at the negative electrode when sodium chloride is electrolysed ?

A

Hydrogen

56
Q

What is found at the positive electrode when common salt is electrolysed ?

A

Chlorine

57
Q

Where is sodium hydroxide found once electrolysis of common salt is complete ?

A

Left in the solution

58
Q

What is bauxite ?

A

The main ore of aluminium, aluminium oxide

59
Q

How is cryolite used in the purification of aluminium in bauxite ?

A

Bauxite is dissolved in molten cryolite. Bauxite has a very high melting point, so it would be very expensive to electrolyte, cryolite is lower which reduces the costs

60
Q

What is electroplating ?

A

Using electrolysis to coat the surface of one metal with another metal

61
Q

What is at the negative electrode when electroplating ?

A

The metal object you wish to plate

62
Q

What is at the positive electrode when electroplating ?

A

The pure metal you want the object to be plated with

63
Q

What does the electrolyte need to contain in electroplating ?

A

It needs to contain the ions of the plating metal

64
Q

How can electroplating be used ?

A

Decoration - to cover cheaper metals in more expensive metals
Conduction - copper can coat electronic circuits to conduct electricity

Science 2 (7 decks)

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