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CHEMISTRY ADDITIONAL > 2b > Flashcards

2b Flashcards

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1
Q

What four things does the rate of reaction depend on?

A

Temperature, Concentration (or pressure for gases), Catalyst, Surface area of solids (size of solid pieces)

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2
Q

What formula can be used to calculate the rate of reaction?

A

Rate of reaction= Amount of reactant used or amount of product formed/ Time

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3
Q

What are the three ways that rate of reaction can be measured?

A

Precipitation, Change in mass, Volume of gas given off

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4
Q

How does precipitation help to measure the rate of reaction?

A

If the product of the reaction is a precipitate which clouds the solution, you can observe a mark through the solution and measure ow long it takes for it to disappear

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5
Q

How does change in mass help to measure the rate of reaction?

A

As the gas is released the mass disappearing is easily measured on a mass balance

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6
Q

How does volume of gas given off help to measure the rate of reaction?

A

Use gas syringe to measure volume, more gas given off during a given time interval, the faster the reaction

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7
Q

Name two disadvantages of using precipitation help to measure the rate of reaction

A

Only works where the initial solution is see-through, very subjective

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8
Q

Name two advantages and one disadvantage of using change in mass help to measure the rate of reaction

A

Very easy to plot rate of reaction graphs using the results of this method, most accurate method, however does release the gas straight into the room

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9
Q

Name one advantage and one disadvantage of using volume of gas given off to help to measure the rate of reaction

A

Quite accurate, however if the reaction is too vigorous easily blow plunger out of the end of the syringe

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10
Q

What three things increase collisions?

A

Higher temperature, higher concentration, larger surface area increases collisions

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11
Q

Why does increasing the temperature increase collisions?

A

When the temperature is increased the particles all move quicker. If they are moving quicker they will collide more often

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12
Q

How does increasing concentration (or pressure) increase collision?

A

If the solution is more concentrated it means that there are more particles of reactant which makes collisions between the right particles more likely. In a gas, increasing the pressure means the particles are more squashed up, more frequent collisions

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13
Q

How does increasing the surface are increase collision?

A

The solution will have more surface area to work on so there will be more frequent collisions

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14
Q

What is the activation energy?

A

The minimum amount of energy needed by the particles to react

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15
Q

What is a catalyst?

A

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

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16
Q

Name three advantages of catalysts

A

Saves money because doesn’t need to operate as long to produce the same amount of stuff, allows reaction to happen at lower temperature which reduces energy used up in reaction, can be used over and over again

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17
Q

Name four disadvantages of catalysts

A

Expensive to buy, need cleaning, different reactions need different catalysts, can be poisoned by impurities

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18
Q

What is an exothermic reaction?

A

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

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19
Q

Give an example of an exothermic reaction

A

Combustion

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20
Q

What is an endothermic reaction?

A

One which takes energy to the surroundings, usually in the form of heat and usually shown by a fall in temperature

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21
Q

Are reversible reactions exothermic or endothermic?

A

Both

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22
Q

In reversible reactions if the reaction is endothermic in one direction, what will it be in the other direction?

A

Exothermic

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23
Q

What pH is the strongest acid and the strongest alkali?

A

The strongest acid has pH 0. The strongest alkali has pH 14

24
Q

What pH is pure water?

A

pH 7

25
Q

What kind of ions do acids form in water?

A

H+ ions

26
Q

What is an alkali?

A

A base that dissolves in water

27
Q

What kind of ions do alkalis form in water?

A

OH- ions

28
Q

What happens in the reaction between acid and base?

A

Neutralisation. Acid + base = salt + water

29
Q

What happens in the reaction between acid and a metal?

A

Acid + metal = salt + hydrogen

30
Q

What happens in the reaction between acid and a metal oxide?

A

Acid + metal oxide = salt + water

31
Q

What happens in the reaction between acid and a metal hydroxide?

A

Acid + metal hydroxide = salt + water

32
Q

What can ammonia be reacted with to create a neutral salt that is a good fertiliser?

A

Nitric acid to make ammonium nitrate

33
Q

Do you add the metal, metal oxide or hydroxide to the acid or the other way around?

A

You add the metal, metal oxide or hydroxide to the acid

34
Q

How do you make a soluble salt using a metal or an insoluble base?

A

Add metal, metal oxide or hydroxide to the acid, filter out excess metal to get salt solution. To get pure, solid crystals of salt, evaporate some of the water and then leave the test to evaporate very slowly. This is called crystallisation

35
Q

How do you make soluble salts using an alkali?

A

Have to add exactly the right amount of alkali to just neutralise the acid- need to use an indicator to show when the reaction is finished, repeat using exact same amounts but without indicator so that the salt isn’t contaminated with indicator, evaporate off the water

36
Q

If you want to make an insoluble salt, what kind of reaction do you need to use?

A

Precipitation

37
Q

How do you make insoluble salts using an precipitation reaction?

A

Mix the two solutions containing the ions that you need, one the salt has precipitated out (and is lying at the bottom of the flask) all you have o do is flatware it from the solution and dry it

38
Q

Name two uses for precipitation reactions

A

Remove poisonous ions from drinking water, making water softer so that it layers properly by removing calcium and magnesium

39
Q

What does electrolysis mean?

A

Splitting up with electricity

40
Q

How does electrolysis work?

A

By passing an electric current through an ionic substance thats molten or in solution, it breaks down into the elements that its made of

41
Q

What is an electrolyte and why does it work?

A

It is the liquid required in electrolysis to conduct the electricity, it contains free ions, they’re usually molten or a dissolved ionic substance

42
Q

What is the flow of electrons in electrolysis?

A

Electrons are taken away from ions at the positive electrode and given to other ions at the negative electrode

43
Q

Electrolysis always involves an oxidation and a reduction. OIL RIG?

A

Oxidation Is Loss, Reduction Is Gain

44
Q

In the electrolysis of molten lead bromide, what is produced at at the negative and positive electrode?

A

Lead is produced at the -ve and bromine is produced at the +ve

45
Q

Sometimes there are more than two free ions in the electrolyte, if salt is dissolved in water there will also be some what?

A

H+ and OH- ions

46
Q

What will happen at the negative electrode in electrolysis, if metal ions and H+ ions are present and why?

A

The metal ions will stay in solution if the metal is more reactive than Hydrogen. This is because the more reactive an element is, the keener it is to stay as ions

47
Q

What will happen at the positive electrode in electrolysis, if OH- and halide ions are present?

A

Molecules of chlorine, iodine or bromine will be formed. If no halide is present then oxygen will be formed

48
Q

In the electrolysis of Sodium Chloride solution, what is produced at each electrode?

A

Hydrogen at -ve because sodium is more reactive, Chlorine at +ve, NaOH left in the solution

49
Q

What do half-equations show?

A

The reactions at each electrode in electrolysis

50
Q

Name two useful products formed from the electrolysis of Sodium Chloride solution

A

Chlorine can be used in the production of bleach and plastics, Sodium hydroxide is a very strong alkali and is used in the production of e.g soap

51
Q

What can be used to remove aluminium form its ore?

A

Electrolysis

52
Q

What can be used to dissolve aluminium oxide in before electrolysis and why?

A

Molten cyrolite, brings the temperature down to about 900ºc cheaper and easier.

53
Q

In the electrolysis of Aluminium oxide, what are the electrodes made of and what forms at each electrode

A

Electrodes are made of carbon (graphite), aluminium forms at the negative electrode and oxygen forms at the positive

54
Q

What is one disadvantage of using carbon as electrodes?

A

The oxygen reacts with the carbon to produce carbon dioxide which is bad for the environment and also means that the positive electrode will be ‘eaten away’ gradually so will have to be replaced

55
Q

What is electroplating?

A

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

56
Q

In electroplating, which electrode needs what?

A

The negative electrode needs the metal object you want to plate and the positive electrode is the pure metal you want it to be plated with. Will also need the electrolyte to contain ions of the plating metal

57
Q

Give two different uses of electroplating

A

Give two different uses of electroplating

Decoration- make it look pretty, Conduction- make something conduct electricity

CHEMISTRY ADDITIONAL (2 decks)

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