C2B Flashcards

1
Q

Examples of slow, moderate and fast?

A
  • Slow - rusting of iron
  • moderate - metal reacting with an acid
  • fast - reactions in an explosion
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2
Q

What affects rate of reaction?

A

1, Temp
2, concentration
3. catalyst
4. surface area

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3
Q

What would typical rate of reaction graphs look like?

A
  • slow reaction = not a steep line

* faster rection = steep line that increases quickly and then levels off

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4
Q

How do you measure rate of reaction?

A

measure how quickly the reactants are used up
OR
how quickly the products are formed

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5
Q

How do you calculate the rate of reaction?

A

time

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6
Q

Different ways to measure the rate of reactions and explain them

A
  1. Precipitation - the solution clouds as the reaction is a precipitate. Mark at base of flask and time how long before it disappears
  2. Change in mass- usually gas given off. Carried out by mass balance - as gas is released mass is lost
  3. Volume of gas given off - use a gas syringe and measure amount of gas released. More gas means a faster reaction
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7
Q

Give an examples of rate of reaction experiments

A
  • Hydrochloric acid and marble chips
    Break into small or large chunks to judge the affect of surface area
  • Magnesium metal and dilute HCI
    Shows affect of concentration - more concentrated = faster reaction
  • Sodium thiosulfate and HCI - will produce a cloudy precipitate. Shows that the higher the temp, quicker the reaction
  • Decomposition of hydrogen peroxide - shows affect of catalyst
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8
Q

What is collision theory?

A

The idea that as particles gain more energy they will move/vibrate more which causes more frequent collisions which increases the rate of reaction.

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9
Q

How does collision theory apply to temp, concentration and surface area?

A

temp - higher temp means more energy which makes particles move quicker = more frequent collisions

concentration - higher concentration means more particles in area = more frequent collisions

surface area - more surface area means more particles and more exposed for solution to work on = more frequent collisions

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10
Q

Whats a catalyst?

A

substance which speeds up a reaction without being changed or used up

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11
Q

How do catalysts help in industry?

A
  • increase reactions which saves money
  • allow reactions to work at lower temperatures
  • use less energy
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12
Q

Disadvantages of catalysts

A
  • Used up over time
  • can get poisoned
  • initially expensive
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13
Q

What is exothermic?

A

A reaction which transfers energy to the surrounding areas usually in the form of heat and causes a rise in temperature

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14
Q

Example of exothermic reactions?

A

Combustion
oxidation reactions (sodium to water)
Neutralisation reactions

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15
Q

Exothermic reactions in everyday situations?

A

Hand warmers - oxidation of iron in air

Self-heating cans - chemicals in base

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16
Q

What is endothermic?

A

A reaction which takes energy from its surrounding usually in the form of heat which causes a temperature decrease

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17
Q

Examples of endothermic reactions?

A

Thermal decomposition

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18
Q

Is a reversible reaction endothermic or exothermic?

A

BOTH
Exothermic in one direction and endothermic in another direction. So the energy absorbed is the equal to the energy released.

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19
Q

What does anhydrous mean?

A

A reaction that is without water

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20
Q

What does hydrated mean?

A

A reaction with water

21
Q

What is an acid?

A

A substance with the pH of less than 7 and form H+ ions in water

22
Q

What is a base?

A

a substance with the pH of greater than 7

23
Q

What is an alkali?

A

A base that dissolves in water and form OH-ions in water

24
Q

What is the neutralisation equation?

A

acid + base —-> salt + water
or
H+ + OH- ——–> H20

25
Q

Symbols in equations?

A
s  = solid
l  = liquid
g  = gas
aq    = dissolved in water
26
Q

What happens when you react an acid with a metal?

A

acid + metal ——> salt + hydrogen

The more reactive the metal the faster the reaction

27
Q

How can you test for hydrogen in a reaction?

A

Squeaky pop test

Put a burning splint in the test tube

28
Q

What salts does hydrochloric acid, sulphuric acid and nitric acid make

A
  • Chloride - HCI
  • Sulfate - H2SO4
  • Nitrate
29
Q

What do metal oxide and acids make?

A

Acid + metal oxide ——> salt + water

30
Q

What does acid and metal hydroxide make?

A

Acid + metal —-> salt and water

31
Q

How is ammonia neutralised?

A

React with nitric acid

Ammonia + nitric acid —–> ammonium nitrate

32
Q

Why is ammonia nitrate a good fertiliser?

A

Has nitrogen from two sources, ammonia and the nitric acid - double dose. Nitrogen used to make proteins

33
Q

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

A

Pick the right acid plus a metal/insoluble base
Add the metal, metal oxide or hydroxide to the acid - solid will dissolve in acid.
Filter out excess metal when reaction finishes (solids sink), metal oxide or hydroxide to get salt solution

34
Q

How do you make soluble salts from alkalis?

A

You can’t tell when the reaction is finished so can’t just filter out what’s left.
Have to add exactly right amount of alkali to neutralise the acid. Then use an indicator - repeat using same volumes of alkali and acid so salt isn’t contaminated with indicator
Then evaporate off the water to crystallise salt

35
Q

What is precipitation reaction used for?

A

If the salt you want to make is insoluble.
Pick 2 solutions that contain the ions you need.
Precipitate the salt out and it’s all at the bottom of the flask, filter it from solution and dry it

36
Q

Precipitation reactions in real life

A

Remove poisonous ions from drinking water

Removing unwanted ions from sewage

37
Q

What is electrolysis?

A

Passing electric current through a substance to break it down into the elements it’s made of

38
Q

How does electrolysis work?

A

Requires a liquid to conduct - called the electrolyte

Free electrons in the electrolyte carry the the electricity and conduct the electricity - allows it to work

39
Q

How does electrolysis work in a electrical circuit?

A

Electrons are taken from ions at positive electrode and given to ions at the negative electrode - they become atoms/molecules and are released

40
Q

What is OIL RIG

A

Oxidation Is Loss
Reduction Is Gain

OFF ELECTRONS

41
Q

Electrolysis of molten lead bromide

A

Lead is produced at the negative electrode - Bromine produced at positive electrode
Positive ions are attracted to negative electrode - they gain electrons
Negative ions go to positive electrode so lose electrons
1 lead accepts 2 electrons to become a lead atom
2 bromine accept 1 electron be become bromine molecule

42
Q

What effects the products formed by electrolysis?

A

Reactivity
So if theres more than two free electrons metal ions will stay in solution and be more reactive than hydrogen - so element stays as ions hydrogen is produced

43
Q

What products are produced in the electrolysis of sodium chloride solution?

A
  • Hydrogen
  • Chlorine
  • Sodium hydroxide
44
Q

What happens in the electrolysis of sodium chloride solution?

A

+ ions attracted to -ve electrode (gain electrons)
-ve ions attracted to +ve electrode (lose electrons)
Hydrogen produced at negative electrode and Chlorine produced at positive electrode
*-ve electrode - 2 hydrogens accept 2 electrons be form 1 hydrogen molecule H2
*+ve electrode - 2 chlorine lose electrons to form 1 chlorine molecule

45
Q

What stays in the solution in the electrolysis of sodium chloride?

A

Sodium ions - more reactive than hydrogen
and Hydroxide ions form water so are left behind
They mix to become sodium hydroxide (left behind)

46
Q

Useful products from the electrolysis of sodium chloride?

A
  • Bleach
  • plastics
  • soap
47
Q

How is aluminium extracted from its ore?

A

Electrolysis

  • has high melting point so too expensive to melt
  • Instead its dissolved in molten crysolite which reduces them
  • ammonium forms at negative electrode and oxygen forms at positive electrode
48
Q

Whats electroplating?

how does it work

A

^ uses electrolysis to coat the surface of one metal with another
^ put what you want to plate at negative electrode and the thing you want it to be plated with at the positive electrode

49
Q

Whats electroplating used for?

A

Decoration - make things look nicer

Conduction - put good conductors on things involving electricity ( copper on an electric circuit)