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Chemistry > chemical changes- paper 1 > Flashcards

chemical changes- paper 1 Flashcards

1
Q

What is the PH scale, what is it’s scale?

A

.pH Scale Goes From 0 to 14: measure of how acidic or alkaline a solution is.
-lower= more H+ ions concentration

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2
Q

Lower and higher PH means and neutral?

A

1)The lower the pH of a solution= more acidic it is.
2)The higher the pH of a solution,=more alkaline it is.
3) A neutral substance (e.g. pure water) has pH 7.

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3
Q

What is an indicator?

A

.indicator is a dye that changes colour depending on whether it’s above or below a certain pH.
1)indicators contain a mixture of dyes that means they gradually change colour over a broad range of pH.

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4
Q

How Can Measure the pH of a Solution using universal indicators and a PH probe?

A

1) indicators and they’re useful for estimating the pH of a solution. E.g universal indicator
Green neutral
Red acid
Blue alkali
2) pH probe attached to a pH meter can also be used to measure pH electronically.=
.probe is placed in the solution you are measuring and the pH is given digital display numerical=more accurate.

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5
Q

What is an acid?

A

An acid is a substance that forms aqueous solutions with a pH of less than 7, form H* ions in water

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6
Q

What is a base?

A

1) base is a substance with a pH greater than 7- alkali

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7
Q

What is an alkali?

A

1)An alkali is a base that dissolves in water to form a solution pH greater than 7. form OH- ions in water.

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8
Q

What is the reaction between acids and bases? - titration.

A

1.Neutralisation between acids and alkalis can be seen in terms of H+ and OH- ions like this:
2. acid neutralises a base=products neutral (indicator= neutralisation over.)
3.Neutralisation reactions strong acids, alkalis used to calculate the concentration acid or alkali by titration

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9
Q

What do you use titrations for?

A

.find out exactly how much acid is needed to neutralise quantity of alkali - or vice versa.
.data to work out concentration of the acid or alkali

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10
Q

What is the method for titrations? 5

A

1.pipette and pipette filler add a measured volume sodium hydroxide solution conical flask.
2. drops of indicator, put conical flask white tile.
3.Fill the burette with hydrochloric acid, note starting volume.
4.Slowly add acid from the burette, alkali conical flask, swirling to mix.
5.Stop adding the acid=clear. Note the final volume reading.

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11
Q

What do the measurements need to be within? (2)

A

1)repeat the whole thing a few times, Results (within 0.10 cm°).
2)calculate a mean of your results, ignoring any anomalous results.

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12
Q

What Single Indicators for Titrations do you? 3 types

A

Alkali and an acid=sudden colour change,
single indicator
-litmus (blue in alkalis and red in acids)
-phenolphthalein (pink in alkalis and colourless in acids)
-methyl orange (yellow in alkalis and red in acids).

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13
Q

1)Why do Acids Produce positive ions in Water? (dissociation)
2)what are the conditions for this?

A

.1)acids dissociate in aqueous solution
2)produce hydrogen ions, H+= don’t produce until they meet water

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14
Q

Acids Can be Strong or Weak?
How does how much H+ ions affect rate reaction?

A

.Strong acids ionise completely in water.
.All acid particles dissociate to release H* ions.

.Weak acids not fully ionise in solution.
=ionisation of a weak acid is a reversible reaction, equilibrium Between undissociated and dissociated acid only a few of the acid particles release H ions, equilibrium lies well to the left

-Reactions of acids involve the H+ ions reacting with other substances.
=concentration of H* ions is higher, the rate of reaction will be faster,
strong acids=more reactive than weak acids of the same concentration

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15
Q

How does pH is a Measure of the Concentration of Hydrogen Ions?

A

=The pH of an acid or alkali is a measure of the concentration of H* ions in the solution.
-decrease of 1 on the pH scale, the concentration of H* ions increases by a factor of 10
-+= fewer H+
- -= more H+

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16
Q

The general rule for Concentration of hydrogen ions is?

A

The pH of a strong acid is always less than the pH a weaker acid if they have the same concentration,

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17
Q

What is acid strength?

A

Acid strength ( proportion of the acid molecules ionise in water).

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18
Q

What is acid concentration?

A

.measures how much acid there is in a certain volume of water.
.pH will decrease with increasing acid concentration regardless of whether it’s a strong or weak acid

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19
Q

What are Metal Oxides and Metal Hydroxides?
what are the two formal for creating salts?
what type of reactions is it?

A

1)Bases (Some metal oxides and metal hydroxides dissolve in water.)=soluble compounds are alkalis.
2) Even bases that won’t dissolve in water will still take part in neutralisation reactions with acids.
3)ALL metal oxides and metal hydroxides react with acids to form a salt and water.

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20
Q

1)What are metal carbonates?
2)Why do Acids and Metal Carbonates Produce Carbon Dioxide and what are they?
3)how do you name salts? 2

A

1)Metal carbonates are also bases.
2)react with acids=salt+water+carbon dioxide.- nuetrailation reaction
3)ide and ate (chloride and sulphate)

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21
Q

1)How can you Make Soluble Salts Using an Insoluble Base? (3)
2)What is the method for reacting sulfric acid and copper oxide (II) (INSOUBLE BASE) to make a soluble slat?

A

1)reacting acids with insoluble bases such metal oxides, metal carbonates

1) warm sulfric acid= speed up 20 ml Bunsen burner
3) Add copper oxide to acid a bit at a time until no more reacts.=acid neutralised
4)excess solid sink bottom of the flask= ensure all acid reacted
5)filter out the excess solid=copper sulfate solution.
6)pure crystals salt= evaporate water not all (concentrated) stop heating it=leave to cool.
7)Crystals salt form filtered out of the solution and then dried for a few days while water vapour evaporates=pure crystals
Crystallise

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22
Q

1)What does an acid and metal react to give off?
2)what is the speed of the reaction indicated with?
3)How Metals React With Acids Tells You About Their Reactivity what is the equation? 3
4)what metals are most reactive with acid or least or medium?

A

1)ACID+ METAL -> SALT (ionic compound)+ HYDROGEN
2) rate at which the bubbles of hydrogen given off.
-more reactive the metal, faster reaction
-temperature change

3)
1-measuring the temperature change of the reaction acid or water over a set time
2-use the same mass and surface area of metal each time,
3-more reactive the metal, greater temperature change.

4) potassium, sodium, lithium, magnesium, calcium- loads of bubbles
Iron and zinc and tin= very few bubbles
Gold and platinum = no reaction less reactive then hydrogen

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23
Q

1)What happens when metals react with water?
2)what are the metals which react with water? 4
3)what metals don’t react with metals? 3
4) what happens with medium metals?

A

1)METAL+ WATER -> METAL HYDROXIDE + HYDROGEN
2)potassium, sodium, lithium, calcium fizzing and bubbles
3)zinc, iron, copper no reaction
4) magnesium= universal indicator will slowly turn blue as metal hydroxide is produced

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24
Q

Why do Metals Have to be Separated from their Oxides and what are the process called? 4

A

1)Metals react with oxygen to form oxides=oxidation.
2) reaction that separates a metal from its oxide is called a reduction reaction.OIL RIG
FORMATION OF METAL ORE:
Oxidation = Gain of oxygen
EXTRACTION OF METAL:
Reduction = Loss of oxygen

25
Q

Why can Some Metals can be Extracted by Reduction with Carbon? 3

A

1) metals extracted ores chemically by reduction using carbon.
2) ore=reduced as oxygen is removed from it reduction
3)carbon gains oxygen so is oxidised. oxidation
3)Metals higher carbon reactivity series extracted electrolysis expensive.

26
Q

How do you know if something can be reduced by carbon?
What happens when metals are really unreactive?

A

1)Metals below carbon in the reactivity series be extracted by reduction using carbon.
=carbon only take the oxygen away metals which are less reactive
=some metals unreactive they are in the earth as the metal itself. E.g gold

27
Q

What is the reaction called when Electrons are Transferred?

A

1) Redox Reaction. . loss of electrons is called oxidation. gain of electrons is called reduction.
2) REDuction and OXidation happen at the same time =”REDOX”.

Oil rig

28
Q

1)How are Displacement Reactions are Redox Reactions?
2)what happens when you put a reactive metal soultion in dissolved metal compound?

A

1)Displacement reactions involve one metal kicking another one out of a compound.
2)reactive metal replace less reactive metal in the compound.

29
Q

What are Ionic Equations?

A

.ionic equation only particles react and products form are shown.
Mg(s)+Zn2+(aq)->Mg2+(aq)+Zn(s)

30
Q

What are Spectator ions?

A

-don’t change In the reaction

31
Q

1)What is Electrolysis?
2)what happens to positive ions?
3)what happens to negative ions?
4)what happens when ions gain or lose electrons?

A

1)electric current passed through electrolyte ions move towards electrodes= flow of charge react= ionic compound decomposes.
Ionic conducts electricity
2) positive ions in electrolyte move towards cathode reduced. (gain electrons)
3) negative ions in electrolyte move towards anode oxidised (lose electrons)
4) ions gain or lose electrons= uncharged element discharged from electrolyte

oil rig

32
Q

1)How does Electrolysis of Molten Ionic Solids work?
2)An example of reducing lead (pb)and oxidising bromide?

A

1)ionic solid can’t be electrolysed ions fixed positions+can’t move.
2) Molten ionic compounds can be electrolysed=move freely,conduct electricity= broken up into there elements

4) Positive metal ions are reduced: pb(2+)+2e—>pb
5) Negative non-metal ions are oxidised: 2Br(-) ->Br2 +2e-
oil rig

33
Q

How do you use carbon and what is its disadvantage? 7
How can Metals can be Extracted From Their Ores Using Electrolysis?: aluminium oxide 5

A

1)more reactive carbon electrolysis be used to extract
2)-graphite- unreactive= conduct electricity
-high temperatures= will start to recat carbon in graphite so get worn away
-Expensive
-replace electrodes
-energy (heat)
-electricity

1)Aluminium=extracted from ore (bauxite) Bauxite contains aluminium oxide
2) Aluminium oxide=very high melting temperature ( giant ionic lattice structures)=mixed cryolite=lower melting point.= saves money and energy (disrupted ionic lattice)
3) molten mixture=contains free ions -conduct electricity.
4) positive Al3+ ions attracted negative electrode (vessel itself) pick up three electrons=neutral aluminium atoms. sink bottom tank.
5)negative O2- ions attracted positive electrode lose two electrons. neutral oxygen= O2

34
Q

How do you test for gas product after electrolysis of aqueous solutions? Chlorine, oxygen, hydrogen

A

.Chlorine bleaches damp litmus paper, turning it white.
.Hydrogen makes a “squeaky pop” with a lighted splint.
.Oxygen will relight a glowing splint.

35
Q

reactivity series?

A

Please- potassium
Stop- sodium
Cum- calcuium
Monkeys- magnesium
And- aluminum
Cum- carbon
Zebras- zinc
Into- iron
Hot- hydrogen
Countries- copper
Signed- silver
God- gold

36
Q

Reactivity of metals and what does it mean if a metal is more reactive?

A

When metals react with other substances, the metal atoms lose electrons to form positive ions.

-the more vigorous its reactions are
-the more easily it loses electrons in reactions to form positive ions (cations)

37
Q

Electrolysis: copper chloride?
(aqauose)

A
  1. Add about 50cm° of copper chloride solution to a beaker.
  2. insert electrodes making sure the electrodes don’t touch.
  3. Attach crocodile leads to the electrode and connect the rods to DC
  4. Set power supply to 4V and switch the power supply on.
  5. Using the forceps hold the litmus paper near the positive electrode.
  6. After a few minutes turn the power supply off-observe the negative electrode= copper
  7. Record observations at the electrodes.
38
Q

Electrolysis: sodium chloride? 5
(aqueous)

A
  1. Add about 50cm° of sodium chloride solution to a beaker.
  2. insert electrodes making sure the electrodes don’t touch.
  3. Attach crocodile to electrode (graphite) and connect the rods to the DC.
  4. forceps litmus paper positive electrode.
  5. After a few minutes turn the power supply off observe the negative electrode. There should be effervescence= hydrogen
39
Q

Results of electrolysis: sodium chloride and copper chloride?

A

-less reactive will be shown at the cathode

40
Q

Half equations?
redox reactions?

A

.

41
Q

Cathode? more and less reactive

A

-metal is produced at the cathode if it is less reactive than hydrogen
-hydrogen is produced at the cathode if the metal is more reactive than hydrogen

42
Q

Anode? 4

A

1-Oxygen is produced (from hydroxide ions),
2-unless halide ions (chloride, bromide or iodide ions) are present.
3-negatively charged halide ions lose electrons
4-form the corresponding halogen (chlorine, bromine or iodine)

43
Q

1)what type of conductor is water and what does it contain?
2)how are these ions formed from the water?
3)what happens when Electrolysis of acidified water? (water is acidified with dilute sufic acid)

A

1)Water is a poor conductor of electricity, but it does contain some hydrogen ions, H+, and hydroxide ions, OH-.
2)formed: small proportion of water molecules naturally dissociate.

3)water is acidified with a dilute sulfuric acid:
1)H+ ions are attracted to the cathode, gain electrons=hydrogen gas
2)OH- ions are attracted anode, lose electrons=oxygen gas

44
Q

1)what is in Electrolysis of dissolved ionic compounds of the electroye ? (aqueous)
2)what do the ions do in the electrolyte?

A

1)Electrolyte:
1)hydrogen ions from the water (positive)
2)positive ions from the compound
3)hydroxide ions from the water (negative) 4)negative ions from the compound

2) ions compete at each electrode to gain or lose electrons.
(creating a flow of charge)

45
Q

How to write symbol equations for reactions of metals in water?

A
  1. 2 of the metal
  2. 2 water molecules
  3. form metal hydroxide e.g LiOH (form 2)
  4. with an extra hydrogen with little two as it is diatomic
46
Q

1)Alkalis?
2)bases?
3)can bases be insoluble or soluble?
4)what can you use insouble bases for? 2 insoluble bases

A

1)Alkalis (always soluble) all bases
2)Bases are not all alkalis they are things which nutrasises an acid
3)bases can be insoluble
4)Insoluble bases react with acid form a salt=
Metal oxide or metal carbonate

47
Q

Litmus paper?

A

-red in acid
-blue in neutral and alkali

48
Q

How are salts made?
What is a salt?
How do you name the 3 common salts?

A

-metal or base react with acid
-ionic compounds
First names= Metal in base
Second named= ide and other acids are ate

49
Q

what are Ionic compounds made up of?
what can you do to overcome this? 2

A

Strong electrostatic forces of attraction between positive and negative ions ionic bonds
=ions not free to move can’t split

=molten- heat high temperature
=aquaous- dissolve in water

50
Q

what does it mean when something is Discharged, when does this happen?

A

electrolysis when the ions reach the electrodes they ethier gain or lose electrons
-discharge= what’s formed

51
Q

Halide ions?

A

Two atoms of halide all the time
-> halogen
Bromide->bromine

52
Q

Deciding what is produced where in molten compunds?

A
53
Q

Aluminium oxide-extracting ores half equations?

A
54
Q

What happens when you use electrolysis with aqueous solutions?

A

-dissolve in water so you also have other ions H+ and -OH
Hydrogen and hydroxide ions

55
Q

What are the discharge rules in aqueous solutions? 3
what is the equation when the hydroxide is discharged?

A

1.Most reactive cations (metals or hydrogen) stay in solution-Reactivity series
2.If there is a halide ion it will be dicarged all the time, chloride -> chlorine if you don’t= e.g hydroxide will be discharged
3.hydroxides discharge= oxygen and water

56
Q

What happen at the anode and at the cathode?

A
57
Q

Hydrogen: cation dishacrge half equation?

A
58
Q

Anion dishacrge of chlorine?

A
59
Q

Anion dishacrge: oxygen?

A

Chemistry (16 decks)

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