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Chemical Changes Flashcards

1
Q

What is a base?

A

bases are compounds that can neutralise an acid

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2
Q

What is an alkali?

A

alkali’s are bases that are soluble in water

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3
Q

What are the acid general equations?

A

acid + base –> salt + water
acid + metal –> salt + hydrogen
acid + metal oxide –> salt + water
acid + metal hydroxide –> salt + water
acid + metal carbonate –> salt + carbon dioxide + water
acid + ammonia solution –> ammonium salt + water

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4
Q

What does acid + base -> ?

A

salt + water

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5
Q

What does acid + metal -> ?

A

salt + hydrogen

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6
Q

What does acid + metal oxide ->

A

salt + water

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7
Q

What is a neutralisation reaction?

A

an acid and alkali reaction

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8
Q

How to remember the neutralisation reactions?

A
  • acid = proton donor (hydrogen ion)
  • remember all reactions create a salt
  • remember law of conservation of atoms (if carbon is in reactants, it must be in products)
  • if hydrogen and/or oxygen are reactants, water will be a product
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9
Q

What is the reactivity series?

A

Please Stay Late Cause My Awesome Cat Zinc Is Hyper Chaotic Silly Girl

  • Potassium
  • Sodium
  • Lithium
  • Calcium
  • Magnesium
  • Aluminium
  • Carbon -!
  • Zinc
  • Iron
  • Hydrogen
  • Copper
  • Silver
  • Gold
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10
Q

What are weak acids?

A

Weak acids = acids that partially ionise/dissociate, releasing H^+ ions

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10
Q

What is a salt?

A

When an hydrogen leaves an acid, and bonds with metals.

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10
Q

What are need to know ions?

A

NO3^2- : nitrate ions
SO4^2- : sulfate ion
NH4^+ : ammonium ion
CO3^2- : carbonate ion

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10
Q

Are hydroxide ions alkali or acidic?

A

OH- = alkali

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10
Q

What are strong acids?

A

acids that completely ionise/dissociate, releasing H^+ ions

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11
Q

Examples of strong acids?

A

HCl
H2SO4
HNO3

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11
Q

Examples of weak acids?

A

ethanoic acid = vinegar
citric acid
carbanoic (rain water, fizzy drinks)

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12
Q

What does acid + metal hydroxide -> ?

A

salt + water

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13
Q

What does acid + metal carbonate -> ?

A

salt + carbon dioxide + water

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14
Q

What does acid + ammonia solution -> ?

A

ammonium salt + water

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15
Q

How do you measure the pH of a solution?

A

Indicator- dye that changes colour depending on pH

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16
Q

What is an example of a wide range indicator?

A

universal indicator
- contains a mixture of dyes, gradually change colour for a wide range of pH
- useful estimating pH of a solution

pH probe
- attached to a pH meter, electronic measurement
-numerical result, more accurate

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17
Q

What ions do alkali’s form in water?

A

OH^-

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18
Q

What ions do acid produce in water?

A

H^+ (hydrogen ions)

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19
Q

Is the ionisation of a weak acid a reversible reaction?

A

Yes, it sets up an equilibrium between the undissociated and dissociated acid. (less H^+ ions are released, equilibrium lies to the left)

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20
How does concentration of H^+ ions affect rate of reaction?
High concentration: rate of reaction is faster, strong acids are more reactive than weak acids of same concentration.
21
What is pH?
a measure of concentration of H^+ ions
22
If the pH scale decreases by 1, how does the concentration of H+ ions change?
increases by a factor of 10 (pH 4 = 10x concentration of H+ than pH 5)
23
If the pH scale decreases by 2, how does the concentration of H+ ions change?
increases by a factor of 100
24
What is the formula for the factor of H+ ion concentration when pH changes?
Factor H+ ion concentration changes by = 10 ^-x x= difference in pH
25
What does acid strength tell you?
What proportion of the acid molecules ionise in water
26
What does the concentration of an acid tell you?
How much acid there is in a certain volume of water
27
How is reactivity determined in metals?
By how easily they lose electrons, forming positive ions
28
How is the speed of a reaction indicated by?
the rate at which hydrogen bubbles are given off
29
What is the relationship between reactive metals and the rate of reaction?
The more reactive the metal, the faster the reaction (Pottasium, Sodium, Lithium react explosively- more reactive) (magnesium, zinc, iron react less violently- less reactive) (copper- barely no reaction)
30
How can you investigate the reactivity of metals?
- measuring the temperature change of the reaction (with acid or water), over set period of time - if same mass + SA of metal, the more reactive the metal= greater the temperature change will be
31
What does water + metal -> ?
Metal oxide + Hydrogen more reactive metals will react, less reactive metals won't react
32
What is a reduction reaction?
A type of oxidation reaction - a reaction that separates a metal from its oxide
33
What is an oxidation reaction?
- the loss of electrons - gain of oxygen
34
What is a reduction reaction?
- the gain of electrons - the loss of oxygen
35
What type of reaction is the formation of a metal ore?
Oxidation
36
What type of reaction is the extraction of metal?
Reduction
37
How can metals be extracted from their ores (chemically)?
Reduction with carbon: - ore reduced (looses oxygen) - carbon oxidised, CO2 (gains oxygen)
38
What determines if the metal can be extracted with carbon or not?
The position of the metal in the reactivity series
39
How are metals more reactive than carbon extracted from their ores?
Electrolysis (expensive)
40
How are metals less reactive than carbon extracted from their ores?
Using reduction by carbon (iron oxide in a blast furnace = iron) - Carbon can only rake oxygen away from metals which are less reactive than itself
41
How is gold mined?
Found in the earth as itself, so unreactive - mined in elemental form
42
What is a displacement reaction?
When a more reactive metal will displace a less reactive metal from its compound
43
In displacement reactions, what always happens to the metal ion?
The metal ion always gains electrons + is reduced
44
What is a spectator ion?
ions that don't change in the reaction
45
What is an ionic equation?
An equation that just focuses on the substances being oxidised and reduced
46
What is Electrolysis?
A process that uses an electrical current to cause a reaction
47
What is the process of Electrolysis?
-An electric current is passed through an electrolyte, ions move to electrodes + react (compound is dissolved) - Positive ions move towards the cathode + gains electrons (reduced) -Negative ions move towards the anode + lose electrons (oxidised) -Creates flow of charge in electrolyte as ions travel to electrode -As ions gain or lose electrons, they form uncharged elements and are discharged from the electrolyte
48
What is an Electrolyte?
A molten or dissolved ionic compound - can conduct electricity - electrode is submerged in electrolyte
49
What is an Electrode?
a solid that conducts electricity, is submerged in an electrolyte
50
What is a cathode?
negative electrode
51
What is an anode?
positive electrode
52
Why can't an ionic solid be electrolysed?
Ions are in fixed position, cannot move
53
How are molten ionic liquids broken up into their elements using electrolysis?
-Positive metal ions are reduced to the element at the cathode -Negative non-metal ions are oxidised to the element at the anode
53
Why can molten ionic compounds be electrolysed?
Ions can move freely, conduct electricity
54
How can metals be extracted from their ores using electrolysis? (EG. Aluminium)
-Aluminium is extracted from Bauxite (ore, contains aluminium oxide) by electrolysis. - Aluminium oxide-> High melting temp, mixed w Cryolite to lower melting point - molten mixture contains free ions-> conducts electricity - Positive Al^3+ ions -> negative electrode, become neutral Al atoms, sink to bottom of tank - Negative O^2- ions attracted to positive electrode, lose 2 electrons, neutral O atoms combine, forming O2 molecules -
55
What is Cryolite?
- aluminium based compound, lower melting point than aluminium oxide
56
What is the process of Electrolysis of Aqueous solutions?
- In aqueous solutions, H+ and OH- ions are also present from the water (as well as the ionic compound) - Cathode: hydrogen gas may be produced if H+ and metal ions are present and the metal ions form a elemental metal more reactive than hydrogen (ie sodium ions). If they produce a elemental metal less reactive (copper ions), solid layer of pure metal produced - Anode: if OH- and Halide ions (Cl-, Br, I-) are present, molecules of the halide are produced. If no halide present, OH- ions discharged, oxygen formed
57
What is the neutralisation reaction between Hydrogen and Hydroxide ions?
H+ + OH- -> H2O
58
How do you test for Chlorine?
Damp piece of litmus paper, bleaches it, turning it white
59
How do you test for Hydrogen?
Take a test tube with the gas inside, take a lit splint place inside, if 'squeaky pop' sound is made, gas is present
60
How do you test for Oxygen?
Take a test tube with the gas present, take a splint and light it, blow it out ( a glowing split), place glowing splint inside if gas is present the splint will relight
61
What is acid + metal hydroxide --> ?
salt + water
62
What is acid + metal carbonate --> ?
salt + carbon dioxide + water
63
What is acid + ammonia solution --> ?
ammonium salt + water

Chemistry (13 decks)

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