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Physics And Chemistry 2024 Year 10 > C5-Chemical Changes > Flashcards

C5-Chemical Changes Flashcards

(104 cards)

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1
Q

What are acids

A

Acids produce hydrogen ions (H*) in aqueous solutions. They have a pH range of 0-6.

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2
Q

What are alkali

A

Alkalis produce hydroxide ions (OH*) in aqueous solutions. They have a pH range of 8-14.

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3
Q

What is crystallisation

A

A separation technique used to produce solid crystals from a solution by evaporating the solvent.

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4
Q

What is a displacement

A

A chemical reaction in which a more reactive element displaces a less reactive element from its compound.

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5
Q

What is filtration

A

A separation technique used to separate solids from liquids

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6
Q

What is nuetralisation

A

The reaction when a acid and a base react ro form water and a salt

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7
Q

What is oxidation

A

A reaction involving the gain of oxygen.Oxidation is the loss of electrons

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8
Q

What is the pH scale

A

The pH scale, from 0 to 14, is a measure of the acidity or alkalinity of a solution, and can be measured using universal indicator or a pH probe.

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9
Q

What is a redox reaction

A

A reaction in which both oxidation and reduction occur simultaneously

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10
Q

What is reduction

A

A reaction involving the loss of oxygen. Reduction is the gain of electrons.

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11
Q

What is reduction with carbon

A

Metals less reactive than carbon can be extracted from their oxides by reduction with carbon.

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12
Q

What is a strong acid

A

A strong acid is completely ionised in aqueous solution. Examples of strong acids are hydrochloric, nitric and sulfuric acids.

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13
Q

What is the reactivity series

A

Metals are arranged in order of their reactivity in a reactivity series.
This can be used to predict products from reactions.

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14
Q

What is a titration

A

A technique used where a solution of known concentration is used to determine the concentration of an unknown solution.

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15
Q

What is a universal indicator

A

A mixture of dyes that changes colour gradually over a range of pH and is used in testing for acids and alkalis.

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16
Q

What is a weak acis

A

A weak acid is only partially ionised in aqueous solution. Examples of weak acids are ethanoic, citric and carbonic acids.

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17
Q

Two reasons why a probe may be more reliable then using a indicator

A

More accurate results,determining the colour of the indicator is subjective

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18
Q

When a acids concentration is increased what happens to its pH

A

Its increases.
For example if it went from ph 6 to ph5 you times by 10 the concentration

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19
Q

Acid+metal oxide

A

Salt+water

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20
Q

What is a nuetralisation reaction

A

When a positive hydrogen ions from the acid react with the negative hydroxide ions from the acid react with the negative hydroxide ions from the alkali

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21
Q

Acid + metal hydroxide

A

Salt + water

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22
Q

Acid + metal carbonate

A

Salt +water+carbon dioxide

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23
Q

Why do we find pure gold in the ground, but not pure iron?

A

Gold is unreactive, so doesn’t react with any other elements
Iron is reactive enough to react with oxygen so is oxidised to iron oxide

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24
Q

Reaction of lithium with water

A

Fizzes/bubbles (hydrogen gas produced)
- Floats and moves around the surface

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25
Reaction of sodium with water
Fizzes / bubbles more vigorously - Floats and moves around more - Makes a ball shape
26
Reaction of pottasium with water
Fizzes vigorously & ignites to produce a lilac flame - Floats and moves around
27
Reaction of magnesium with water
No reaction.Fizzes in dilute acid
28
What are spectator ions
Ions that dont change, so we remove them lonic equations only show the particles that react in the reaction
29
What salt does Hydrochloric acid make
Chloride salt
30
What salt does Sulfuric acid make
Sulfate salt
31
What salt does Nitric acid make
Nitrate salt
32
Acid + alkali
Salt + water
33
Acid + base
Salt + water
34
What is an alkali
A soluble metal hydroxide
35
What is a base
insoluble metal hydroxides & all metal oxides
36
Process of crystallisation
Gently warm the sulfuric acid in a beaker,Add some copper oxide & stir,Keep adding until no more reacts, shown by excess solid at the bottom,Filter to remove excess copper oxide,Heat gently using a water bath until you start to see solid appear,Leave the solution to crystallise then pat dry with filter paper if needed
37
What do acids contain
Hydrogen ions
38
What do alkalis contain
Hydroxide ions
39
Examples of strong acids
Hydrochloric acid,sulfuric acid,nitric acid
40
Examples of weak acids
Citric acid,carbonic acid,ethanoic acid
41
What is a metal ore
When there is enough of a metal or metal compound in a rock to make it worth extracting the metl
42
Describe how an acid or alkali can be weak or strong.
Acids and alkalis can be strong or weak depending on how much they ionise in water. Strong acids (e.g., HCl, H₂SO₄) and strong alkalis (e.g., NaOH, KOH) fully ionise, releasing all their H⁺ or OH⁻ ions, making them highly reactive and corrosive, with extreme pH values (0-2 for acids, 12-14 for alkalis). Weak acids (e.g., CH₃COOH) and weak alkalis (e.g., NH₃) partially ionise, meaning only some molecules release ions, resulting in a higher pH (3-6 for acids, 8-11 for alkalis) and milder reactions.
43
Define a salt
A salt is a compound formed when the hydrogen ion (H⁺) from an acid is replaced by a metal ion or another positive ion. Salts are typically produced in neutralisation reactions between acids and bases, metals, or carbonates.
44
Why does a displacement reaction occur
A displacement reaction occurs because a more reactive metal displaces a less reactive metal from a compound. This happens because the more reactive metal has a stronger tendency to lose electrons and form positive ions, while the less reactive metal gains electrons and is displaced from its compound
45
Example of a alkali
Sodium hydroxide
46
Example of something nuetral
Water
47
Example of a base
Copper oxide
48
Example of an acid
Hydrogen acis
49
describe how universal indicator can be used to classify a chemical as acidic or alkaline.
Acids-red,organge yellow colour Alkali-blue/purple
50
How does carbon reduce metal oxides
Carbon removes oxygen from metal oxides, forming carbon monoxide or carbon dioxide.
51
Example of metal reducing oxygen
Lead + oxide > lead + carbon dioixde 2PbO + C >2Pb+ CO2 Heat
52
When is hydrogen used instead of carbon?
Hydrogen is used for elements that are less reactive than carbon and hydrogen
53
Why can’t carbon reduce very reactive metals like aluminium?
Aluminium is more reactive than carbon, so carbon isn't strong enough to remove its oxygen. Instead, aluminium is extracted using electrolysis.
54
What are the most reactive metals in the reactivity series used for
used in batteries and aircraft because of their lightweight and reactive properties.
55
What are moderatley reactive metals in the reactivity series used for
used in construction and protection against rust.
56
What are unreactive metals in the reactivity series used for
for jewellery and technology because they don’t corrode.
57
Metal + oxygen >
Metal oxides
58
Pottasium reaction with water
Violent
59
Sodium reactiin with water
Very quick
60
Lithium reaction with water
Quick
61
Calcium reaction with water
More slow
62
Calcium reaction with acid
Very quick
63
Magnesium reaction with acid
Quick
64
Zinc reaction with acid
Fairly slow
65
Iron reaction with acid
More slow
66
Copper reaction with acid
Very slow
67
What does OILRIG mean
Oxidisation is Loss and Reduction Is Gain
68
What happens if sodium is oxidised
Lost an electron,making it have a 1+ charge Na>Na+ +e-
69
Example of a redox reaction
e.g. 2HC + Mg -> MgCl2 + H2 • magnesium: Mg -> Mg'so ionic equation is Mg -> Mg2+ + 2e, Mg has lost electrons so Mg has been oxidised hydrogen: 2H2 -> H,, so ionic equation is 2H+ + 2e -> H,, H has gained electrons, so H has been reduced • because magnesium has been oxidised and hydrogen has been reduced in the same reaction, this is a redox reaction
70
What are acids nuetralised by
Alkalis,bases,insoluble metal hydroxides and metal oxides to form salt and water
71
What are acids in aqueous solutions
H+ ions
72
What are alkalis in aqueous solutions
OH-
73
Ionic equation for any nuetralisation reaction
H+ + OH- -> H2O
74
How to carry out titration
Wash burette using dilute hydrochloric acid and then water 2. Fill burette to 100cm' with acid with the meniscus' base on the 100cm' line 3. Use 25cm' pipette to add 25cm' of alkali into a conical flask, drawing alkali into the pipette using a pipette filler 4. Add a few drops of a suitable indicator to the conical flask (eg: phenolphthalein which is pink when alkaline and colourless when acidic) 5. Add acid from burette to alkali until end-point is reached (as shown by indicator) 6. The titre (volume of acid needed to exactly neutralise the acid) is the difference between the first (100cm') and second readings on the burette 7. Repeat the experiment to gain more precise results
75
What does 1 dm^3 equal
1000cm ^3
76
What happens the Ph when an acid is increased
Acids release H⁺ ions, increasing their concentration. More H⁺ ions means the solution becomes more acidic, so the pH decreases.
77
What happens to the pH when a alkali is added
Alkalis release OH⁻ ions, which neutralise H⁺ ions, reducing their concentration. Fewer H⁺ ions means the solution becomes less acidic (or more alkaline), so the pH increases.
78
How to increase accuracy of titration
Several consistent readings,first titration must be rough estimate and then repeat and you should get similar results.then work out the concordant disregarding anomalous results
79
What colour is litmus in alkalis and in acids
Blue in alkalis,red in acids
80
What colour is phenophthalein in alkalis and acids
Pink in alkalis,colourless in acids
81
What colour is methyl orange in alkalis and acids
Yellow in alkalis and red in acids
82
Is the ionisation of weak acids reversable
Yes,which sets up an equilibrium between the undissociated and dissociated acid.
83
What happens when the pH scale decreases by 1
The concentration of H+ ions increases by a factor of 10.When its 2 it increases by 100
84
Equation for concentration of ions
Factor H+ ion concentration changes by 10=-x the minus x is difference in pH.
85
What does acid strength tell us
What proportion of the acid molecules ionise in water
86
What does rhe concentratjon of a acid tell us
Measures how much acid there is in a certain volume of water.Concentration is basically how watered down your acid is.
87
Method of making soluble salts from insoluble bases
Add the Insoluble Base to the Acid: Mix the acid (e.g., hydrochloric acid) with the insoluble base (e.g., copper(II) oxide). React to Form a Salt: The acid reacts with the base to form a salt and water. Filter the Solution: After the reaction, filter out any leftover solid base. Evaporate the Water: Heat the solution to evaporate the water, leaving salt crystals behind. Dry the Salt: Dry the salt crystals using filter paper or an oven.
88
Reactivity series list
Pottasium Sodium Lithium Calcium Magnesium Carbon Zinc Iron Tin Hydrogen Copper
89
Hw do we know the speed of reactin when metals react with acids
Indicated by the rate at which the bubbles of hydrogen are given off
90
evaluate how universal indicator or a data logger can be used to determine the approximate pH of a solution.
Universal Indicator: Changes colour to show pH, compared to a colour chart. Quick, cheap, and easy to use. Less accurate – colour interpretation is subjective. ✅ Data Logger with pH Probe: Gives a numerical pH reading, displayed digitally. Highly accurate and objective, no human error in interpretation. Expensive and requires calibration, making it harder to use in schools.
91
Describe the relationship between acids and alkalis
Acids and alkalis are opposites on the pH scale. Acids release hydrogen ions (H⁺) when dissolved in water. Alkalis release hydroxide ions (OH⁻) when dissolved in water. Neutralization occurs when an acid and an alkali react, forming water and a salt. Acids have a pH less than 7, while alkalis have a pH greater than 7. Strong acids and alkalis completely dissociate in water, while weak acids and alkalis only partially dissociate.
92
Formula to explain how the concentration of hydrogen ions relates to pH number
pH=-log[H]^+
93
Example question of explaining how the concentration of hydrogen ions relates to pH number
If the concentration of H+ is 1x10-7 Ph=7
94
Ammonium acid + acid
Ammonium salt +water
95
When you add a acid to water what happens
It releases H+ atoms
96
What happens when you add a alkali to water
It releases OH- atoms
97
Formula for nitric acid
HNO3
98
Formula for hydrochloric acid
Hcl
99
Formula for sulfuric acid
H2SO4
100
What is effervescence
fizzing or bubbling because a gas is being released.
101
How do you make a soluble salt
Mixing a insoluble base and a acid
102
Formula for calcium carbonate
CaCO3
103
How can an acid be concentrated
A concentrated acid/alkali has a large amount of solute (acid or alkali) dissolved in a small volume of water.
104
How can an acid be dilute
A dilute acid/alkali has a small amount of solute dissolved in a large volume of water.

Physics And Chemistry 2024 Year 10 (9 decks)

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