Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Level 2 Science > Chemical Changes > Flashcards

Chemical Changes Flashcards

You may prefer our related Brainscape-certified flashcards:
Certified Sommelier Exam (CMS 2) flashcards Biology 101 flashcards
1
Q

what is thermal decomposition?

A

process in which substance broken down into 2 or more simpler substances by the effect of heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is combustion?

A

combination of a substance with oxygen in presence of heat (releases a lot of energy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is electroplating?

A

process in which a substance is coated with a metal with the passage of an electric current

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is electrolysis?

A

chemical decomposition of substances with passage of an electric current

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are acids?

A

substance that produces hydrogen ions (acidic properties) in aqueous solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are 4 common acids?

A

hydrochloric acid (HCl)
nitric acid (HNO₃)
sulfuric acid (H₂SO₄)
phosphoric acid (H₃PO₄)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the basicity of an acid?

A

number of hydrogen ions which can be produced by one molecule of the acid (monobasic, dibasic, tribasic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what are 2 properties of acids? (taste/texture and pH)

A

sour taste
pH <7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what are the effects of acids on litmus paper and universal indicator?

A

turns blue litmus paper red (no effect on red litmus paper)
turns universal indicator from green to yellow/orange/red depending on pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

why do acids only display their properties when added to water?

A

acids produce hydrogen ions in aqueous solutions, which gives acids their properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what are salts?

A

ionic compounds formed when metal/ammonium ions replace 1 or more hydrogen ions of an acid (e.g. KCl)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the equation for acids and reactive metals?

A

acid + metal –> salt + hydrogen
forms salt + hydrogen gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what are the 2 observations of acid-metal reactions?

A

effervescence of colourless and odourless gas
grey solid (metal) dissolves to form colourless solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the equation for acids and metal carbonates?

A

acid + metal carbonate –> salt + water + carbon dioxide
forms salt + water + carbon dioxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are the 2 observations of acid-metal carbonate reactions?

A

effervescence of colourless and odourless gas
white solid (metal carbonate) dissolves to form colourless solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are metal carbonates?

A

ionic compounds containing metal cation and carbonate ion (e.g. CuCO₃)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the equation for acids and bases?

A

acid + base –> salt + water
forms salt + water only
neutralisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what are bases?

A

metal oxides/hydroxides that react with acids to form salt and water only

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

how do you test for hydrogen gas (colourless/odourless)?

A

place lighted splint at mouth of test tube

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is the observation of the test for hydrogen gas?

A

hydrogen will extinguish lighted splint with ‘pop’ sound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

how do you test for carbon dioxide gas (colourless/odourless)?

A

bubble gas into limewater (aqueous calcium hydroxide)

22
Q

what is the observation of the test for carbon dioxide gas?

A

carbon dioxide will form white precipitate with limewater

23
Q

how do you test for ammonia gas (colourless/pungent)?

A

damp red litmus paper

24
Q

what is the observation of the test for ammonia gas?

A

ammonia gas will turn the damp red litmus paper blue

25
Q

what are alkalis?

A

substance that produces hydroxide ions (alkaline properties) in aqueous solution

bases that are soluble in water

26
Q

what are 4 alkalis?

A

sodium hydroxide (NaOH)
calcium hydroxide [Ca(OH)₂]
aqueous ammonia [NH₃(aq)]
potassium hydroxide (KOH)

SCAP hydroxide [ammonia is special :)]

27
Q

what are 4 insoluble bases?

A

magnesium oxide (MgO)
lead(II) oxide (PbO)
iron(III) oxide (Fe₂O₃)
zinc oxide (ZnO)

ZILM oxide

28
Q

what are 2 properties of alkalis? (taste/texture and pH)

A

bitter taste, soapy feel
pH 7>

29
Q

what are the effects of alkalis on litmus paper and universal indicator?

A

turns red litmus paper blue (no effect on blue litmus paper)
turns universal indicator from green to blue/violet depending on pH

30
Q

why are both acids and alkalis good conductors of electricity in aqueous solutions?

A

they contain mobile ions

31
Q

what is the equation for alkalis and acids?

A

alkali + acid –> salt + water
forms salt + water only
neutralisation

32
Q

what is neutralisation?

A

process in which hydrogen ions (H⁺) from acids and hydroxide ions (OH⁻) from alkalis react to form water

33
Q

what is the ionic equation for neutralisation?

A

H⁺(aq) + OH⁻(aq) —> H₂O(l)

34
Q

what is the equation for alkalis heated with ammonium salts?

A

alkali + ammonium salt -(heat)-> salt + water + ammonia
produces salt + water + ammonia gas

35
Q

what are ammonium salts?

A

salts containing ammonium ions (e.g. ammonium nitrate)

36
Q

what is the concentration of a solution?

A

the amount of a solute dissolved in a unit volume of solution

37
Q

what are concentrated and diluted solutions?

A

concentrated: large number of particles of a substance in a fixed volume of water
diluted: small number of particles of a substance in a fixed volume of water

38
Q

what is a saturated solution?

A

solution formed when the maximum amount of solute has been dissolved in a fixed volume of solvent at a fixed temperature

39
Q

what is the concentration of ions in acids?

A

higher concentration of hydrogen ions, lower concentration of hydroxide ions

40
Q

what is the concentration of ions in neutral solutions?

A

contains equal number of hydrogen and hydroxide ions

41
Q

what is the concentration of ions in alkalis?

A

higher concentration of hydroxide ions, lower concentration of hydrogen ions

42
Q

what are 2 ways to measure pH?

A

indicators (chemical compounds)
pH meter

43
Q

what is an indicator?

A

substance which changes colour depending on whether a solution is acidic/alkaline

44
Q

what is a pH meter?

A

digital instrument which gives a numerical pH value by measuring pH electrically

45
Q

why is a pH meter more accurate and reliable than indicators?

A

we can only approximate the pH values of substances from the colour of indicators

46
Q

what are 3 types of indicators?

A

methyl orange
litmus
phenolphthalein

47
Q

what are the properties of methyl orange? (colour in acids/alkalis, pH which colour changes)

A

in acidic solutions: red
pH which colour changes: 3-5
in alkaline solutions: yellow

48
Q

what are the properties of litmus? (colour in acids/alkalis, pH which colour changes)

A

in acidic solutions: red
pH which colour changes: 5-8
in alkaline solutions: blue

49
Q

what are the properties of phenolphthalein? (colour in acids/alkalis, pH which colour changes)

A

in acidic solutions: colourless
pH which colour changes: 8-10
in alkaline solutions: pink

50
Q

what are 3 beneficial effects of chemical changes?

A

decomposition of dead organisms breaks down unwanted matter and releases nutrients back to the earth
cooking food
household detergents for cleaning
medicines, insecticides
jet fuel combustion to produce energy to move planes

51
Q

what are 3 harmful effects of chemical changes?

A

air pollution from combustion harmful to health (acid rain, corrodes buildings, destroys aquation life)
iron structures like bridges rust, becomes corroded and unsafe
decomposition leads to wastage of food supplies and resources

52
Q

what are 3 unreactive metals?

A

copper
gold
silver

Level 2 Science (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions