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chemical changes Flashcards

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1
Q

what is the principle of chemical reaction

A

atoms cannot be never created nor destroyed in a chemical reaction (like how energy cannot be created nor destroyed)

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2
Q

what is the conservation of mass equations

A
  • the left side of the equation ALWAYS EQUALS the right side of the equation
  • chemical reactions involve the rearrangement of existing atoms, there is no loss or gain of atoms (left side = right side of equation)
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3
Q

what is the difference between physical and chemical reactions

A

Physical:
- no new substances are formed
- can usually be reversed
chemical:
- one or more new substances are formed
- not easily reversed

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4
Q

what is the word equation

A

reactant + reactant → product

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5
Q

what is the definition of matter

A

anything that has both mass and volume

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6
Q

what is the definition of composition

A

the types and amounts of simpler substances that make up a sample of matter

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7
Q

what is the definition of properties

A

the characteristics that give each substance a unique identity

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8
Q

what are physical properties

A
  • properties a substance shows by itself without interacting with another substance
  • color, melting point, boiling point, density
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9
Q

what are chemical properties

A
  • properties a substance shows as it interacts with, or transforms into, other substances
  • flammability, corrosiveness
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10
Q

what are the states of matter

A
  • solid
  • liquid
  • gas
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11
Q

what are the properties of solid

A
  • has a fixed shape and volume.
  • may be hard or soft, rigid or flexible
  • particles are closed together and organised
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12
Q

what are properties of liquid

A
  • has a varying shape that conforms to the shape of the container(no fixed shape)
  • has a fixed volume
  • has an upper surface
  • particles are close to each other but disorganised
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13
Q

what are indicators of a chemical change

A
  • burning/fire
  • bubbles/fizzes (effervescent)
  • temperature change (without heating or cooling)
  • explosion
  • colour change
  • odour change
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14
Q

what are indicators of a physical change

A
  • phase changes (changes in state of matter)
  • mixtures (usually)
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15
Q

what are properties of gas

A
  • no fixed shape
  • no fixed volume
  • therefore does not have a surface.
  • particles are far apart and disorganised
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16
Q

what are the 2 categories of chemical changes

A
  • reactions in which two or more substances chemically combine to form one or more new substances (eg. carbon burns in the presence of oxygen)
  • reactions in which a substance breaks down into two or more new substances
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17
Q

what is combustion

A
  • object breaks down into any substance(s), (not fixed) → needs heat
  • a substance is heated in the presence of oxygen, heat and light is given out e.g. fossil fuels burnt to create energy
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18
Q

what is thermal decomposition

A

the process of an object that breaks down into two or more simpler substances

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19
Q

what is oxidation

A
  • does not need heat
  • gain of oxygen (e.g. Ca (calcium) gained O (oxygen) and has been oxidised to form CaO)
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20
Q

acid + base =

what is neutralisation with a base

A

acid + base = salt + water (only)

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21
Q

how to find the name of an ion

A

the element name + ‘ide’ (e.g. chlorine ion = chloride)

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22
Q

what is the definition of electrolysis and electroplating

A

using electricity to move the atoms/ions in metal from one place to another

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23
Q

all acids are __ when dissolved in water

A

H⁺

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24
Q

what is the hazards of acids and alkalis

A
  • some acids and alkalis may be toxic or corrosive
  • warning symbols: acute toxicity, corrosives
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25
Q

what are some lab equipment that helps with identifying the alkalis and acids

A
  • litmus paper → determines only if the substance is acidic or alkaline
  • pH paper → gives a more precise reading (pH value) than litmus paper
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26
Q

what does pH stand for

A

pH: p = potential/power (of hydrogen), H = hydrogen ion

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27
Q

what are some common acids used in the lab + chemical formula

A
  • hydrochloric acid - HCl
  • sulfuric acid - H₂SO₄
  • nitric acid - HNO₃
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28
Q

what is the name of the salt produced from hydrochloric acid (HCl)

A

(metal) chloride

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29
Q

what is the name of the salt produced from sulfuric acid (H₂SO₄)

A

metal sulfate

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30
Q

what is the name of the salt produced from nitric acid (HNO₃)

A

metal nitrate

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31
Q

what are common features in acids

A
  • all acids are sour
  • all acids contain hydrogen (therefore, the chemical formula always starts with H)
  • Acids turn blue litmus paper red.
  • Acids dissolve in water to form solutions which can conduct electricity.
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32
Q

lower pH = __ acids

A

stronger

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33
Q

what are bases

A

alkalis
(all alkalis are bases)

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34
Q

what are some common alkalis (+ chemical formula)

A
  • sodium hydroxide - NaOH (e.g. toothpaste, soap)
  • ammonium hydroxide - NH (e.g. cleaning product, fertiliser)
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35
Q

all alkalis are __ when dissolved in water

A

OH⁻

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36
Q

what pH level is neutral

A

7

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37
Q

higher pH = ___ alkali

A

stronger

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38
Q

what colour does litmus paper turn when it is put in acids

A

red

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39
Q

what colour does litmus paper turn when it is put in alkali

A

blue

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40
Q

what is the definition of universal indicators

A

a pH indicator made of a solution of several compounds that exhibit various smooth colour changes over a wide range pH values to indicate the acidity or alkalinity of solutions.

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41
Q

how to read pH scale

A
  • strong acids → weak acids → neutrals → weak alkalis → strong alkalis
  • red to light green = acid
  • dark green to purple = alkali
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42
Q

what does pH paper tell us

A
  • determines if the substance is acidic or alkaline and the numerical pH value
  • therefore, gives a more precise reading (exact pH value) than litmus paper
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43
Q

what does litmus paper tell us

A
  • determines only if the substance is acidic or alkaline
  • blue litmus paper turns red in acids, red litmus paper turns blue in alkalis
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44
Q

what is the formulae to find ionic compounds

A

cross multiply

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45
Q

what is chemical equations

A

A chemical equation shows what happens in a chemical reaction

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46
Q

how is the chemical formulae of ionic compounds formed

A
  • by balancing the charges on the positive and negative ions.
  • all the positive charges must equal all the negative charges in an ionic compound.
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47
Q

what can chemical equations tell us

A
  • which reactants and products are involved in the reaction
  • the relative amounts of reactants and products
  • the physical states of the reactants and products of the reaction.
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48
Q

what is a balanced chemical equation

A

must contain equal numbers of atoms of each element on both sides of the equation.

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49
Q

what is on the left side of a chemical equation

A

The reactant(s)

e.g. 2H₂(g) + O₂(g) → 2H₂O(l)

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50
Q

what is on the right side of a chemical reaction

A

The product(s)

e.g. 2H₂(g) + O₂(g) → 2H₂O(l)

51
Q

what are the state symbols

A

(s) – solid
(g) – gas
(l) – liquid
(aq) – aqueous solution (dissolved in water)

52
Q

how to make chemical equation balanced

A
  1. Write down the chemical formulae of the reactants and products to get the chemical equation.
  2. Check the number of atoms of each element in the formulae on both sides of the equation.
    if the equation is not balanced:
  3. Add the state symbols to indicate the physical state of each reactant and product.
53
Q

how to meassure the pH of given substance

A
  • Chemical compound called an indicator
  • pH sensor attached to a data logger
  • pH meter
54
Q

application of pH scale

A

pH of Soil:
- Most plants grow best in neutral or slightly acidic soils.
- It is important to control the pH of soil because it will affect the growth and development of plants.

55
Q

related to soil too

another application of pH scale

A

Controlling pH of Soil:
pH of soil may become unsuitable for plant growth due to:
* too much fertilisers added to the soil
* environmental pollution such as acid rain.

To treat acidity in soil, add:
* calcium oxide (quicklime)
* calcium hydroxide (slaked lime)

56
Q

what is the general equation for acid and alkali

A

acid + alkali = salt + water

57
Q

what is the general equation for acids + metal carbonate

A

acids + metal carbonate = salt + water + carbon dioxide

58
Q

what is the chemical formula for water

A

H₂0

59
Q

what is the general equation for acids + metal

A

acids + metal = salt + hydrogen

60
Q

what is the chemical formula for hydrogen gas

A

H₂

61
Q

what is the chemical formula for carbon dioxide

A

CO₂

62
Q

what is the chemical formula for oxygen gas

A

0₂

63
Q

what is the chemical formula for chlorine gas

A

Cl₂

64
Q

what do you do when you want to find out whether hydrogen gas is present

A
  • carry out the experiment(e.g. acid +metal)
  • place a lighted splint near the solution
  • if the lighted splint extinguishes with a pop sound, hydrogen is present
65
Q

what do you do when you want to find out whether carbon dioxide is present

A
  • carry out the experiment(e.g. acid+ carbonate)
  • bubble the gas into limewater/calcium hydroxide)
  • if white precipitate forms in limewater, carbon dioxide is present (effervesence)
66
Q

what is the chemical formula for sulfate ION

A

SO₄²⁻

67
Q

what is the chemical formula for ammonium ION

A

NH₄⁺

68
Q

what is the chemical formula for hydorxide ION

A

OH⁻

69
Q

what is the chemical formula for nitrate ION

A

NO₃⁻

70
Q

what is the chemical formula for carbonate ION

A

CO₃²⁻

71
Q

what is the chemical formula for chloride ION

A

Cl⁻

72
Q

what is the chemical formula for sodium ION

A

Na⁺

73
Q

what is the chemical formula for potassium ION

A

K⁺

74
Q

what is the chemical formula for magnesium ION

A

Ma²⁺

75
Q

what is the chemical formula for calcium ION

A

Ca²⁺

76
Q

what is the chemical formula for copper(II) ION

A

Cu²⁺

77
Q

what is the chemical formula for iron(II) ION

A

Fe²⁺

78
Q

what is the chemical formula for iron(III) ION

A

Fe³⁺

79
Q

what is the chemical formula for silver ION

A

Ag⁺

80
Q

what is the chemical formula for zinc ION

A

Zn²⁺

81
Q

what is the chemical formula for aluminum ION

A

Al³⁺

82
Q

what is the chemicla formula for calcium and carbonate

A

CaCO₃

83
Q

what is the chemical formula for calcium and nitric

A

Ca(NO₃)₂

84
Q

what is the chemical formula for calcium and sulfric

A

CaSO₄

85
Q

what is the chemical formual for calcium and chloride

A

CaCl₂

86
Q

what is the chemical formula for magnesium and chloride

A

MgCl₂

87
Q

what is the chemical formula for magnesium and sulfric

A

MgSO₃

88
Q

what is the chemical formula for magnesium and carbonate

A

MgCO₃

89
Q

what is the chemical formula fro magnesium and nitrate

A

Mg(NO₃)₂

90
Q

what is the chemical formula for potassium and chloride

A

KCl

91
Q

what is the chemical formula for potassium and sulfric

A

K₂SO₄

92
Q

what is the chemical formula for potassium and carbonate

A

K₂CO₃

93
Q

what is the chemical formula for potassium and nitrate

A

KNO₃

94
Q

what is the chemical formula for sodium and chloride

A

NaCl

95
Q

what is the chemical formula for sodium and sulfric

A

Na₂SO₄

96
Q

what is the chemical formula for sodium and carbonate

A

Na₂CO₃

97
Q

what is the chemical formula for sodium and nitrate

A

NaNO₃

98
Q

what is the chemical formula for copper(II) and chloride

A

CuCl₂

99
Q

what is the chemical formula for copper(II) and sulfric

A

CuSO₄

100
Q

what is the chemical formula for copper(II) and carbonate

A

CuCO₃

101
Q

what is the chemical formula fro copper(II) and nitrate

A

Cu(NO₃)₂

102
Q

what is the chemical formula for zinc and chloride

A

ZnCl₂

103
Q

what is the chemical formula for zinc and nitrate

A

Zn(NO₃)₂

103
Q

what is the chemical formula for zinc and sulfric

A

ZnSO₄

104
Q

what is the chemical formula for zinc and carbonate

A

ZnCO₃

105
Q

what is the chemical formula for aluminium and sulfric

A

Al₂(SO₄)₃

106
Q

what is the chemical formula for aluminium and nitrate

A

Al(NO₃)₃

106
Q

what is the chemical formula for aluminium and carbonate

A

Al₂(CO₃)₃

106
Q

what is the chemical formula for aluminium and chloride

A

AlCl₃

107
Q

what are some examples of acidic substance at pH level 1

A

battery acid

108
Q

what is an examples of a substance at pH level 2

A

lemon juice

109
Q

what is an example of a substance at pH level 3

A

vinegar

110
Q

what is an example of a substance at pH level 4

A

tomato juice

111
Q

what is an example of a substance at pH level 5

A

coffee

112
Q

what is an example of a substance at pH level 6

A

milk

113
Q

what is an example of a substance at pH level 7

A

pure water

114
Q

what is an example of a substance at pH level 8

A

sea water/eggs

115
Q

what is an example of a suubstance at pH level 9

A

baking soda

116
Q

what is an example of a substance at pH level 10

A

milk of magnesia

117
Q

what is an example of a substance at pH level 11

A

ammonia solution

118
Q

what is an example of a substance at pH level 12

A

soapy water

119
Q

what is an example of a substance at pH level 13

A

bleach

120
Q

what is an example of a substance at pH level 14

A

liquid drain cleaner

121
Q

when do you add bracket

A

when an ion is made up of multiple atoms (poly atomic)

take it as one whole thing

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