Unit 3 - Stoichiometry Flashcards

1
Q

Molecular formula

A

The number and type of different atoms in a molecule e.g. CO2

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2
Q

Empirical formula

A

Simplest whole number ratio for different atoms e.g. H2O2 = OH

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3
Q

Valency

A

Number of electrons gained or lost

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4
Q

Valency of all groups

A
  • Group I = 1
  • Group II = 2
  • Group III = 3
  • Group IV = 4
  • Group V = 3
  • Group VI = 2
  • Group VII = 1
  • group VIII = 0
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5
Q

Ionic compound features

A
  • Ions are charged to get full outer shells
  • Compounds final charge must be neutral e.g. k+ + F- = KF
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6
Q

Word equation

A

Chemical names of all reactants and products

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7
Q

Symbol equation

A

Names of substances are replaced by element symbols

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8
Q

Polyatomic ions

A

Ions that have more than one element, e.g. SO4, covalently bonded but unequal protons and electrons

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9
Q

Charges of polyatomic ions

A
  • Hydroxide/OH = 1-
  • Carbonate/CO3 = 2-
  • Chlorate/ClO4 = 1-
  • Nitrate/NO3 = 1-
  • Sulfate/SO4 = 2-
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10
Q

Law of conservation of mass

A

In a reaction the mass of the reactants will equal the mass of the products - mass is conserved

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11
Q

State symbols

A
  • Solid = (s)
  • Liquid = (l)
  • Gas = (g)
  • Aqueous = (aq)
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12
Q

Notation for multiple molecular ions

A

Brackets around ion with amount e.g. Al(NO3)3

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13
Q

Ammonium

A

NH4 = 1+

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14
Q

Ammonia

A

NH3

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15
Q

Relative atomic mass

A

Every atom’s mass is relative to 1/12th of carbon - 12

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16
Q

Symbol for relative atomic mass

A

Ar

17
Q

Relative molecular mass

A

The mass of all atoms in a compound or molecule - can be used for ionic compounds

18
Q

Symbol for relative molecular mass

A

Mr

19
Q

Avogadro’s constant

A

1 mole of a substance has 6.02 x 10^23 atoms in it

20
Q

Relationship with moles and Ar or Mr

A

1 mole of a substance is weighs its Ar or Mr in grams e.g. 1 mole of H20 = 18g

21
Q

Mole, mass and Mr equation

A
  • Mass = Moles x Mr
  • Moles = Mass ÷ Mr
  • Mr = Mass ÷ Moles
22
Q

Molar gas volume law

A

Under same temperature and pressure conditions, equal volumes of different gasses contain an equal number of molecules

23
Q

Molar gas volume constant

A

1 mole of a gas = 24dm^3 = 24000cm^3 = 0.024m^3

24
Q

Room temperature and pressure conditions

A

25˚C and 1 atmospheric pressure

25
Q

moles and gas volume equation

A
  • Moles = Gas volume ÷ 24
  • Gas volume = moles x 24
26
Q

Concentration equation (mass and volume)

A
  • Concentration = Mass ÷ Volume
  • Mass = Concentration x Volume
  • Volume = Mass ÷ Concentration
27
Q

Molar concentration

A

The amount of moles of a substance dissolved in 1dm^3

28
Q

Concentration equation (moles and volume)

A
  • Concentration = Moles ÷ Volume
  • Moles = Concentration x Volume
  • Volume = Moles ÷ Concentration
29
Q

Titrations

A

Used for neutralizing an acid or alkali, can be used to find an unknown volume

30
Q

Limiting reagent

A

The reactant that is completely used in the reaction and controls the amount of product formed

31
Q

Excess reagent

A

The reactant that is left over at the end of the reaction

32
Q

Theoretical yield

A

Moles of product in a balanced equation

33
Q

Actual yield

A

Moles or total mass obtained experimentally

34
Q

Percentage yield

A

Percentage of theoretical yield obtained experimentally

35
Q

Percentage yield equation

A

Percentage yield = (Actual yield ÷ Theoretical yield) x 100

36
Q

Percentage purity of a substance equation

A

Percentage purity = (Mass of pure product ÷ Mass of impure product) x 100

37
Q

Steps to ionic equations

A

1.Identify solids, liquids or gases ( can’t be changed)
2.Identify the ions of the aqueous substances
3.Cross out any ions that appear on both sides of the equation
4.Rewrite the equation without including the species you crossed out

38
Q

Spectator ion

A

An ion that remains unchanged throughout a chemical reaction

39
Q

Steps to finding ratios in a compound

A

1.Find the atomic mass of each element
2.Divide the percentages of the elements in the compound by their masses
3.Divide these numbers by the smallest value to find the ratio