Chapter 4 - The Mole & Volumetric Analysis Flashcards

1
Q

What is relative atomic mass (of an element)?

A

The average mass of one atom of the element relative to 1/12 of the mass of a carbon-12 atom

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2
Q

What is the symbol for relative atomic mass?

A

Ar

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3
Q

What is the unit for relative atomic mass?

A

no unit

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4
Q

The relative atomic mass of an element takes into account the mass of all the ________ of the element and their ________

A

isotopes

relative abundance

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5
Q

What is relative molecular mass (of a molecule)?

A

The average mass of one molecule of the element or compound relative to 1/12 of the mass of a carbon-12 atom

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6
Q

What is the symbol for relative molecular mass?

A

Mr

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7
Q

What is the unit for relative molecular mass?

A

no unit

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8
Q

What is relative formula mass (of an ionic compound)?

A

The average mass of one unit of the ionic compound relative to 1/12 of the mass of a carbon-12 atom

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9
Q

What is the symbol for relative formula mass?

A

Mr

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10
Q

What is the unit for relative formula mass?

A

no unit

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11
Q

What is molar mass (of an element)?

A

The mass of one mole of atoms of the element

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12
Q

What is the unit for molar mass?

A

g/mol

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13
Q

The molar mass of an element is equal to its ________ in grams

A

relative atomic mass (Ar)

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14
Q

The molar mass of a molecule is equal to its ________ in grams

A

relative molecular mass (Mr)

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15
Q

The molar mass of an ionic compound is equal to its ________ in grams

A

relative formula mass (Mr)

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16
Q

Formula to calculate number of moles

A

Number of moles = Number of particles / 6.02 x 10^23

Number of moles = Mass (in g) / Molar mass (in g/mol)

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17
Q

Formula to calculate percentage composition by mass

A

Percentage composition by mass = (Ar of the element x Number of atoms of the element in the formula) / Mr of the compound x 100%

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18
Q

The empirical formula of a compound shows…

A
  1. the types of elements present in the compound

2. the simplest ratio of the different types of atoms in the compound

19
Q

The molecular formula of a compound shows…

A

the exact number of atoms of each element in a molecule of the compound

20
Q

The molecular formula is ________ of the empirical formula

A

always a multiple

21
Q

One mole of any gas occupies a volume of ____ at ________

A

24dm^3

room temperature and pressure

22
Q

24dm^3 is the ________ of a gas at r.t.p.

A

molar volume

23
Q

Equal volumes of gases have ________ number of moles and ________ masses

A

the same

different

24
Q

Formula to calculate number of moles of gas

A

Number of moles of gas = Volume of gas in dm^3 / 24dm^3

25
Q

What is a limiting reagent?

A

The reactant that reacts completely and hence limits the amount of product produced

26
Q

Formula to calculate percentage purity of starting reagent

A

Percentage purity = Pure mass of starting reagent / Total impure mass x 100%

27
Q

Formula to calculate percentage yield of product

A

Percentage yield = Actual yield / Theoretical yield x 100%

28
Q

What are some possible reasons that the actual yield is often less than the theoretical yield of the product in an experiment?

A
  1. Impure starting reagent
  2. Not mixed well
  3. Product not entirely collected
  4. Spills
29
Q

What is a solution?

A

A fluid with dissolved substances in it

30
Q

What is a solute?

A

The dissolved substance in a solution (usually solid)

31
Q

What is a solvent?

A

The fluid in which the solute dissolves (usually liquid)

32
Q

What is a saturated solution?

A

A solution with the maximum amount of solute dissolved in it

33
Q

What are factors affecting how much solute can be dissolved in a solvent?

A
  1. Volume of solvent
  2. Temperature
  3. Solubility of solute
34
Q

What is the concentration of a solution?

A

The amount of solute in 1 dm^3 of a solution

35
Q

What is the unit for concentration of a solution?

A

g/dm^3

mol/dm^3

36
Q

Formula to calculate concentration of a solution

A

Concentration in g/dm^3 = Mass of solute (in g) / Volume of solution (in dm^3)
Concentration in mol/dm^3 = Number of moles of solution / Volume of solution (in dm^3)

37
Q

Formula to calculate concentration of a solution in mol/dm^3 from its concentration in g/dm^3

A

Concentration in mol/dm^3 = Concentration in g/dm^3 / Molar mass of solute

38
Q

What is titration?

A

A laboratory technique in which a fixed volume of an unknown solution is reacted with a fixed volume and concentration of a known solution

39
Q

What is the function of titration?

A

To accurately determine the concentration of an unknown solution

40
Q

What are the apparatus used to measure accurate volumes?

A
  • Pipette (for a solution of fixed volume)

- Burette (for a solution that is added gradually)

41
Q

What is a titrant?

A

A solution of known concentration

usually filled in the burette

42
Q

What is an analyte?

A

A solution of unknown concentration (that can be experimentally determined)
(usually pipetted into the conical flask)

43
Q

Why is there a need for a suitable pH indicator in an acid-base titration?

A
  • Starting solutions are colourless (unable to tell whether reaction has occurred)
  • Precipitate is soluble (no indication that reaction has occurred)