Volumetric Analysis Flashcards

1
Q

What is a Volumetric Analysis?

A

Quantitative Technique
Involves measuring volume of a solution with a known concentration which is used to determine the concentration of the analyte.

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2
Q

What process is involved in a volumetric analysis?

A

Titration

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3
Q

Steps to a Volumetric Analysis

A
  1. Preparation of standard solution
  2. Titration between standard solution and solution to be standardised
  3. Titration between standardised solution and analyte
  4. Calculations to determine analyte concentration
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4
Q

Volumetric Flask

A

Used to prepare standard solution
A fixed volume usually 100mL or 250mL

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5
Q

Pipette

A

Used to transfer a known volume of solution being analyzed to the conical flask
Fixed volume, commonly 20 - 25mL

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6
Q

Aliquot

A

an amount taken from a larger quantity, so that it can be tested

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7
Q

Burette

A

A variable volume
Holds up to 50mL
Contains the standard solution

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8
Q

Titre

A

the volume of a solution required to complete a reaction in a titration.

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9
Q

Conical Flask

A

Used for holding the aliquot delivered by the pipette

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10
Q

What is a standard solution?

A

Concentration is accurately known, prepared in volumetric flask, prepared using a primary standard

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11
Q

Requirements of a primary standard

A
  • available in pure form
  • known formula
  • stable enough to not react with the atmosphere
  • soluble in water
  • high molar mass
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12
Q

Standardization

A

A standard solution can be used to standardise another solution

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13
Q

Titration

A

adding one solution to another until a reaction is complete

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14
Q

Indicator

A

signals the point where neutralisation reaction is complete

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15
Q

Equivalence point

A

reaction is complete according to mole ratios in equation

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16
Q

Endpoint

A

when the indicator changes colour

17
Q

Factors to consider when choosing an indicator

A

End point of the indicator must be close to the equivalence point of the reaction

18
Q

What does CONCORDANT mean?

A

0.10mL between the lowest and highest titre

19
Q

Why should we use concordant titres?

A

Increases reliability and precision of results, minimizing effects of random errors

20
Q

STRONG ACIDS

A

HCl, NO3, H2SO4

21
Q

WEAK ACIDS

A

Carboxylic acids

22
Q

STRONG BASES

A

NaOH, KOH, Ba(OH)2

23
Q

WEAK BASES

A

NH3

24
Q

What are TITRATION CURVES?

A

Graph of Burette Volume versus pH in the titration flask

25
Q

What are the types of experimental errors in a volumetric analysis?

A
  1. Rinsing Errors
  2. Indicator Errors
26
Q

What are rinsing errors?

A

Lead to either overestimations or underestimations of analyte concentration
Effects size of the titre delivered

27
Q

What should the volumetric flask be rinsed with?

A

Distilled Water

28
Q

What should the pipette be rinsed with?

A

The solution it is to contain

29
Q

Why shouldn’t we rinse the pipette with water?

A
  • decrease the concentration of solution in the pipette
  • hence a smaller titre of would be delivered by the burette to react completely
  • leading to a lower calculated concentration (underestimation)
30
Q

Why shouldn’t we rinse the pipette with a more concentrated solution?

A
  • Increase the concentration of solution in the pipette
  • Larger titre required to react completely
  • Higher calculated concentration (overestimation)
31
Q

What should the burette be rinsed with?

A

With the solution it is to contain

32
Q

Why shouldn’t the burette be rinsed with water?

A
  • dilute the concentration of solution in burette
  • larger titre required to react completely
  • higher calculated concentration of analyte
33
Q

Why shouldn’t the burette be rinsed with a more concentrated solution?

A
  • increase the concentration of solution in the burette
  • smaller titre required to react completely
  • lower calculated concentration of analyte
34
Q

What should the conical flask be rinsed with?

A

Distilled water

35
Q

Why shouldn’t you rinse the conical flask with the solution it is to contain?

A
  • Increases the concentration of solution
  • Greater titre required
  • Overestimation
36
Q

Poor Indicator Choice

A

Incorrect indicator choice can lead to overestimations and underestimations of final concentration

37
Q

Missed Indicator Endpoint

A

If titration is stopped after endpoint, the size of the titre will be bigger than it should be