Volumetric analysis

Question 1

what are the two ways to prepare solutions of a base of a required concentration

Answer 1

diluting a more concentrated solution or dissolving a weighed amount of base in a measured volume or water

Question 2

volumetric analysis

Answer 2

a quantitative technique that involves reactions in solution to determine the amount or concentration of a dissolved substance in a solution

Question 3

volumetric analysis is done by

Answer 3

titrations

Question 4

titrations

Answer 4

reactions used to determine the unknown concentration of a solution using a solution with a known concentttration

Question 5

parts of a titrant reaction

Answer 5

analyte, indicator, conical flask, titrant, burette and pipette

Question 6

standard solution

Answer 6

solution with a known concentration

Question 7

how are standard solutions prepared (two ways)

Answer 7

by dissolving a known mass of primary standard in a known measured amount of water or performing a tritration with another standard solution

Question 8

requirements for primary standards

Answer 8

high state of purity, accuratley known chemical formula, easy to store, high molar mass and inexpensive

Question 9

primary standard

Answer 9

substances that are pure so that the emount in moles can be calculated accuratley from there mass

Question 10

what are the steps for making a standard solution

Answer 10

1. weight known mass of substance 2. add substance and water to volumetric flask and swirl until dissolved 4. fill volumetric flask to calibration line

Question 11

why is being able to calculate and compare the number of moles of a solution important in volume-volume stoichiometry

Answer 11

because it allows us to find unknown quantities of reactants used or products made

Question 12

what equipments is used in volumetric analysis

Answer 12

volumetric flask, conical flask, burette and pipette

Question 13

volumetric flask is used

Answer 13

to prepare a standard solution, they come in many difefrent sizes/volumes

Question 14

pipette

Answer 14

used to obtain a known voolume from the standard solution (aliquot)

Question 15

conical flask

Answer 15

contains the analyte and indicator

Question 16

burette

Answer 16

allows the unknown to be added to the known drop by drop

Question 17

pipette is rinsed with

Answer 17

acid/base used

Question 18

burette is rinsed with

Answer 18

acid/based used

Question 19

volumetriic flask is rinsed with

Answer 19

dionised water

Question 20

conical flask is rinsed with

Answer 20

deionised water

Question 21

why are the burette and pipette rinsed with the acid.base

Answer 21

because rinsing with water will dilute the acid/base solution

Question 22

why are the conical and volumetric flasks rinsed with deionised water

Answer 22

because rinsing with an acid or base will introduced unmeasured amounts of acids/bases that into the flask that can react and affect the reuslts

Question 23

what must be achieved to calculate the average of the titrant

Answer 23

concordant titres

Question 24

concodant titres

Answer 24

titres within +-0.1 mLs of eachotehr

Question 25

parallex error

Answer 25

when the volume of liquid in a burette is not measured from the bottom of the meniscus or at eye level

Question 26

titrant

Answer 26

a solution of known concentration to determine the concentration of an unknown substance

Question 27

end point

Answer 27

the point during titration at which the indicator changes colour

Question 28

equivelence point

Answer 28

the point at which the reaction has occured per the stoichiometric ratio of the balanced equation

Question 29

aliquot

Answer 29

a known volume of substance taken from the standard solution using a pipette

Question 30

analyte

Answer 30

a solution of unknown concentration, is added to the burette

Question 31

titre

Answer 31

tthe minimum volume of an unknown solution needed to reach tge end point in titration

Question 32

steps in titrations

Answer 32

1. prepare standard solution 2. obtain aliquot from standard solution using a pipette and added to conical flask 3. add unknown burette and drop until end point is reached

Question 33

steps to calculate unknown using titrattions

Answer 33

1. determine avergae volume of titre 2. use concentration to calculate mols of standard solution 3. use mol ratio to calculate number of mols of unknown 5. calculate concentration of unknown

Question 34

common errors in titrations 7

Answer 34

misreading numbers on scale, using a pipette of incorrect volume, missing endpoint, error in weighing, standard solution not fully dissolved, reading burette scale incorrect, parallex error

Question 35

systematic errors

Answer 35

constant bias in a meaurement that cannot be eliminated by repeeating the measurement

Question 36

stoichiometry

Answer 36

the study of mole ratios, based on the law of conservation of mass

Question 37

what are the two reasons solutions are diluted before carrying out a solution

Answer 37

to achieve titrations that are within the volume range of the burette or the analyte is highly concentration

Question 38

to calculate dilution factor

Answer 38

volume of diluted solution/volume of original solution

Question 39

to find tthe concetration of the diluted solution….

Answer 39

multiply the original concentration by the dilution factor