U1- Stoichiometry, Gravimetric Analysis and Gases

Question 1

limiting reactant

Answer 1

reactant that is completely consumed in reaction

Question 2

gravimetric analysis

Answer 2

technique which the amount of an analyte can be determined through the measurement of mass before and/or after a physical or chemical change

Question 3

precipitate

Answer 3

A solid that is formed in a reaction between two dissolved substances or gases​

Question 4

analyte

Answer 4

The ion or solution being analysed​

Question 5

residue

Answer 5

The solid remaining in the filter paper during filtration​

Question 6

filtrate

Answer 6

The liquid that passes through the filter paper during filtration​

Question 7

dry to constant mass

Answer 7

A process in which a solid is weighed, dried and re-weighed until the mass no longer changes. This ensures that all of the excess water has been completely removed.​

Question 8

validity

Answer 8

whether evidence supports the argument

Question 9

sources of error in a gravimetric analysis (6)

Answer 9

solubility (or insolubility) of precipitate
variation of solubility w temp
losses through splashes, inefficient rinsing and inefficient filtering
extend of drying of solid
is all of the active ingredient precipitated out? (solved by adding excess reagent)
measurement errors

Question 10

how could solubility of precipitate of gravimetric analysis impact results

Answer 10

incomplete precipitation –> lower experimental content then expected –> decreased measurement mass

Question 11

how could variation in solubility with temperature impact gravimetric analysis results

Answer 11

incomplete precipitation –> lower experimental content then expected –> decreased measurement mass

Question 12

how could losses thru splashing, inefficient rinsing and inefficient filtering impact gravimetric analysis results

Answer 12

incomplete transfer of precipitate –> lower exp content than expected –> decreased measured mass

Question 13

how could the extent of drying the solid impact gravimetric results

Answer 13

water in precipitate –> higher experimental content than expected –> increased measured mass

Question 14

how could not all the active ingredient not being precipitated out impact results of the gravimetric analysis

Answer 14

incomplete precipitate –> lower exp content than expected

Question 14

how could not all the active ingredient not being precipitated out impact results of the gravimetric analysis

Answer 14

incomplete precipitate –> lower exp content than expected

Question 15

how could measurement errors impact gravimetric analysis results

Answer 15

random outcome due to inaccuracies w measurements of mass, volume ect

Question 16

properties of ideal gases

Answer 16

constant and random motion,
very far apart
negligible attractive or repulsive forces bw particles
collisions bw particles are perfectly elastic (X loss of k nrg)

Question 17

pressure conversions:

kPa to mmHg to atm

Answer 17

100kPa = 750mmHg = 0.987atm

Question 18

Boyle’s Law

Answer 18

for a fixed amount of gas at constant temperature, pressure is inversely proportional to volume.
P1V1 = P2V2

Question 19

Charles Law

Answer 19

For a given amount of gas at constant pressure, volume is directly proportional to the absolute temperature
V1/T1 = V2/T2

Question 20

standard temperature and pressure (STP)

Answer 20

0C / 273K

100kPa

Question 21

standard lab conditions (SLC)

Answer 21

25C / 298K
100kPa
molar gas v= 22.7L/mol

Question 22

molar gas volume

Answer 22

equal volumes of all gases measured at the same temperature and pressure contain the same number of particles

Question 23

why does the solution (silver nitrate) you mix with the analyte need to be in excess
eg Ag+(aq)+ Cl-(aq)> AgCl(s), add Silver Nitrate in excess to mineral water being analysed.(analysis of chloride ions)

Answer 23

so that there are more than enough silver ions to precipitate all of the ions out of the solutions

Question 24

atom economy

Answer 24

Mr of desired products/ Mr of total products x100

Question 25

% yield

Answer 25

actual yield/ theoretical yield x100