1
Chem 123 Lab Final UBC 2026-
Comprehensive Q&A For Certification
Success
why do we perform iodometric titrations - correct-answer -to find the
concentration of an unknown by mixing it with a solution of known concentration
What are the 4 (general) steps of an iodometric titration? - correct-answer -
combine solutions, reach endpoint, calculate, determine the concentration of the
unknown
What reaction takes place during an iodometric titration? - correct-answer -
oxidation-reduction reaction
what is used as the oxidizing agent in an iodometric titration? - correct-answer -
potassium iodate
,2
top-loading balance - correct-answer -- used for prepwork and obtains a mass to
the nearest +/-0.1g (uncertainty of +/- 0.05g)
- used prior to analytical balance
analytical balance - correct-answer -- used to determine a precise mass to the
nearest +/- 0.0001 g
- masses are always reported to 4 decimal places
does an analytical balance or top-loading balance need to be recorded to 4
decimal places? - correct-answer -analytical balance
when is a reading considered stable? - correct-answer -if it persists for 2 seconds
what temperature should objects be weighed? - correct-answer -at room
temperature
should objects be dry or wet when weighed? - correct-answer -Dry
, 3
should you use the same balance for all measurements? - correct-answer -yes
Describe the steps for weighing by difference - correct-answer -- place clean
empty weigh boat on top loading balance
- tare top loading balance & weigh boat to 0.00g
- add approximate mass (+/- 20%) of chemical to weigh boat
- close all doors on analytical balance and tare it to 0.0000g
- weigh the sample & weigh boat and record the value (1)
- transfer weighed sample into beaker (from weigh boat)
- weigh the emptied weigh boat and record the value (2)
Subtract value 2 from value 1 to get the mass of the chemical
how do we know if something is a standard solution? - correct-answer -if it has a
known concentration to at least 4 significant figures)
describe the steps to take when preparing a standard solution (in a volumetric
flask) - correct-answer -- weigh & dissolve the solid compound (using weigh by
difference)
- clean the volumetric flask, funnel, and stopper 3x with deionized water
- quantitatively transfer the dissolved sample into the volumetric flask (using and
funnel and rinsing beaker/stir rod with deionized water)
Chem 123 Lab Final UBC 2026-
Comprehensive Q&A For Certification
Success
why do we perform iodometric titrations - correct-answer -to find the
concentration of an unknown by mixing it with a solution of known concentration
What are the 4 (general) steps of an iodometric titration? - correct-answer -
combine solutions, reach endpoint, calculate, determine the concentration of the
unknown
What reaction takes place during an iodometric titration? - correct-answer -
oxidation-reduction reaction
what is used as the oxidizing agent in an iodometric titration? - correct-answer -
potassium iodate
,2
top-loading balance - correct-answer -- used for prepwork and obtains a mass to
the nearest +/-0.1g (uncertainty of +/- 0.05g)
- used prior to analytical balance
analytical balance - correct-answer -- used to determine a precise mass to the
nearest +/- 0.0001 g
- masses are always reported to 4 decimal places
does an analytical balance or top-loading balance need to be recorded to 4
decimal places? - correct-answer -analytical balance
when is a reading considered stable? - correct-answer -if it persists for 2 seconds
what temperature should objects be weighed? - correct-answer -at room
temperature
should objects be dry or wet when weighed? - correct-answer -Dry
, 3
should you use the same balance for all measurements? - correct-answer -yes
Describe the steps for weighing by difference - correct-answer -- place clean
empty weigh boat on top loading balance
- tare top loading balance & weigh boat to 0.00g
- add approximate mass (+/- 20%) of chemical to weigh boat
- close all doors on analytical balance and tare it to 0.0000g
- weigh the sample & weigh boat and record the value (1)
- transfer weighed sample into beaker (from weigh boat)
- weigh the emptied weigh boat and record the value (2)
Subtract value 2 from value 1 to get the mass of the chemical
how do we know if something is a standard solution? - correct-answer -if it has a
known concentration to at least 4 significant figures)
describe the steps to take when preparing a standard solution (in a volumetric
flask) - correct-answer -- weigh & dissolve the solid compound (using weigh by
difference)
- clean the volumetric flask, funnel, and stopper 3x with deionized water
- quantitatively transfer the dissolved sample into the volumetric flask (using and
funnel and rinsing beaker/stir rod with deionized water)
