Page 1 of 43
UBC CHEM 123 LAB 2026 FINAL EXAM
COMPLETE (174) CURRENT TESTING
QUESTIONS AND DETAILED CORRECT
ANSWERS|GUARANTEED PASS.
UBC
Ace your preparation with this UBC CHEM 123 Lab Final Exam,
designed to assess foundational skills in general chemistry
laboratory practice. It focuses on experimental techniques, data
analysis, lab safety, and interpretation of results. The exam
strengthens understanding of core chemistry concepts through
practical application. Suitable for chemistry students preparing
for lab finals and coursework assessments.
why do we perform iodometric titrations ✓ ✓ ...... 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? ✓
✓ ...... ANSWER ....... combine solutions, reach endpoint,
calculate, determine the concentration of the unknown
, Page 2 of 43
What reaction takes place during an iodometric titration? ✓
✓ ...... ANSWER ....... oxidation-reduction reaction
what is used as the oxidizing agent in an iodometric titration?
✓ ✓ ...... ANSWER ....... potassium iodate
top-loading balance ✓ ✓ ...... ANSWER ....... - used for
prepwork and obtains a mass to the nearest +/-0.1g
(uncertainty of +/- 0.05g)
- used prior to analytical balance
analytical balance ✓ ✓ ...... 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? ✓ ✓ ...... ANSWER .......
analytical balance
when is a reading considered stable? ✓ ✓ ...... ANSWER
....... if it persists for 2 seconds
, Page 3 of 43
what temperature should objects be weighed? ✓ ✓ ......
ANSWER ....... at room temperature
should objects be dry or wet when weighed? ✓ ✓ ......
ANSWER ....... Dry
should you use the same balance for all measurements? ✓
✓ ...... ANSWER ....... yes
Describe the steps for weighing by difference ✓ ✓ ......
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)
, Page 4 of 43
Subtract value 2 from value 1 to get the mass of the
chemical
how do we know if something is a standard solution? ✓ ✓
...... 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) ✓ ✓ ...... 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)
- fill volumetric flask to a few centimetres below the
calibration mark (do not go above this line)
- use a dropper to add water dropwise to volumetric flask
until the bottom of the meniscus is resting on the calibration
line (if you go past calibration mark, you must start over)
- stopper the flask and invert the flask 20x
UBC CHEM 123 LAB 2026 FINAL EXAM
COMPLETE (174) CURRENT TESTING
QUESTIONS AND DETAILED CORRECT
ANSWERS|GUARANTEED PASS.
UBC
Ace your preparation with this UBC CHEM 123 Lab Final Exam,
designed to assess foundational skills in general chemistry
laboratory practice. It focuses on experimental techniques, data
analysis, lab safety, and interpretation of results. The exam
strengthens understanding of core chemistry concepts through
practical application. Suitable for chemistry students preparing
for lab finals and coursework assessments.
why do we perform iodometric titrations ✓ ✓ ...... 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? ✓
✓ ...... ANSWER ....... combine solutions, reach endpoint,
calculate, determine the concentration of the unknown
, Page 2 of 43
What reaction takes place during an iodometric titration? ✓
✓ ...... ANSWER ....... oxidation-reduction reaction
what is used as the oxidizing agent in an iodometric titration?
✓ ✓ ...... ANSWER ....... potassium iodate
top-loading balance ✓ ✓ ...... ANSWER ....... - used for
prepwork and obtains a mass to the nearest +/-0.1g
(uncertainty of +/- 0.05g)
- used prior to analytical balance
analytical balance ✓ ✓ ...... 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? ✓ ✓ ...... ANSWER .......
analytical balance
when is a reading considered stable? ✓ ✓ ...... ANSWER
....... if it persists for 2 seconds
, Page 3 of 43
what temperature should objects be weighed? ✓ ✓ ......
ANSWER ....... at room temperature
should objects be dry or wet when weighed? ✓ ✓ ......
ANSWER ....... Dry
should you use the same balance for all measurements? ✓
✓ ...... ANSWER ....... yes
Describe the steps for weighing by difference ✓ ✓ ......
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)
, Page 4 of 43
Subtract value 2 from value 1 to get the mass of the
chemical
how do we know if something is a standard solution? ✓ ✓
...... 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) ✓ ✓ ...... 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)
- fill volumetric flask to a few centimetres below the
calibration mark (do not go above this line)
- use a dropper to add water dropwise to volumetric flask
until the bottom of the meniscus is resting on the calibration
line (if you go past calibration mark, you must start over)
- stopper the flask and invert the flask 20x
