CHEM 123 LAB FINAL UBC FINAL PAPER 2026
SOLVED QUESTIONS AND FULL SOLUTION
UPDATED
◉ how to clean the burette
Answer: - use clean funnel over the sink & add 5-10mL of deionized
water with the stopcock closed
- hold in horizontal position and roll to coat insides with water
- drain water through tip by opening the stopcock
- repeat 2x
- close stopcock again and use clean funnel & add 5-10mL of solution
into burette
- hold horizontally and coat sides of burette with solution & drain
through stopcock into sink or waste beaker
◉ how to fill the burette
Answer: - close stopcock & use funnel to fill burette to 0 mark &
clamp burette at bench with waste beaker under the tip
- open stopcock to drain some solution to ensure the burette has no
air bubbles (not essential to fill exactly to 0.00)
- fill the burette, remove funnel, touch tip of burette to inside wall of
a beaker to remove any drops on the tip
,◉ How to read the burette
Answer: - read at lowest point of meniscus (make sure eyes are
parallel)
- use white card/paper behind the burette below meniscus to see
- record meniscus/volume of burette to 2 decimal places
◉ how to Operate the burette
Answer: - record initial volume of burette to 2 decimal places
- lower burette tip into erlenmeyer flask that has the solution to be
titrated
- open stopcock slowly with left hand & adjust flow rate by using
thumb & 2 fingers around the stopcock
- turn on magnetic stirrer to low speed (avoids solution splashing up
walls of the flask
- wait about 30 seconds & record final volume of the burette to 2
decimal places
◉ precision
Answer: how close measured values are to each other
◉ accuracy
Answer: how close a measured value is to the true value
, ◉ what does more significant figures mean?
Answer: means that the measurement is more precise
◉ what significant figures are certain and which are uncertain?
Answer: all digits but the last one are certain
the last digit is uncertain
◉ what is the general rule for volumetric analysis and sig figs?
Answer: measurements need to be precise to at least 4 sig figs (make
sure to maintain this precision level when transferring from
container to container)
◉ rule for sig figs in titration results
Answer: when adding or subtracting measurements, result is
expressed to the 1st uncertain decimal place (determines the
number of sig numbers in the answer)
◉ rule for sig figs multiplication
Answer: product will have the same number of sig figs as the
multipler or divisor w/the smallest number of sig figs
SOLVED QUESTIONS AND FULL SOLUTION
UPDATED
◉ how to clean the burette
Answer: - use clean funnel over the sink & add 5-10mL of deionized
water with the stopcock closed
- hold in horizontal position and roll to coat insides with water
- drain water through tip by opening the stopcock
- repeat 2x
- close stopcock again and use clean funnel & add 5-10mL of solution
into burette
- hold horizontally and coat sides of burette with solution & drain
through stopcock into sink or waste beaker
◉ how to fill the burette
Answer: - close stopcock & use funnel to fill burette to 0 mark &
clamp burette at bench with waste beaker under the tip
- open stopcock to drain some solution to ensure the burette has no
air bubbles (not essential to fill exactly to 0.00)
- fill the burette, remove funnel, touch tip of burette to inside wall of
a beaker to remove any drops on the tip
,◉ How to read the burette
Answer: - read at lowest point of meniscus (make sure eyes are
parallel)
- use white card/paper behind the burette below meniscus to see
- record meniscus/volume of burette to 2 decimal places
◉ how to Operate the burette
Answer: - record initial volume of burette to 2 decimal places
- lower burette tip into erlenmeyer flask that has the solution to be
titrated
- open stopcock slowly with left hand & adjust flow rate by using
thumb & 2 fingers around the stopcock
- turn on magnetic stirrer to low speed (avoids solution splashing up
walls of the flask
- wait about 30 seconds & record final volume of the burette to 2
decimal places
◉ precision
Answer: how close measured values are to each other
◉ accuracy
Answer: how close a measured value is to the true value
, ◉ what does more significant figures mean?
Answer: means that the measurement is more precise
◉ what significant figures are certain and which are uncertain?
Answer: all digits but the last one are certain
the last digit is uncertain
◉ what is the general rule for volumetric analysis and sig figs?
Answer: measurements need to be precise to at least 4 sig figs (make
sure to maintain this precision level when transferring from
container to container)
◉ rule for sig figs in titration results
Answer: when adding or subtracting measurements, result is
expressed to the 1st uncertain decimal place (determines the
number of sig numbers in the answer)
◉ rule for sig figs multiplication
Answer: product will have the same number of sig figs as the
multipler or divisor w/the smallest number of sig figs
