sources of errors Flashcards
*impurities present in glassware react with B
LARGER volume of B is required
*impurities present in glassware react with P
SMALLER volume of B is required
burette was not rinsed with B and only rinsed rinsed w water
LARGER volume of B is required
–> B is diluted (lower concentration)
pipette was not rinsed with P and only rinsed with water
SMALLER volume of B is required
–> P is diluted (lower concentration)
–> since volume of P transferred into conical flask remains at 25.0cm^3, no. of moles of P transferred is less
burette was rinsed w P instead of B
LARGER volume of B is required
–> P used to rinse burette will react with B that was used to fill the burette
–> B is diluted
pipette was rinsed with B instead of P
SMALLER volume of B is required
–> B used to rinse pipette will react with P that was used to fill the pipette
–> P is diluted
–> since volume of P transferred into conical flask remains at 25.0cm^3, no. of moles of P transferred is less
conical flask rinsed w P
LARGER volume of B is required
–> more P is present in the conical flask
–> more B is needed to react with the additional P
conical flask was rinsed with B
SMALLER volume of B is required
–> less B from burette is required to react with P
parallax error
- reading burette from above eye level when reading initial reading of burette; or
- reading burette from below eye level when reading final reading of burette
LARGER volume of B is calculated
–> initial reading of B will decrease (initial reading of B was recorded lower in magnitude as compared to actual reading) / final reading or B will increase (final reading of B was recorded higher in magnitude as compared to actual reading)
–> (final reading - initial reading) will increase
parallax error
- reading burette from below eye level when reading initial reading of burette; or
- reading burette from above eye level when reading final reading of burette
SMALLER volume of B is calculated
–> initial reading of B will increase (initial reading of B was recorded higher in magnitude as compared to actual reading) / final reading of B will decrease (final reading of B was recorded lower in magnitude as compared to the actual reading)
–> (final reading - initial reading) will decrease
there was a bubble in the burette that was not removed (assuming it was removed during titration)
LARGER volume of B is calculated
–> final reading recorded will be larger than the actual reading
filter funnel in the burette that was not removed (assuming residual drops of B flowed into burette during titration)
SMALLER volume of B is calculated
–> final reading recorded will be smaller than actual reading
–> (final reading - initial reading) will decrease
volume larger than 25.0cm^3 was used to fill the pipette (possible cause: filling above mark due to parallax error)
LARGER volume of B is required
–> larger volume of P is transferred to conical flask
volume smaller than 25.0cm^3 was used to fill pipette
possible causes: filling below the mark due to parallax error, reading the tip of the meniscus, failed to remove bubble in pipette
SMALLER volume of B is required
–> smaller volume of P is transferred to conical flask
did not add drop-wise when nearing end-point
LARGER volume of B is used
