Chem 280 Final Questions with 100% complete
Solutions Passed (GRADED A+)
What is the difference between external standard method, standard
addition method and internal standard method? - VERIFIED ANSWER -
External Standard Method: Unknown samples have similar composition
and the matrix is known. Have to have to 5 samples but not all have to
have high matrix.
Standard Addition Method: Used for more complex and unknown matrices
for 1 unknown sample. Internal Standard Method: used when don't need
volume and measure using matrix composition
The standard addition method is not the best method when the sample
matrix can interfere with the analyte's signal. - VERIFIED ANSWER - True
The y-intercept is used determine the concentration of an unknown
compound for the standard addition method. - VERIFIED ANSWER - False
What is the difference between internal standard method and external
standard method? SKIP - VERIFIED ANSWER - SKIP
,The internal standard method requires the exact volume of peeps solution
to be known. - VERIFIED ANSWER - False
An ideal internal standard will have a minimum absorbance at the
analyte's maximum absorbance. - VERIFIED ANSWER - True
The same cuvette used to blank the spectrophotometer should be used
for all subsequent absorbance measurements and not a different cuvette.
- VERIFIED ANSWER - False
Sodium Carbonate is a Primary Standard - VERIFIED ANSWER - True
Na2CO3 will react with 2 equivalents for HCL - VERIFIED ANSWER - True
For the greatest accuracy at the beginning of each titration, the initial
volume of the titrant in the buret must be exactly 0.00mL - VERIFIED
ANSWER - False
,The volume of the solution being titrated does not matter, only the mole of
analyte, which is calculated from the mass of analyte added to that
solution. - VERIFIED ANSWER - True
You have reached the colorimetric endpoint of your titration when it
changes colors. - VERIFIED ANSWER - True
How to find %RSD? - VERIFIED ANSWER - SD/ mean * 100 (want < 5%)
When using a volumetric pipet, to assure complete transfer of all liquid, a
suction bulb should be used to blow out any remaining liquid in tip of pipet.
- VERIFIED ANSWER - False
If you forgot to rinse your volumetric pipet with the standardized solution
before pipetting, the actual concentration will lower than what is labeled
on the reagent bottle. - VERIFIED ANSWER - True
A volumetric flask volume should be recorded to 4 sig figs (2 digits after
decimal) - VERIFIED ANSWER - True
The acetic acid is the analyte in the experiment - VERIFIED ANSWER - True
, A micropipette's volume is 'To contain' or TC so all liquid is ejected from
the tip - VERIFIED ANSWER - True
A 1st derivative will be taken of the titration data such that the exact point
of infection is determined - VERIFIED ANSWER - True
2 moles of NaOH will be needed to react with 1 mole of tartaric acid -
VERIFIED ANSWER - True
If an object absorbs blue light, it will appear red. - VERIFIED ANSWER -
False
Tartaric acid absorbs light strongly at 520 nm. - VERIFIED ANSWER - False
When are potentiometric titrations important? - VERIFIED ANSWER - They
are the best when the sample being titrated is colored.
Beer's law tells us that the amount of light absorbed is directly
proportional to the concentration of the absorbing species (or analyte) -
VERIFIED ANSWER - True
Solutions Passed (GRADED A+)
What is the difference between external standard method, standard
addition method and internal standard method? - VERIFIED ANSWER -
External Standard Method: Unknown samples have similar composition
and the matrix is known. Have to have to 5 samples but not all have to
have high matrix.
Standard Addition Method: Used for more complex and unknown matrices
for 1 unknown sample. Internal Standard Method: used when don't need
volume and measure using matrix composition
The standard addition method is not the best method when the sample
matrix can interfere with the analyte's signal. - VERIFIED ANSWER - True
The y-intercept is used determine the concentration of an unknown
compound for the standard addition method. - VERIFIED ANSWER - False
What is the difference between internal standard method and external
standard method? SKIP - VERIFIED ANSWER - SKIP
,The internal standard method requires the exact volume of peeps solution
to be known. - VERIFIED ANSWER - False
An ideal internal standard will have a minimum absorbance at the
analyte's maximum absorbance. - VERIFIED ANSWER - True
The same cuvette used to blank the spectrophotometer should be used
for all subsequent absorbance measurements and not a different cuvette.
- VERIFIED ANSWER - False
Sodium Carbonate is a Primary Standard - VERIFIED ANSWER - True
Na2CO3 will react with 2 equivalents for HCL - VERIFIED ANSWER - True
For the greatest accuracy at the beginning of each titration, the initial
volume of the titrant in the buret must be exactly 0.00mL - VERIFIED
ANSWER - False
,The volume of the solution being titrated does not matter, only the mole of
analyte, which is calculated from the mass of analyte added to that
solution. - VERIFIED ANSWER - True
You have reached the colorimetric endpoint of your titration when it
changes colors. - VERIFIED ANSWER - True
How to find %RSD? - VERIFIED ANSWER - SD/ mean * 100 (want < 5%)
When using a volumetric pipet, to assure complete transfer of all liquid, a
suction bulb should be used to blow out any remaining liquid in tip of pipet.
- VERIFIED ANSWER - False
If you forgot to rinse your volumetric pipet with the standardized solution
before pipetting, the actual concentration will lower than what is labeled
on the reagent bottle. - VERIFIED ANSWER - True
A volumetric flask volume should be recorded to 4 sig figs (2 digits after
decimal) - VERIFIED ANSWER - True
The acetic acid is the analyte in the experiment - VERIFIED ANSWER - True
, A micropipette's volume is 'To contain' or TC so all liquid is ejected from
the tip - VERIFIED ANSWER - True
A 1st derivative will be taken of the titration data such that the exact point
of infection is determined - VERIFIED ANSWER - True
2 moles of NaOH will be needed to react with 1 mole of tartaric acid -
VERIFIED ANSWER - True
If an object absorbs blue light, it will appear red. - VERIFIED ANSWER -
False
Tartaric acid absorbs light strongly at 520 nm. - VERIFIED ANSWER - False
When are potentiometric titrations important? - VERIFIED ANSWER - They
are the best when the sample being titrated is colored.
Beer's law tells us that the amount of light absorbed is directly
proportional to the concentration of the absorbing species (or analyte) -
VERIFIED ANSWER - True
