EXAM 1: CHEM 210 LAB, 2024/2025
WITH CORRECT/ACCURATE ANSWERS
Calculate the absorbance (A) of a sample
from measured transmission data (%T) for
that sample
Beer's Law
Absorbance = Negative Log Base 10 of Transmittance
Make a spectrophotometer calibration curve
(with knowns) and use it to find an
unknown's concentration
1.) Prepare a series of standards with known concentrations of the substance of
interest.
2.) Measure the absorbance of each standard in the spectrophotometer.
3.) Plot the absorbance measurements against the corresponding concentrations to
create a calibration curve.
4.) Measure the absorbance of an unknown sample in the spectrophotometer.
5.) Use the calibration curve to find the concentration of the substance in the
unknown sample.
,Use Beer's law (A = εℓC) to relate
experimental measurements or to calculate
an unknown value
Beer's Law equations can be found on the given equation sheet
Know how to choose the optimum
wavelength (or color) of light to analyze each
color within a sample that contains a mixture
of several colored solutes (e.g. the yellow
and blue components of a green dye mixture)
Choosing the wavelength at maximum absorption is most important when analyzing
a mixture of several different colored solutes.
Lab 4 — Molecular Geometry and Molecular
Visualization
, Draw the Lewis structure for a molecular or ionic
formula, showing all bonds and all lone pairs of
electrons
Look at the attached examples you silly goose
Understand when resonance structures are
relevant and draw their Lewis structures
you silly goose
Determine central atom hybridization,
electron-pair geometry, and molecular
geometry for a molecule or ion
WITH CORRECT/ACCURATE ANSWERS
Calculate the absorbance (A) of a sample
from measured transmission data (%T) for
that sample
Beer's Law
Absorbance = Negative Log Base 10 of Transmittance
Make a spectrophotometer calibration curve
(with knowns) and use it to find an
unknown's concentration
1.) Prepare a series of standards with known concentrations of the substance of
interest.
2.) Measure the absorbance of each standard in the spectrophotometer.
3.) Plot the absorbance measurements against the corresponding concentrations to
create a calibration curve.
4.) Measure the absorbance of an unknown sample in the spectrophotometer.
5.) Use the calibration curve to find the concentration of the substance in the
unknown sample.
,Use Beer's law (A = εℓC) to relate
experimental measurements or to calculate
an unknown value
Beer's Law equations can be found on the given equation sheet
Know how to choose the optimum
wavelength (or color) of light to analyze each
color within a sample that contains a mixture
of several colored solutes (e.g. the yellow
and blue components of a green dye mixture)
Choosing the wavelength at maximum absorption is most important when analyzing
a mixture of several different colored solutes.
Lab 4 — Molecular Geometry and Molecular
Visualization
, Draw the Lewis structure for a molecular or ionic
formula, showing all bonds and all lone pairs of
electrons
Look at the attached examples you silly goose
Understand when resonance structures are
relevant and draw their Lewis structures
you silly goose
Determine central atom hybridization,
electron-pair geometry, and molecular
geometry for a molecule or ion
