PASCO’s Polarimeter has both low energy Bluetooth® and USB connectivity, so it works on your iPad®, Chromebook™, tablets, and computers. It is ideal for introductory Organic and Biochemistry experiments with chiral compounds. Plane polarized light passes through a vertical sample of solution then through an analyzer and a detector. Finding the angle from start to where the optimum light is transmitted through the cross polarizer gives the optical rotation. The rotation can be used to calculate concentration and the amount turned per g/ml dissolved (specific rotation) is an intrinsic property that can be used to differentiate molecules or determine racemic mixtures.
The speed of light around chiral atom centers is anisotropic (slower for light vibrating in one dimension than that at 90 degrees). This causes a component of the oscillation, say the horizontal portion, to slow down causing the composite plane of oscillation to rotate as it passes through the solution. A second polarizing film is rotated until a maximum amount of light makes it through to the detector. The angle from initial orientation to where it was deflected is considered the optical rotation. A single color of light is used because much like red light refracts less than violet through a prism, in an optically active solution, red is rotated less than orange, less than green, then blue and violet. This can be observed in the polarizer demo set (OS-9477A) as a solution of Karo syrup changes color between the two larger polarizers from red to violet as the cross polarizer is rotates to let the next color through the appropriately aligned color.
Lab Activities & Experiments
- Sucrose Concentration through Polarimetry
- Students use a polarimeter to determine the unknown concentration of a sucrose solution.
- Kinetics of Sucrose Rotation
- Students use a polarimeter determine reaction order and rate constant of an acid-catalyzed sucrose hydrolysis reaction and an invertase-catalyzed reaction.
- Specific Rotation of Sucrose
- Students use a polarimeter to experimentally determine the specific rotation of the sucrose molecule.
- Determination of Sucrose Concentration through Polarimetry: Biot’s Law
- Students use a polarimeter and Biot’s law to determine the unknown concentration of several sucrose solutions.
- Equilibrium of Glucose Mutarotation
- Students use a polarimeter to determine the α- and β-anomer concentrations of a D-glucose solution at equilibrium, and calculate the equilibrium constant.
- One Sample Cell
|Bluetooth® and USB connectivity|
|589 nm LED light source|
|Accuracy = ± 0.09º optical rotation|
|SPARKvue- and Capstone-compatible|
|Industry-standard, horizontal polarimeter sample cell (100 mm)|
Battery and Logging
|Stored Data Points Memory (Logging) 1||Not Supported|
|Battery – Connected (Data Collection Mode) 2||>11 hr|
|Battery – Logging (Data Logging Mode) 3||Not Supported|
1 Minimum # of data points with all measurements enabled, actual results depend on enabled measurements.
2 Continuous use in a connected state until battery failure, actual results will depend on sample rate, active measurements, and battery condition.
3 Logging until battery failure, actual results will depend on sample rate, active measurements, and battery condition.
* Normal classroom use is the sensor in active use for 20min/lab for 120 lab periods/yr.