Help with specific rotation calculations

In summary, the conversation was about determining a sugar in a solution based on the specific rotation obtained through a required calculation. The calculations were done at a wavelength of 589nm and involved optical rotation, concentration, wavelength, temperature, and pathlength. The specific rotation values for each solution were compared to known values in the CRC Handbook of Chemistry and Physics to determine the type of sugar present.
  • #1
oreolrs
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Help with specific rotation calculations (urgent)

Homework Statement



I need help determining a sugar in solution based on the specicific rotation i gained through the required calculation this was done at 589nm

Homework Equations



[α] = σ/cl

The Attempt at a Solution


Solution A Solution B Solution C
589nm +2.004 +4.034 -4.434
578nm +2.004 +4.034 -4.438
546nm +2.350 +4.576 -4.995
436nm +3.924 +7.578 -8.195
365nm +6.000 +11.469 -12.280
were the polarimeter readings

the calculations done for specific rotation were as followings
[α]λT = σ/cl where σ:eek:ptical rotation measured,
c: concentration w/v - 0.05
λ:wavelength measured at
T:Temperature of the sample when measured – 30.05
L:length of pathway for light – 1cm
Solution A: 589 & 578nm - +2.004/(0.5)(0.1)= 40.08
546nm - +2.350/(0.5)(0.1) = 47
436nm - +3.924/(0.5)(0.1) = 78.48
365nm - +6.000/(0.5)(0.1) = 120
Solution B: 589 & 578nm - +4.034/(0.5)(0.1) = 80.68
546nm - +4.576/(0.5)(0.1) = 91.52
436nm - +7.578/(0.5)(0.1) = 151.56
365nm – +11.469/(0.5)(0.1) =229.38
Solution C: 589nm - -4.434/(0.5)(0.1) = -88.68
578nm - -4.438/(0.5)(0.1) = -88.76
546nm - -4.995/(0.5)(0.1) = -99.9
436nm - -8.195/(0.5)(0.1) = -163.9
365nm - -12.280/(0.5)(0.1)= -245.6
Having been trying to find the specific rotation online or in a crc handbook to determine the type of sugar in each solution.Does anyone know where i can find such information
 
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or have any suggestions? The specific rotation of a given sugar depends on the temperature, wavelength, concentration, and pathlength used in the experiment. The only way to accurately determine the type of sugar in the solutions is to compare the specific rotation values you have calculated with known specific rotation values for each type of sugar. You can find these values in the CRC Handbook of Chemistry and Physics or other reference books.
 

1. What is specific rotation and why is it important in chemistry?

Specific rotation is a measure of the optical rotation of a substance in solution. It is important in chemistry because it provides information about the structure and purity of a compound, and it can also help determine the concentration of a solution.

2. How is specific rotation calculated?

Specific rotation is calculated by taking the observed rotation of a substance, correcting for the length of the sample cell, and dividing by the concentration of the solution and the path length of the light through the solution.

3. What units are used for specific rotation?

Specific rotation is typically reported in degrees per decimeter per gram (°/dm/g), although it can also be expressed in radians per meter per kilogram (rad/m/kg).

4. How can I use specific rotation to identify a compound?

Each compound has a unique specific rotation value, so by comparing the specific rotation of an unknown compound to a database of known values, the compound can be identified.

5. Are there any factors that can affect the accuracy of specific rotation calculations?

Yes, there are several factors that can affect the accuracy of specific rotation calculations, including temperature, solvent, sample purity, and concentration. It is important to control these factors as much as possible to ensure accurate results.

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