Microscale chemistry is the reduction of chemical use to the lowest level at which experiments can be effectively performed. It offers a safer way to perform chemical experiments by using smaller quantities of chemicals. Microscale experiments are conducted without compromising the quality or standard of chemical applications in educational institutions and the experimental industry.
Benefits of Microscale Chemistry:
- Reduces chemical use by promoting waste reduction at the source.
- Improves laboratory safety (air quality, reduced exposure, and spills)
- Saves money.
- Decreases experiment time.
- Teaches students alternatives to conventional chemistry.
How to convert to true microscale chemistry
Converting to microscale chemistry involves an initial investment of glassware and specialized pipets. This change is necessary due to the minute amounts of chemicals used in the reactions. Where a 100 ml flask might have worked in conventional chemistry, a 10 or 20 ml flask is more appropriate for microscale chemistry. Specialized pipets calibrated to receive only a small amount of a chemical are needed to accurately measure the minute amounts used in this type of chemistry.
If you cannot convert to true microscale chemistry, try decreasing experimental quantities by a third or half. A 50 percent reduction in quantities can usually be achieved with conventional glassware. Such scale reductions may require a few trial runs to ensure desired experimental results-a good exercise for students who volunteer for extra credit lab work. (Caution: instructor supervision is critical!)
Use these best management practices to teach and practice other resource efficient laboratory procedures.
- Conduct experiments that use the least toxic or non-toxic ingredients.
- Use solvents and other hazardous materials sparingly.
- Monitor experimental reactions and add additional chemicals only as necessary.
- Conserve water by turning off the faucet between lengthy rinses.
- Pre-weigh chemicals for students.
- Have students work in teams.
- Demonstrate experiments yourself when applicable.
- Follow safety practices and applicable laws and policies.
- Stress the importance of minimizing waste to school administrators.
- Recycle chemicals when possible.
- Adopt centralized chemical management to eliminate the unnecesary double purchase of chemicals.
Example Microscale Experiment
Redox Titration of Manganese
- Using a graduated or volumetric pipette, place 1.00 (± 0.01) mL of 0.0100M KMnO4 solutions into each of three 10-mL flasks. Label as A, B, and C.
Acid Solution Titration.
- Add 1.0 ml of 1M H2SO4 to flask A. Charge a microburet with 0.0200M NaSO3 solutions and slowly titrate the permanganate solution drop by drop until the purple color of the solution disappears. Record the volume of NaHSO3added.
Neutral Solution Titration.
- Recharge the microburet with 0.0200M NaHSO3 solutions. Record initial volume and titrate the KMno4solution in flask B. The purple color of permanganate will change to brown suspension of MnO2at the endpoint. Record the final volume.
Basic Solution Titration.
- Add 1.0 ml of 1 M NaOH to the permanganate solution in flask C. Recharge the micro buret with NaHSO3solution. Record initial volume. Titrate to dark green-colored endpoint of MnO4-2.
The remainder of the experimental calculations and exercises are provided in the textbook. (Taken from Szafran, et al., 1993 p. 270)