DIDACTICALLY CORRECT SENSORS FOR DIGITAL LABS Denis Zhilin, Moscow Institute for Open Education, School #192, [email protected] Oleg Povalyaev, Scientific.

DIDACTICALLY CORRECT SENSORS FOR

DIGITAL LABS

Denis Zhilin,Moscow Institute for Open Education,School #192,

[email protected]

Oleg Povalyaev,Scientific Entertainment Co, Moscow

[email protected]

THE DIGITAL LABSA system allowing to measure different

analogous parameters, put them into digital form, store, visualize and process

THE BENEFITSComputer takes routine procedures

reducing cognitive overloadFast measurements can follow quick

processesVisualizing parameters that humans do not

feel (pH)

THE PROBLEMThe choice of

sensors: rather available

than didactically necessary

• temperature• pH• conductivity• redox-potential• p(I)• optical density• gas pressure• dissolved O2

REPLACE SENSOROR CHANGE CURRICULUM?

Gas pressure sensor is used to develop the concept of stoichiometry,

butn = pV/(RT)

the change of pressure depends on

volume that can be very different

connection between gas amount and gas pressure causes cognitive overload

Volume is proportional to gas amount

(always p 1 atm, T 290K)

No cognitive overload

SOLUTION: GAS VOLUME SENSOR

HOW TO SEE WHAT IS HAPPENING?

Colorimeters with 3 mL cuvettes:

The cuvettes are concealed

No links between It’s impossible toobservations and add something tofigures the cuvette

No sense of Limitations forparameters forms experimental

design

SOLUTION: GATE SENSOR+ one can see

everything+ one can add

reactantsProblems with

adjusting?No! The side light

is taking into account

Another possible solution:immerse probe with optical fiber and mirror

HOW TO OPERATE?Drop counters for titration: - Requires adjustment- Requires calibration for each titrant- Can’t add large volumes of titrant

Too much time for struggling with the

sensor cognitive overload

No waiting time between adding a drop and fixing parameter value

Inaccurate results

SOLUTION: SYRIGNE SENSOR

Titrant could be added at any rate

Requires calibration only when the syringe type is changed

One can wait after adding drops to let the drop distribute in the system

COMPLICATED APPARATUS

pH-metric + colorimetric titration(Ex: checking the applicability of indicators)

THANK YOU FOR YOUR ATTENTION

Denis Zhilin,Moscow Institute for Open Education,School #192,

[email protected]