Experiment9:碘鐘實驗－Shawn910018的部落格

Experiment date: 2013/12/21

Principle:

Rate of reaction can be show as Rate = K[A]^x[B]^y. And then the order of reaction should be x & y, rate constant is a stationary value.

This experiment is trying to find the rate formula between S₂O₈^2- and I^- and use S₂O₃^2- to notice the time. I₂ and S₂O₃^2- can be reaction in a high speed that can even see I₂ as I^-. And when S₂O₃^2- is gone, I^-and I₂ will become I₃^-and the liquid will become dark blue.

We can find the order of reaction by change a single object’s concentration and see the reaction rate’s change.

Chemicals and their Properties:

Na₂S₂O₃ (CAS 7772-98-7):	158.09774 g/mol d:1.84g/cm³ mp: 48.3 °C
K₂S₂O₈ (CAS 7727-21-1 ):	270.322 g/mol 2.477 g/cm³ mp: <100°C (Decomposition)
NaCl (CAS 7647-14-5):	58.44277g/mol 2.16 g/cm³ mp:801°C bp:1465°C
K₂SO₄ (CAS 7778-80-5):	174.259 g/mol (without water) 2.66g/cm³ (without water)
NaI (CAS 7681-82-5):	149.89 g/mol 3.67 g/cm³ mp:660°C bp:1304°C

Tools:

1. Pasteur pipette (10mL/25mL)

2. Timer

3. Cork

4. Erlenmeyer flask

Safety and Waste Disposal:

Safety : Always wear your coat, gloves and eye protection.

Procedure:
1. Prepare 10 Erlenmeyer flask (50mL) and get the Order of reaction.
2. Put the right amount of Na₂S₂O₃NaCl NaI in the Erlenmeyer flask.
3. Take 5mL K₂SO₄ and put in the Erlenmeyer flask.
4. Put in 5mL K₂S₂O₈ and at the same time, start the timer.
5. Stop the timer when the liquid become black.
6. Repeat the step. 1 to step.5.
7. Find out the order of reaction and rate constant.