KaiserScience

Briggs Rauscher fill-ins

Briggs–Rauscher worksheet fill-ins:

…contrary to the 2nd law of thermodynamics, which asserts that: once a chemical rxn reaches it’s end, it will not change back (unless extra energy is added)

_______________________________

Just as the clock is running down while it’s hands rotate: the chemical rxn runs down to equilibrium

Hypothesis: Unlike regular chemical Rxns, we may be able to arrange a reaction which cycles back-and-forth between two states.

Testing our hypothesis: Add chemicals in correct sequence. Test for chemical changes (color, temperature, gas bubbles)

Initial conditions:

aqueous solution (aq) means: dissolved in water

Chemical reactions

Oxidation of hydrogen peroxide by iodic acid:

5 H2O2 (aq) + 2 HIO3 (aq) –> 5 O2 (g) + I2 (aq) + 6 H2O (l)

Oxidation of of iodine by hydrogen peroxide:

5 H2O2 (aq) + I2 (aq) –> 2 HIO3 (aq) + 4 H2O (l)

_____________ or________________

5 H2O2 (aq) + I2 (aq) –>

2 HIO3 (aq) + 4 H2O (L)

5 H2O2 (aq) + 2 HIO3 (aq) –>

5 O2 (g) + I2 (aq) + 6 H2O (L)

_____________ or________________

http://inside.mines.edu/~dwu/classes/CH353/labs/ClockCKS/Wet%20Lab%204/Oscillating%20Reactions.pdf

5 H2O2 (aq) + 2 IO3 – (aq) + 2 H+ (aq) -> I2 (aq) + 5 O2 (g) + 6 H2O (l)

5 H2O2 (aq) + I2 (aq) -> 2 IO3 – (aq) + 2 H+ (aq) + 4 H2O (l)

The net result is: 2 H2O2 (aq) -> O2 (g) + 2 H2O (l)

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