[xtheunknown0]

Hello,

Our class added hydrochloric acid to sodium thiosulfate and varied concentration of acid and temperature to see what factors affect rate of reaction.

I have a question asking how to show that HCl is not a catalyst in this reaction.

My first question is: is SO₂(aq) or SO₂(g) produced? Above the given equation reads "[the reaction] produce(s)...sulfur dioxide gas" but the equation 'uses' SO₂(aq).

Because if gas is produced, my next question is: how should I evacuate the gas?
Otherwise, I could (just) immediately add some sodium carbonate and see if any gas (CO₂) forms?

TIA,
xtheunknown0

[DevaDevil]

write down the reaction equation.

What role does the HCl play? Is it consumed?
This will answer the question of catalysis for you

[vmelkon]

A catalyst is something that facilitates a chemical reaction by reducing the energy required for a reaction to take place. At the end of the reaction, the catalyst does not get consumed. Example, the catalyst in cars would be Pt-Rh and another section with Pt-Pd. The catalyst lasts forever. It might get covered with debris that render it ineffective, but the catalyst is always there.

"Because if gas is produced, my next question is: how should I evacuate the gas?"
I don't know what your equipment is. If it is a test tube, do it in a fume hood.
If it is in a close container, open the valve.

[Vidya]

Hi
Catalyst is always regenerated after the reaction and is not used up during the reaction.
SO2 (aq) is actually H2SO3 . SO2(g) gas escapes the mixture during the reaction if the system is open.