If You Exposed Water to a Lit Match, How Much Would It's pH Change...?

If the water started at 7.0If You Exposed Water to a Lit Match, How Much Would It's pH Change...?
Yes the pH goes down because of CO2... but to determine the actual pH...



Assume that the mixture of gases generated by the match is 50/50 CO2 and H2O. So once this mixture displaces all of the air in the tube, this will be the vapor phase composition at the surface of the liquid. The pressure is about 1 atm, so the PCO2 = 0.5 atm.



The link posted below shows a simple way to use Henrys law and carbonate equilibria to estimate the pH of water in equilibrium with CO2 containing gases. plugging in a PCO2 of 0.5 atm to the equations, I calculate pH 4.2.



I dont think these assumptions are good enough to say an exact pH, but I definitely think the pH is between 4 and 5.If You Exposed Water to a Lit Match, How Much Would It's pH Change...?
H2O + H2O + heat %26lt;--%26gt; H3O+ + OH-



Kw = [H3O+][OH-]



Notice that this is an ENDOTHERMIC reaction.

When you add heat, the equilibrium shifts to the right to counter the effects of the added stress (heat increase). Thus, BOTH the concentration of hydronium and hydroxide ions increase, BUT the pH remains NEUTRAL.

Thus, there is NO change in pH by heating water.



[Answer: see above]



EDIT: I would have to agree with the latter poster.

According to his formula, there is a production of acid from the formation of CO2 with water. The increase in acid causes the pH of water to drop below 7.
The pH would drop as the CO2 from the match

disolved in the water forming carbonic acid.

H2O + CO2 --%26gt; H2 CO3