Question

why trimethyl acetic acid doesnot evolve co2 gas?

Answer 1

Doesn’t it? What temperatures and conditions are we talking about, here? Pivalic acid (aka trimethylacetic acid) is weak, pKa 5.03, but not so weak that it can’t displace the carbonic acid under the right conditions. In particular I would expect that boiling a solution of sodium carbonate and trimethylacetic acid together would indeed result in the CO2 being evolved. But yes, at room temperature and with an ordinary saturated solution of the acid (solubility only 25g per liter) I expect that the CO2 would remain in solution.

Answer 2

Hey mate here is your answer ..
This is because for carbon dioxide gas to be evolved from sodium bicarbonate, the acid must be stronger than the bicarbonate ion, HCO3-, in order to protonate it, and form carbonic acid, which rapidly dehydrates to evolve carbon dioxide gas. Hence the equation (should the acid be stronger than HCO3-) would be:

HCO3- + H+ => H2CO3 <=> CO2 + H2O
Hope you understand please mark my answer in brain list