What causes the chemical reaction to stop between baking soda and vinegar?

The chemical reaction between baking soda (sodium bicarbonate) and vinegar (acetic acid) does not completely stop. It reaches a point of equilibrium, where the forward and reverse reactions are occurring at the same rate, so there is no net change in the concentrations of the reactants and products.

The reaction can be represented as follows:

NaHCO3 (sodium bicarbonate) + CH3COOH (acetic acid) → CO2 (carbon dioxide) + H2O (water) + CH3COONa (sodium acetate)

At the beginning of the reaction, there is a high concentration of baking soda and vinegar, so the forward reaction occurs rapidly, producing carbon dioxide gas, water, and sodium acetate. As the concentrations of the reactants decrease, the rate of the forward reaction slows down.

At the same time, the reverse reaction also occurs, where carbon dioxide, water, and sodium acetate react to form baking soda and vinegar. As the concentrations of the products increase, the rate of the reverse reaction increases.

Eventually, the rates of the forward and reverse reactions become equal, and the reaction reaches equilibrium. At this point, there is still a small amount of baking soda and vinegar present, but their concentrations remain constant because the forward and reverse reactions are occurring at the same rate.

In summary, the chemical reaction between baking soda and vinegar does not completely stop, but it reaches a point of equilibrium where the forward and reverse reactions are occurring at the same rate, so there is no net change in the concentrations of the reactants and products.