What's a vacuum aspirator and how will it affect the color of a solution?

Question

Originally greenish-yellow because of 1M of HCL added. 

HCO3^-(aq) <-> CO2(g) + OH- (aq)

But what happens when using a vacuum aspirator? Isn't its point to remove impurities? So how would the color change?

Would it be white?

Answer 1

Hello, Lily,

The aspirator produces a vacuum above the liquid sample. For the reaction you describe:

HCO3^-(aq) <-> CO2(g) + OH- (aq)

we can see that the CO₂ gas will be sucked away from the system. This will cause more HCO₃^- to decompose into CO₂ gas and OH^- ions in solution. As the OH^- concentration increases, the pH also increases. If there is a pH indicator in the solution, it will change color as the pH changes.

Bob