[room302]

Hey guys   , I've just conducted an experiment for a lab write up, and now I'm on my Discussion/Conclusion part. The experiment involved 3 main components -> an empty 2L plastic bottle, sodium bicarbonate, vinegar

, in addition the rest of the equipment -> a piece of thread(string), some tissue paper , tape, bottle cap, and a paper clip

Measurements were measured by a centigram balancer

Basically, my procedures were simple.
First vinegar was poured into the bottle about a cup and a half.
Then about 1 tbsp of Sodium bicarbonate was placed inside (wrapped) some tissue paper
After that I taped the string to the bottle cap, and from there i taped the string to the paper clip. The paper clip was used as a hook to hook on the sodium bicarbonate (wrapped inside the tissue paper). The sodium bicarbonate was placed inside the plastic bottle (hanging from thread) and was measured using a centigram balancer. I got 157.39g

After that i shook the bottle, and the sodium bicarbonate fell and reacted with the vinegar. Carbon dioxide was released, and a solution was created. I measured the bottle after that, and i got 157.37g. The difference between the 1st measurement (before) and 2nd measurement (after) was 0.02. Not much of a significant change in mass. Despite the volume change.. why is the mass still the same?

I'm a bit lost on how to explain my results using the law conversation of mass.
My theories are that micro particles are exerting more pressure, and then perhaps some sort of equilibrium is reached? Not quite sure, hope you guys can help me out.

Help will be appreciated thank you.

Bob

P.S I've done the experiment several times, and still noticed no significant change in the mass. What law of conversation of mass is this? Can someone explain to me what the microparticles are doing inside the closed bottle?

[agrobert]

Are you uncertain on why the volume changed?

Think about the solubility of carbon dioxide in water.  Do you drink soda?

Your mass shouldn't change if your bottle was sealed.

If your bottle was open or leaks, you lost mass to carbon dioxide evolution and exit.

[room302]

I assume the volume changed because more micro particles are exerting pressure, but I'm uncertain of why the mass is the same, after the sodium bicarbonate mixes with the vinegar. I don't know how to explain it in law of conversation of mass terms. Does this involve boyle's law or something.

How do i explain it using the law of conversation of mass. Can someone explain what the micro particles are doing inside the bottle?

Thanks.

[Borek]

What does the law of mass conservation tells you? Can you quote it verbatim?

[room302]

it states "that the mass of a closed system will remain constant, regardless of the processes acting inside the system."

But i don't get How this works... what are the micro particles doing inside the closed system? Was there some equilibrium?