Trini adds 10g of baking soda to 100g of vinegar. The mixture begins to bubble. When the bubbling stops, trini finds the mass of the resulting mixture. She determines its mass is 105g. Why has the mass changed?
A. A gas has formed and left the mixture
B. Vinegar evaporated during the experiment
C. Mixtures are always less massive than their parts.
D. Matter was destroyed when vinegar reacted with baking soda.
D is NOT correct
from 2013 and no right answers? im already failing this test
The baking soda reacts with the vinegar, producing a gas (the bubbling). When the bubbling stops, this indicates that the gas has evaporated from the mixture (left).
A. A gas has formed and left the mixture
The correct answer is A. A gas has formed and left the mixture.
When Trini adds baking soda to vinegar, a chemical reaction called a neutralization reaction occurs. In this reaction, the baking soda (sodium bicarbonate, NaHCO3) reacts with the vinegar (acetic acid, CH3COOH) to produce carbon dioxide gas (CO2), water (H2O), and a sodium acetate solution.
The bubbling that Trini observes is the result of the carbon dioxide gas being released. The gas is formed as a product of the chemical reaction and it escapes from the liquid mixture. As a result, the mass of the mixture decreases because the gas no longer contributes to the overall mass of the system.
Option B, vinegar evaporating, is incorrect because vinegar does not evaporate at room temperature and normal atmospheric pressure. Evaporation occurs when a liquid changes into a gas, but in this case, the mass change is mainly due to the formation of gas, not evaporation.
Option C, mixtures are always less massive than their parts, is incorrect because the mass of a mixture can vary depending on the specific substances and their quantities. This statement is a generalization that does not apply in this particular scenario.
Option D, matter being destroyed, is also incorrect. In a chemical reaction, matter is not destroyed but rather transformed into new substances. The mass is conserved, meaning that the total mass of the reactants (baking soda and vinegar) should be equal to the total mass of the products (resulting mixture).
Therefore, the correct explanation for why the mass has changed is that a gas (carbon dioxide) has formed and left the mixture.