Conservation of Mass

How does mass change during a chemical or physical change?

• It increases

• It decreases

• It remains the same

• It cannot be determined

What would you expect the mass of the carbon dioxide gas to be? Explain your reasoning.

• Depends on the volume and temperature of the gas

• Equal to the mass of the reactants

• Can be calculated using the molar mass of CO₂

• Not possible to determine in an open system

What does the law of conservation of mass state?

• Matter can neither be created nor destroyed

• Energy can neither be created nor destroyed

• Mass is always conserved in a chemical reaction

• Mass and energy are interchangeable

Explain how the law of conservation of mass applies to garbage.

• It implies that garbage can neither be created nor destroyed, but can change forms.

• It suggests that garbage volume increases over time without bounds.

• It indicates that garbage can be completely destroyed.

• It means that garbage mass decreases when recycled.

Was matter lost or gained during this reaction? Explain how you could prove this by taking measurements.

• Matter was lost, and this can be proven by showing a decrease in total mass.

• Matter was gained, and this can be proven by showing an increase in total mass.

• No matter was lost or gained; this can be proven by showing no change in total mass.

• It cannot be determined without further chemical analysis.

The left side of the equation shows one atom of S, two atoms of H, and four atoms of O. How many atoms of each element are on the right side of the equation? How does this provide evidence for the law of conservation of mass?

• One atom of S, two atoms of H, and four atoms of O, demonstrating the law of conservation of mass.

• Two atoms of S, four atoms of H, and two atoms of O, violating the law of conservation of mass.

• One atom of S, two atoms of H, and two atoms of O, violating the law of conservation of mass.

• The number of atoms for each element varies, not providing clear evidence for the law of conservation of mass.

When an ice cube melts, which of these quantities will change?

• The number of atoms it contains

• Its mass

• Its volume

• All of the above

• None of the above

Explain what happens to the number of atoms, the mass, and the weight of the water in a glass when it evaporates.

• The number of atoms decreases, and both mass and weight decrease.

• The number of atoms remains the same, but mass and weight decrease.

• The number of atoms, mass, and weight all remain the same.

• The number of atoms, mass, and weight all decrease.

Is mass conserved when chemical and physical changes take place?

• Yes, because the total mass of substances involved in a reaction remains unchanged.

• No, mass can be created or destroyed in chemical reactions.

• Yes, but only in physical changes, not chemical changes.

• No, because mass is only conserved in closed systems.

What would you have to do to prove that matter is conserved when a piece of paper is burned?

• Measure the mass of the paper before and after burning

• Observe the color change of the paper

• Calculate the temperature of the flame

• Compare the size of the paper before and after burning