Question

Is mass conserved when 200 g of water undergoes a physical change? Use complete sentences to support your answer by explaining how this can be demonstrated.

A) Yes, mass is conserved in a physical change, as the total mass of the water remains the same before and after the change, which can be demonstrated by measuring the mass.
B) No, mass is not conserved in a physical change, as some mass may be lost during the process.
C) Mass conservation depends on the specific physical change and cannot be generalized.
D) Mass conservation is only relevant in chemical changes, not physical changes.

Answer 1

Mass is indeed conserved when 200 g of water undergoes a physical change. The law of conservation of matter ensures that the total quantity of matter remains unchanged during any physical change, such as changing states from solid, liquid, to gas. This is because the composition and number of molecules remain the same throughout the process.

Step-by-step explanation:

Yes, mass is conserved when 200 g of water undergoes a physical change. This can be demonstrated through various processes that water might undergo, such as freezing, melting, or evaporating. Despite these physical changes — where water changes its state from solid to liquid or gas, or vice versa — the substance itself remains water, meaning that the number of water molecules stays the same.

Energy changes may occur during these physical changes, but they do not affect the mass of the water itself. The law of conservation of matter states that there is no detectable change in the total quantity of matter present when matter changes state.

For example, if water vapor (steam) condenses into liquid water, it is still water, just in a different physical state. Moreover, if you weigh a closed system before and after such a physical change occurs, the mass will remain constant. This principle is not only applicable to the physical changes of water but is a universal concept in all physical and chemical changes, except for those involving nuclear reactions, where matter-energy conversions can be significant.