a student combines two liquids in a beaker. she observes that the mass of the combined liquid is less than the mass of the two separate liquids. the students claims that this observation shows that matter is not conserved in chemical reactions.
This claim is incorrect. The mass of the combined liquid is less than the mass of the two separate liquids because there may have been some evaporation or spillage during the mixing process. However, matter is still conserved in a chemical reaction. In a closed system, matter cannot be created or destroyed, only transformed into different substances. So, even if the mass of the combined liquid appears to be less, the matter is still conserved overall.
