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Identify the mass law that each of the following
Chapter 1, Problem 7P(choose chapter or problem)
Identify the mass law that each of the following observations demonstrates, and explain your reasoning:
(a) A sample of potassium chloride from Chile contains the same percent by mass of potassium as one from Poland.
(b) A flashbulb contains magnesium and oxygen before use and magnesium oxide afterward, but its mass does not change.
(c) Arsenic and oxygen form one compound that is 65.2 mass % arsenic and another that is 75.8 mass % arsenic.
Questions & Answers
QUESTION:
Identify the mass law that each of the following observations demonstrates, and explain your reasoning:
(a) A sample of potassium chloride from Chile contains the same percent by mass of potassium as one from Poland.
(b) A flashbulb contains magnesium and oxygen before use and magnesium oxide afterward, but its mass does not change.
(c) Arsenic and oxygen form one compound that is 65.2 mass % arsenic and another that is 75.8 mass % arsenic.
ANSWER:Here, we are asked to identify the mass law and explain the reasoning.
(a) Given: A sample of potassium chloride from Chile contains the same percent by mass of potassium as one from Poland.
Here, it is given that potassium chloride contains the same percent by mass of potassium, regardless of its source. This refers to Law of Definite Composition.
Law of definite composition states that a chemical compound, no matter what its source, is composed of the same elements in the same proportion (fractions) by mass.