Which mass law(s) is/are demonstrated by the observation that a sample of potassium chloride from chile contains the same percent by mass of potassium as one from poland? a. law of conservation of mass b. law of definite composition c. law of multiple proportions d. laws of conservation of mass and definite composition e. laws of conservation of mass and multiple proportions?

The correct answer is b. Law of Definite Composition.

A) Law of Conservation of Mass

FALSE. This law describes the masses of substances before and after a reaction as constant. Atoms only rearrange in during chemical reactions. None is destroyed nor are any new atoms created. Therefore, the total mass of reactants must always be equal to the total mass of the products.

B) Law of Definite Composition

TRUE. Sometimes called the Law of Constant Composition, this law states that regardless of the source of a compound, its composition is the same. The mass percentages of the elements that make up a particular compound is constant. KCl, in the example, will always have 1 mol of potassium ions and 1 mole of chloride per mole of the potassium chloride regardless of whether it was from Chile or Poland.

C) Law of Multiple Proportion

FALSE. This law describes how an element combines with another element to form multiple compounds. The ratio at which they combine are in whole numbers.

D) Law of Conservation of Mass and Definite Composition

FALSE. The Law of Conservation of Mass pertains to what happens to masses  of substances before and after a chemical reaction. This problem is about different sources of a compound and not about a specified chemical reaction.

E) Law of Conservation of Mass and Multiple Proportions

FALSE. The problem is about the mass percentage of compounds from different sources, not about the reaction of the compound nor other compounds formed by potassium and iodine.

Keywords: Law of Definite Proportion, Law of Constant Composition