Chapter 2.2: The Observations that led to an atomic view of matter

Question 1

Law of mass conservation

Answer 1

1. Matter cannont be created or destroyed it just changes form
2. Total mass of substances does not change during a chemical reaction

Question 2

example of mass conservation

Answer 2

180g Glucose + 192g Oxygen gas –> 264g CO2 + 108g H2O

372g material before = 372 g material after

Question 3

law of definite (constant) composition

Answer 3

no matter the source, a particular compound is composed of the same elements in the same parts by mass (fractions by mass)

Question 4

fraction by mass

Answer 4

part of the compound’s mass that each element contributes

mass of each element)/(mass of each compound

Question 5

percent by mass

Answer 5

fraction by mass expressed as a percentage

((mass of each element)/(mass of compounds)) x100 = mass%

Question 6

Sum of mass fractions (mass percents)

Answer 6

1.00 part (100%) by mass because mass fraction is fixed no matter what the size of the sample is

Question 7

Fraction to find actual mass of the element in any sample of the compound

Answer 7

Mass of Element = mass of compound x [(part by mass of element)/(one part by mass of compound)]

Question 8

mass of element in sample

Answer 8

=mass of compound in sample x [(mass of element in compound)/(mass of compound)]