Structure 1.4.4 Empirical + Molecular Formulas and % Composition

Question 1

Define Percent Composition

Answer 1

the relative % of each element in a chemical formula or sample

Question 2

% composition by chemical formula formula

Answer 2

% any element = # of atoms/ions x Ar / total mass of compound x 100

Question 3

% composition by experimental mass formula

Answer 3

% element = mass of element/ mass of compound x 100

Question 4

define empirical formula

Answer 4

the empirical formula gives the simplest ratio of atoms/ions of elements in a compound or molecule

Question 5

differences b/w compound vs molecule

Answer 5

compounds are ionic (metal) and molecules are molecular (all non metals)

Question 6

should ionic compounds be represented as the empirical formula or the molecular formula

Answer 6

ionic compounds should always be represented as the empirical formula as we are representing the formula unit of a large structure of repeating ions

Question 7

what does the molecular formula show

Answer 7

shows the actual # of atoms in the formula and is what distinguishes different molecules from eachother

Question 8

define molar mass

Answer 8

the true mass of molecular formula

Question 9

formula for finding the molecular formula using its molar mass and the empirical formula

Answer 9

X = molar mass/ empirical formula mass

Question 10

assumptions made in combustion analysis

Answer 10

1. all of the C in the hydrocarbon is converted to CO2
2. All of the H in the hydrocarbon is converted to H2O