1. Mass Relationships in Chemical Formulas

2. Put the following chemical formulas into two categories
Put the following chemical formulas into two categories. Be able to tell me why/how you separated them.
C6H6, CH4, H2O, N2O4, C2H8, H2O2, NO2, CH  

3. A molecular formula shows the exact number of atoms of each element in the smallest unit of a substance.
An empirical formula shows the simplest
whole-number ratio of the atoms in a substance.
H2O
molecular
empirical
H2O
CH2O
C6H12O6 O O3
NH2
N2H4
C2H5
C4H10
Butane

4. Write the empirical formulas for the following molecules:
acetylene (C2H2), which is used in welding torches
glucose (C6H12O6), a substance known as blood sugar
nitrous oxide (N2O), a gas that is used as an anesthetic gas (“laughing gas”) and as an aerosol propellant for whipped creams.

5. Percent Composition and Empirical Formulas
Steps:
Percent to mass
Mass to moles
Divide by small
Multiply ‘til whole
**If you have a 100g sample, the percent composition is the same as the mass

6. Ascorbic acid (vitamin C) cures scurvy.
It is composed of percent carbon (C), 4.58 percent hydrogen (H), and percent oxygen (O) by mass.
Determine its empirical formula.

7. Molecular Formula Steps: Find empirical formula
Determine the molar mass of the empirical formula
Find multiplier (molar mass given/empirical molar mass)
Multiply empirical formula subscripts by the multiplier

8. A sample of a compound contains 30. 46 percent nitrogen and 69
A sample of a compound contains percent nitrogen and percent oxygen by mass, as determined by a mass spectrometer.
In a separate experiment, the molar mass of the compound is found to be between 90 g and 95 g.
Determine the molecular formula and the accurate molar mass of the compound.

9. A compound composed of 40. 68% carbon, 5. 08% hydrogen and 54
A compound composed of 40.68% carbon, 5.08% hydrogen and 54.24% oxygen has a molar mass of g/mol. Determine the empirical and molecular formula.

10. Combustion Analysis
—technique used to determine elemental composition (empirical/molecular formula) of an organic compound by combusting (reacting with O2) it under conditions where the resulting products can be quantitatively analyzed.
Example:
Combust 11.5 g ethanol
composed of: C, H, O
Collect 22.0 g CO2 and 13.5 g H2O

12. Suppose a substance has been prepared that is composed of carbon, hydrogen and nitrogen. When g of this compound is reacted with oxygen, g of carbon dioxide and g of water are collected. The molar mass of the compound is g/mol. Determine the formula of the compound.