E and M formulas Notes

Presentation

What's in the pill?

Empirical and Molecular Formulas

Acetic Acid Molecular: C2H4O2

Glucose Molecular: C6H12O6

Example:

Example:

Molecular Is:

Empirical is:

Every Compound has ___ formulas

5. Apply those numbers as subscripts to the elements.

4. (If needed) Multiply until you get whole numbers

3. Divide by the smallest number

2. Convert grams to moles

1. Change the % to grams

Example: What it the empirical formula for a compound that has 50.5% S and 49.95% O?

Author's Name

Finding Empirical Formula of an unknown chemical

Percent to MassMass to Mole Divide by Small Multiply 'til whole

PoeM: An ode to learning how to write empirical formulas

Starting with the #2, work your way through the subscripts (multiplying) until you can get all whole numbers.

If you don't end up with a whole number:

What is the empirical formula for a compound that is 25.9 % Nitrogen and 74.1 % Oxygen?

An unknown compound containing only phosphorus and oxygen is 56.3% Phosphorous. What is the empirical formula?

Day 2 review problem

CS2

Empirical Formula for 15.85 % C and 84.2% S

2. You need the molar mass of Mol. Formula

3. Find the molar mass of Emp. Formula

5. Multiply # from step 4 by the Emp. Formula subscripts

1. You need the Emp. Formula

Finding the Molecular Formula

4. Divide Mol. formula mass by Emp. formula mass

What is the molecular formula (MF) for a compound that has and empirical formula of NO2 and a molar mass of 138 g.

HO

Answer

FInd the molecular formula of a compound using % composition. The molar mass of MF is 147.0 g.

Mol: C8H10O2N4

Emp:C4H5ON2

Emp: F5S Mol: F10S2

Will it fit in a pill with a volume of 0.5 mL?

The process of converting is: Particles to moles to grams to mL

Converting Molecules to Density

Answer: 0.065mL Yes it will fit.

Example: If the density of CO is 0.301 g/mL and the fatal dose of CO is 4.22 x 1020 molecules, (Molar Mass of CO is 27.955 g/mol), will the fatal dose fit into a pill with a volume of 0.9 mL?