Mole GRAM FORMULA MASS MOLES TO GRAMS AND GRAMS TO MOLES

Mole The amount of any pure substance that contains as many atoms, molecules, ions, or other elementary units as the number of atoms in 12 grams of Carbon-12 This is equal to 6.02 x particles = Known as Avogadro’s number.

Solving for Gram formula Mass To solve for the mass of one mole of a compound: Steps: 1. Identify each of the elements in the compound Example: H2OH2O H O

Solving for Gram formula Mass To solve for the mass of one mole of a compound: Steps: 1. Identify each of the elements in the compound 2. Identify how many atoms of each element in the compound Example: H2OH2O H = 2 O = 1

Solving for Gram formula Mass To solve for the mass of one mole of a compound: Steps: 1. Identify each of the elements in the compound 2. Identify how many atoms of each element in the compound 3. Using the periodic table, find the mass for each of the elements Example: H2OH2O H = 2 x g O = 1 x 16 g

Solving for Gram formula Mass To solve for the mass of one mole of a compound: Steps: 1. Identify each of the elements in the compound 2. Identify how many atoms of each element in the compound 3. Using the periodic table, find the mass for each of the elements 4. Multiply the mass times the number of atoms for each of the elements Example: H2OH2O 1.H = 2 x g = g O = 1 x 16 g =16.00 g

Solving for Gram formula Mass (Molar mass) To solve for the mass of one mole of a compound: Steps: 1. Identify each of the elements in the compound 2. Identify how many atoms of each element in the compound 3. Using the periodic table, find the mass for each of the elements 4. Multiply the mass times the number of atoms for each of the elements 5. Add the masses. Answer should be in grams per Mole Example: H2OH2O 1.H = 2 x g = g O = 1 x 16 g =16.00 g = g/mole

How to determine the number of moles in a given mass (grams to moles). Steps: 1. Find the formula mass of the given compound 2. Use the fence method to convert grams to moles Using the fence method you must identify the conversion factor (amount of mass in one mole of the molecule) 3. Divide the total grams by the grams per mole. 4. Answer should be in Moles

How to determine the amount of mass in a given number of moles (moles to grams) Steps: 1. Find the formula mass of the given compound. 2. using the fence method find the conversion factor. 3. Multiply the grams per mole times the moles to get grams. 4. Answer should be in grams.

Solving for the percent composition. What is the percentage of each of the elements found in a compound? 1. Find the molar mass of the compound 2. Divide the amount of mass of each element by the total mass of the compound and multiply times 100% 3. Check that the addition of all of the percentages equal to 100%

Stoichiometry Stoichiometry is the study of the quantitative relationships or ratios between two or more substances undergoing a physical change orchemical change (chemical reaction).physical changechemical changereaction The word derives from the Greek words: stoicheion (meaning "element") and metron (meaning "to measure"). Most often, stoichiometry calculations deal with the mass or volumes of products and reactants. Source:

Mole – Mole Problems Problem: How many moles of oxygen are needed to completely react with 2.25 moles of propane (C 3 H 8 )? C 3 H 8 + 5O 2 → 3CO 2 + 4H 2 O STEPS: 1.Check if the chemical reaction is balanced. 2.Write on the equation what is given in the question. 3.Solve for moles of desired compound using the fence method.

Mass – Mass problems How many grams of carbon monoxide are necessary to react completely with 50.0 grams of iron (III) oxide? Fe 2 O 3 + 3CO → 2Fe + 3CO 2 STEPS: 1.Check if equation is balanced. 2.Write what is given in the question on the equation. 3.Solve for formula mas (mass per mole) of the compounds mentioned in the question. 4.Solve for moles of the starting substance. 5.Convert moles of the given substance to the substance in question. 6.Convert moles to moles 7.Convert moles to mass of the desired compound.