Mass Stoichiometry Solutions

Stoichiometry

the relationship between substances that are included in reactions and solutions. This includes conversions of different measurements in order to show and give accurate proportions in reactions.

All about converting

Think of stoichiometry as converting feet to inches or minutes to hours and vice versa. For example, if you have 90ft you know that there are 12inches in one foot; therefore you should have 1080inches in total. The same goes for stoichiometry; there are several conversions that we have and use in order to calculate moles (mols) , molecules, atoms, formula units (fu) , and mass (g).

Conversions

• Molecules/particles/molecules/formula units -> moles

• Grams -> moles

• Mole to mole ratio

Avogrado's Number (6.022 x 10²³)

a constant that is used in stoichiometry problems when atoms or molecules are involved

Molecules/atoms/formula units/particles -> moles

Involves Avogrado's number

Mass (in grams) -> moles

the amount of mass given = 1 mole

Periodic Table

We use the periodic table in order to determine how much a compound weighs

Examples: Compound masses

• CH₄ = 16g (1 mole of methane)

• H₂O = 18g (1 mole of water)

• CO₂ = 44g (1 mole of carbon dioxide)

• NH₄ = 18g (1 mole of ammonia)

Explanation

When calculating the mass of a compound or substance one must look at the periodic table.

As you know CH₄ has 1 Carbon atom and 4 Hydrogen atoms. If you look at the periodic table, you will see that Carbon's relative atomic mass is 12 and Hydrogen's relative atomic mass is 1.

Since there is only one carbon atom that is 12 grams, and because there are 4 hydrogen atoms in CH₄ that adds another 4 grams to the compound. Adding the carbon and hydrogens together would mean you are adding the masses as well; therefore your relative molar mass would be 16g.

Mole Ratio

the correlation between the number of reacting particles and utilizes the coefficients in balanced equations