Chemistry Avogadro's Law, Ideal Gas Law, Moles/Stoichiometry

Calculating percent composition

see pages 34-35, 39. You put the amount of one part over the total, and multiply by 100.

Gram-atomic mass/molar mass

the mass, in grams, or 1 mole of an element. Found on Table T

The ideal gas law can be used

to find other physical values of a gas that are not as obvious, such as: gas density (d=mass/volume) gas molar mass (MW=mass/1 mole)

When given the mass in g

use as given mass, and when looking for the number of molecules you use the gram-atomic mass formula, and multiply that answer by 6 * 10^23 molecules.

For some molar mass calculations

you will need to use mole calculations formula found on Table T to convert the given mass and molar mass (which you have to calculate), and put the number of moles into the ideal gas law.

A mole is

6 * 10^23 items = 1 mol

Molar Volume

The molar volume of a gas measured at STP is 22.4 L for 1 mole of any gas. You can solve for it using this proportion attached, or the ideal gas law (PV=nRT) as (1 atm)V=(1)(0.0821)(273)

STP (Table A)

The volumes of gases can be compared at STP when they have the same temperature and pressure

Hydrates

Some ionic compounds incorporate a fixed number of water molecules into their formula unit. Naming hydrates only makes sense when you are dealing with solid reagents. The number of waters is indicated with a multiplier number.

Empirical vs Molecular Formula

The empirical formula represents a simple whole number ration of the number of moles of elements in the compound, while the molecular formula shows the actual number of atoms of each type in a molecule

Moles and Stoichiometry

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Gas Law Problems - Things to remember

1) Temperature must always be in Kelvin 2) If the problem involves a set of initial and final conditions, USE COMBINED GAS LAW 3) If the problem only gives information for one set of conditions, use IDEAL GAS LAW

For Ideal Gases

Go to Chem Gas Phase Quizlet

Avogadro's Ideal Gas Law

Has to do with volume and moles. This law states that the volume of a gas is directly related to the number of moles of gas, and temperature and pressure are constant.

Calculating molar mass

Look at pgs 9 and 17 on the slide for an exception

Review

Pg 10 of notes

To find one mole of an element

go to the periodic table and look at the Atomic Mass

The Ideal Gas Law

is a combination of the combined gas law and Avogadro's. Remember, R= 0.0821 L atm/K mole