Chemistry 11 : Mole Conversion Factors

The mole -   A unit that represents 6.02 * 10^23 Particles -   1 mole of Na atoms = 6.02* 10^23 atoms -   6.02*10^23 is called Avogadro’s number (N_A) -   This number is chosen because the number of atoms has a mass in grams that equals the average atomic mass of a single atom in atomic mass units Mass of 1 atom of Ba = 137.33U Mass of 1 Mole of Ba = 137.33g Mass of 6.02*10^23 atoms of Ba = 137.33g

⇒  Symbol for number of moles -> n ⇒   Unit for number of moles -> mol

-   For atomics -   The symbol for the number of atoms is N with a subscript of the atomic symbol of the element -   Avoogadro’s number is really a conversation factor that allows converting between moles and the number of atoms. N_a = 6.02 * 10^23 atoms / 1 mol Examples : How many atoms are there in 0.5mol of Aluminum?

N_A1 = 0.5mol * (6.02*10^23) atoms / 1mol = 3.01*10^23 atoms

How many moles of sulfur are there in a sample of one million sulfur atoms

N_s = 1.00*10^6 atoms * 1mol / 6.02*10^23 atoms = 1.66*10^18mol

Using conversion factors -   conversion factors convert one unit to another using a ratio that has equal amounts in the numerator and denominator in different units. ⇒  In the numerator -> desired units ⇒  In the denominator -> given units

1000m/1km,  1h/60min ,  12cupcake/1 dozen

Conversion factors can be used together ⇒  Example how many seconds are there in a year (365d) T = 1yr D = 365 H = 24 M = 60 S = 60