The Mole

Stringer, S. C. Morgan Park High School
881-5050

Objectives: Resolution of Problems: The role of a unifying hypothesis (law) and the reasoning process leading to Avogadro's hypothesis. Application of Hypothesis: Diatomic and monoatomic gaseous elements. Avogadro's hypothsis. Determination of molecular weights, atomic weights, etc. Fundamental Skills: Solving problems by use of the gas constants: D(gas) = g mol wt(g)/22.4 l g mol wt(g) = D(gas) * 22.4 l D(gas) = (g/ml)*(1000ml/l) Topic Statement: The data below will apply to Avogadro's hypothesis. This exercise preceded the review of the chapter on the gas laws: Boyle's, Charles', Gay-Lussac's, indicating similarities in the physical behavior of gases. The question of whether gases display any similarities in chemical behavior may then be raised. Discussion of the experimental findings of Gay-Lussac and Proust leads to Gay-Lussac's Law. Avogadro's hypothesis may then be used to explain Gay-Lussac's Law, and the inconsistency with Dalton's Theory may be resolved. Also, consider the historical treatment and significance as in the basic chapter. The diagram of the mole concept and a work sheet follows below: divide by 22.4 l -->| M |--> multiply by GAW/GMW volume (l) <---------------| O |----------------------> mass (grams) multiply by 22.4 l <--| L |<-- divide by GAW/GMW | E | divide by 6.02 * 1023 -->| |--> multiply by 6.02 * 1023 | V number of particles Diatomic elements: Define:
Br, I, N, Cl, H, O, F Density = M/unit volume
Volume = L * W * H
Liquids = cylinder (3l)
GAW = atoms Gas = displacement
GMW = molecules Weight = grams
D = M/V
/--- mass at 1 mole GAW/m wt.
MOLE -------<---- 6.02 * 1023 particles
\--- at STP vol of 1 mole of gas = 22.4 l
Substance Density Volume of 1 mole 1. Mercury | 13.55 g/cm3 |
2. Iron | 7.85 g/cm3 |
3. Ethanol (C2H5OH) | 0.80 g/ml |
4. Propanol (C3H8OH) | 0.78 g/ml |
5. Carbon tetrachloride | 1.59 g/ml |

etc.

Chemistry all of these contain 1 mole SUBSTANCE NUMBER OF MOLECULES FORMULA MASS(g) ML ESTIMATE VOL. Copper 8.92 | | | | 63.5/8.92 = Aluminum 2.70| | | | 27.0/27.0 = 10.0 Iron 7.86 | | | | 55.8/7.86 = Lead 11.34 | | | | Zinc 7.14 | | | | Tin 5.75 | | | | etc. | | | |