University:
Ontario Tech University
Course:
CHEM1010U | Chemistry I
Academic year:

2024
Views:

315

Pages:

4
Author:

Avneet S.

**Chemistry Lecture #7-3** Quizzes are always one question. **Atomic Mass = (Cu63)(% abundance) + (Cu65)(% abundance)** Let x = % abundance of Cu63 y = % abundance of Cu65 x + y = 1 x = 1 - y Sub into eq. for x Atomic Mass = ((62.9296)(1-y)) + ((64.9278)(y)) = 62.9296 - 62.9296y + 64.9278y = 62.9296 + 1.9982y -62.9296 ------- 31.49 = 1.9982y 31.49 / 1.9982 = y y = 15.76 Atomic Mass = ((62.9296)(x)) + ((64.9278)(y)) = 62.9296x + 64.9278(15.76) = 62.9296x + 1024.458 = 32.49 **Mol is used to count what we can't see** A + B -> AB # of atoms/molecules # of reactions based on # of collisions # of collisions 1 x 10^-3 g x 1 amu / 1.66x10^-24 g = 2 C atoms 12.01 amu 1 mol = 6.02 x 10^23 = 1 amu 1 amu = 1.66 x 10^-24 g **Molecular mass = sum of all components** C₂H₄ = 4 atoms C x 2 = (12.011) x 2 = 24.022 H x 4 = (1.008) x 4 = 4.032 28.054 amu 1 mol of anything will have the same mass as the components molecular/formula mass, just need to convert units. 1 mol Helium = 4 g/mol 1 mol Copper = 63.546 g/mol 1 mol Sulfur = 32.065 g/mol 1 mol Mercury = 200.59 g/mol 3 mols H₂ -> How many molecules of H₂? 6.02 x 10^23 molecules -> 1 mol 3 mol x 6.02 x 10^23 molecules/mol = 1.8 x 10^24 molecules of H₂ How many hydrogen atoms are in 3 mols of H₂? 1.8 x 10^24 molecules of H₂ x 2 H atoms/1 H₂ molecule = 3.6 x 10^24 atoms of H **Common Calculations** **By Avogadro's #** Atoms <-> Moles <-> Molar Mass ↑ ↑ ↑ Mole Mole Mole ↓ ↓ ↓ x by Avogadro's # **When reactants react, the properties of the product change.** ex. Can't ingest Na or Cl, can eat as much NaCl as we want, it's salt! **Chemical Bonding** Only electrons are interacting. **Metal + Non-metal = Ionic Bond** Na 11p+ → Na⁺ 11p+ 11e- → 10e- Cation (+) charge Cl 17p+ → Cl⁻ 18e- 17e- → 18e- Anion (-) charge