University:
Emory University
Course:
CHEM 141 | General Chemistry I
Academic year:

2021
Views:

162

Pages:

4
Author:

Aiden F.

Lecture 3.04.21 Chemicals Rxns and Quantities Chemical reactions occur everywhere ↳ Digesting food Gasoline burning. Air conditioning Hair is bleached, or dyed or straightened Grape juice ferments to produce wine PHYSICAL CHANGE OF WATER INTO ICE CHEMICAL CHANGE OF WATER INTO HYDROGEN PEROXIDE Physical change the appearance of the substance is altered, but NOT its composition Chemical change the reacting substances change into new substances that have different formulas and different properties. 18th century Antoine Lavoisier: reaction between tin and air and found the mass of the substances unchanged. Joseph Proust: studied the reaction of hydrogen and oxygen. To produce water. He found that I g of It would always react with 8 g of O to produce 99 of water. Law of conservation of Mass Reactants Products Chemical Equations: In chemical reactions, atoms are neither created or destroyed. CHA+ O2 CO2 + H2O change to: CH4 + 202 CO2 + 2H2O Methane oxygen carbon dioxide water Balancing Equations: The principle that lies at the heart of the balancing process is that atoms are conserved in a chemical reaction. Lecture 3.09.21 Molar Mass Number of grams the atomic mass Molar Mass of oxygen: 16.09g Molar Mass of Hydrogen: 1.008 g Molar Mass of Silver 107.99 Molar Mass of a compound S02 I mol S = 1(32.06) = 32.06 32.069 2 mol O2C16.00)=32.00g 5 32.06 + 32.00 = 64.069 The molar mass of SO2 is 64.06 Molar Mass of C6H1206 - C: 6 mol C x 12.01 = 72.069 H: 12 mol H x 1.008 = 12.096 g 0:6 mol O x 16.00 = 96.00g 572.0bg + 12.096g+ 96.00g = 180.1569 180.169 Mg(NO3)2 - Mg: I mol Mg x 24.3 g = 24.39 N. 2 mol Nx 14.0g = 28.09. 06 mol o x 16.0g = 96.09 4 24.3 + 28.0 + 96.0 = 148.39 Exothermic: Heat released. Heat is on product side ↳ Ex: Cha (g) + 202 (g) → CO2(g) + 2H2O(g) + 213 kcal heat released Endothermic Heat absorbed. Heat is on reactant side ↳ Ex: H2(g) +12(g) + 12 kcal → 2HI (9) heat absorbed Chemical Equations (Mole - Mole Factors) Fe (s) + S (5) Fe2 S3 (S) - 2Fe (s) + 35(s) Fe₂S3 (5) - 2 mol of Fe reacts with 3 mol of S produces Imol of Fez Sz (5) Energy Will make the world a better place: 1. New biodegradable plastics 2. Ozone layer chemicals Types of energy - Potential energy is stored energy kinetic energy is the energy of motion Thermal energy is commonly known as heat Radient energy (solar energy) from the sun The energy given off is usually in the form of thermal energy .Units: - SI unit is the joule (j) Calorie (cal) is also a unit of energy. I cal = 4.184 J Lexact) - I kcal = 1,000 cal Example: convert 9.5 kJ to cal 4.5 KJX1000 J I cal = 1075 cal IkJ 4.184 J Heat always flows from a substance with higher temperature to a substance with a lower temperature . Temperature Conversion: - From Celsius to Fahrenheit TF = 1.8 (Tc) +32° - From Celsius to kelvin CK) Tk Tc + 273" Liquid Nitrogen, is often used as a coolent for low temperature experiments has a boiling point of 77k. What is the temperature on the Fahrenheit scale? Tc= Tk - 273° 77-273-196.C converting to Fahrenheit TF = 1.8 (Tc) + 32° = 1.8 (-196) + 32 = - 321°F