120 likes | 129 Views
Welcome back, maggots…. Homework 8: posted and due this Friday. I’m ready for a break. Practicing…clickers and not clickers. C 3 H 8 + 5O 2 -------- 3CO 2 + 4H 2 O 44 32 44 18 g/mol . f ) weight to count
E N D
Welcome back, maggots…. Homework 8: posted and due this Friday I’m ready for a break
C3H8 + 5O2--------3CO2+ 4H2O 44 32 44 18 g/mol f) weight to count How many molecules of CO2form along with 1.592 g H2O ? =4*1022
C3H8 + 5O2--------3CO2 + 4H2O (BOOM) 44 32 44 18 g/mol How many molecules of O2 are needed to burn 0.29333 g C3H8? (1 mol count =6*1023) (wtcount) • 2*1022 • 4*1021 • 1.76*1023 • 4*1021
C3H8 + 5O2--------3CO2 + 4H2O (BOOM) 44 32 44 18 g/mol molcount How many molecules of CO2form along with 0.0666 mol of H2O ? (1 mol count=6*1023) 3*1022 CO2 molecules
C3H8 + 5O2--------3CO2 + 4H2O (BOOM) 44 32 44 18 g/mol Mol count: How many molecules of O2does it take to form 0.020 moles of CO2 in the reaction above? (1 mol count=6*1023) • 1.2*1022 • 7.2*1021 • 1.0*1022 • 2.0*1022
The mole road trip itinerary so far now: • % composition problems and combustion analysis (pp. 94-103) • Reaction balancing (pp. 105-108) • Reaction stoichiometry predictions, limiting yields and % yields ( pp. 108-123)
Limiting yield and % yield calculations are the last stop on the mole bus trip
A non-chemical example of a `limiting’ yield problem You have gotten lost on the Ad Dahna desert –largest desert on the Saudi peninisula. To avoid perishing you must reach the nearest oasis which is 100 km away. You can walk at maximum 10 km/ day. You need to consume at least 2 liters of water and ½ kg of food per dayto walk that distance. You have in your pack: • 16 liters of water • 5 kg of food • Broken cell phone What’s the maximum distance you can expect to travel ??
Food Calculation 5 kg food = 10 days ½ kg/day =>10 days * 10 km = 100 km day
Water Calculation 16 liters = 8 days 2 liters/day • 8 days * 10 km = 80 km day The winner is….always the smaller one… it limits.