Presentation on theme: "Stoichiometry Review Guide. What is stoichiometry?"— Presentation transcript:
Stoichiometry Review Guide
What is stoichiometry?
Multiple Choice In stoichiometry, chemists are mainly concerned with A. the types of bonds found in compounds. B. mass relationships in chemical reactions. C. energy changes occurring in chemical reactions. D. the speed with which chemical reactions occur.
Name 2 ways we have used stoichiometry.
What do the coefficients in a chemical equation tell you?
Assume ideal stoichiometry in the reaction: CH 4 + 2O 2 CO 2 + 2H 2 O If you know the mass of CH 4, you can calculate A. only the mass of CO 2 produced. B. only the mass of O 2 reacting. C. only the mass of CO 2 + H 2 O produced. D. the mass of O 2 reacting & CO 2 + H 2 O produced. Multiple Choice
Which properties must be the same on both sides of a chemical equation?
Which properties don’t have to be the same on both sides of a chemical equation?
2C 2 H 6 + 7O 2 4H 2 O + 6CO 2 Write 3 mole ratios
2C 2 H 6 + 7O 2 4H 2 O + 6CO 2 “For every ___ moles of oxygen and ___ moles of ethane that react, ___ moles of carbon dioxide and ___ moles of water are formed.”
Multiple Choice Which mole ratio for the equation 6Li + N 2 2Li 3 N is incorrect? A. C. B. D. 1 mol N 2 6 mol Li 2 mol N 2 2 mol Li 3 N 1 mol N 2 6 mol Li 2 mol Li 3 N 6 mol Li
2C 2 H 6 + 7O 2 4H 2 O + 6CO 2 Calculate in your head how many moles of carbon dioxide are formed if you begin with 8 mols of ethane.
What is a limiting reactant?
Multiple Choice For the reaction below, how many moles of N 2 are required to produce 18 mol NH 3 ? N 2 + 3H 2 2NH 3 A. 4.5 C. 18 B. 9.0 D. 36
What is an excess reactant?
What is the Limiting Reactant? 2C 2 H 6 + 7O 2 4H 2 O + 6CO 2 7.49 mol 24.6 mol
Multiple Choice What mass of NaCl can be produced by the reaction of 0.75 mol Cl 2 ? 2Na + Cl 2 2NaCl A. 0.75 g C. 44 g B. 1.5 g D. 88 g
Why is the LR not necessarily the reactant with the least amount of moles?
Multiple Choice What mass of CO 2 can be produced from 25.0 g CaCO 3 given the decomposition reaction CaCO 3 CaO + CO 2 A. 11.0 g C. 25.0 g B. 22.0 g D. 56.0 g
How many moles of each product can be formed? 2C 2 H 6 + 7O 2 4H 2 O + 6CO 2 7.49 mol 24.6 mol
Multiple Choice If a chemical reaction involving substances A and B stops when B is completely used up, then B is referred to as the A. excess reactant. B. primary reactant. C. limiting reactant. D. primary product.
How many grams of water can be formed? 2C 2 H 6 + 7O 2 4H 2 O + 6CO 2 7.49 mol 24.6 mol
Multiple Choice If a chemist calculates the maximum amount of product that could be obtained in a chemical reaction, he or she is calculating the A. percentage yield. B. mole ratio. C. theoretical yield. D. actual yield.
How many moles excess reactant remain after the reaction? 2C 2 H 6 + 7O 2 4H 2 O + 6CO 2 7.49 mol 24.6 mol
Short Answer What data are necessary to calculate the percentage yield of a reaction?
Extended Response A student makes a compound in the laboratory and reports an actual yield of 120%. Is this result possible? Assuming that all masses were measured correctly, give an explanation.
Extended Response Benzene, C 6 H 6, and hydrogen bromide, HBr, as shown below. When 40.0 g of benzene are reacted with 95.0 g of bromine, 65.0 g of bromobenzene is produc with bromine, Br 2, to produce bromobenzene, C 6 H 5 Br C 6 H 6 + Br 2 C 6 H 5 Br + HBr a. Which compound is the limiting reactant? b. What is the theoretical yield of bromobenzene? c. What is the reactant in excess, and how much remains after the reaction is completed? d. What is the percentage yield?