ChemEquationsLabLR/TY Stoichi- ometry Potpourri Final
Chem Eqns 100 Chem Eqns How is bromine written in a chemical equation? Answer Answer
Chem Eqns Chem Eqns 100 Br 2 It is diatomic
Chem Eqns 200 Chem Eqns Write a balanced equation, with phases, for the formation of carbon monoxide from its elements. Answer Answer
Chem Eqns Chem Eqns 200 2C (s) + O 2(g) 2CO (g)
Chem Eqns 300 Chem Eqns To balance a chemical equation, you may change _______ but you may not change ______ Answer Answer
Chem Eqns Chem Eqns 300 To balance a chemical equation, you may change _coefficients_ but may not change _subscripts or formulas_
Chem Eqns 400 Chem Eqns Write a balanced chemical equation for the combustion of heptane, C 7 H 16 Answer All Play!!! Answer
Chem Eqns Chem Eqns 400 Answer 1C 7 H O 2 7CO 2 + 8H 2 O
Chem Eqns 500 Chem Eqns Write the balanced equation, with phases, for the reaction between silver nitrate and copper. AnswerAnswer All Play!!!!
Chem Eqns Chem Eqns 500 Answer 2AgNO 3(aq) + Cu (s) 2 Ag (s) + Cu(NO 3 ) 2(aq)
Lab 100 Lab What observation allows you to determine that a reactant is the Limiting Reactant? Answer Answer
Lab Lab 100 Answer It is gone – used up. It may not always be possible to observe this, for instance if it is in the aqueous phase.
Lab 200 Lab What observation allows you to determine that a reactant is the Excess Reactant? What is the Excess Reactant in most combustions? Explain. Answer
Lab Lab 200 Answer Some of the excess reactant is left over after the reaction stops. Oxygen is the ER in combustions b/c it comes from the air and is unlimited.
Lab Explain why a candle loses mass as it burns. 300 Lab Explain why a candle loses mass as it burns. Answer Answer
Lab Lab 300 Answer Products are CO 2 and H 2 O gases that escape into the air during combustion
Lab 400 Lab In the AgNO 3 Lab, which of the following experimental errors would give a ratio of 1.10 mol Ag/1mol AgNO 3 ? A. Running more than 30 min. B. Insufficient washing/decanting C. Weighing Ag while it is still wet. D. Impure reactants Answer Answer All Play!!
Lab Lab 400 Answer B and C will increase mass of Ag insufficient washing leaves some copper nitrate in with Ag. Weighing wet gives mass of Ag + water A does not have an effect b/c the reaction STOPS when limiting reactant is used up. More time does not give more product after LR is gone. D decreases mass of product
Lab 500 Lab What was the purpose of washing and decanting the silver after the silver nitrate reaction had finished? Answer Answer
Lab Lab 500 Answer To purify the Ag by rinsing away the water soluble product, Cu(NO 3 ) 2.
LR/TY 100 LR/TY What is the molar mass, to 2 decimals, of Cu(NO 2 ) 2 ? Answer Answer
LR/TY LR/TY 100 Answer g/mol
LR/TY 200 LR/TY Write the mole ratio of phosphorus to fluorine in the following equation P 4 + 6F 2 4PF 3 Answer All Play!!!
LR/TY LR/TY 200 1mole P 4 6mol F 2
LR/TY Stoichiometry predicts 2.55 g of Ag product. Data gives the following: empty beaker = g beaker plus Ag = g What is % Yield? 300 LR/TY Stoichiometry predicts 2.55 g of Ag product. Data gives the following: empty beaker = g beaker plus Ag = g What is % Yield? Answer Answer All Play!!!
LR/TY LR/TY 300 Answer % Yield = 2.00g x g = 78.4%
LR/TY List 4 reasons, other than human error, why yield is usually less than 100%. 400 LR/TY List 4 reasons, other than human error, why yield is usually less than 100%. All Play!! Answer Answer
LR/TY LR/TY 400 Answer See your class notes!
LR/TY If 5.00 g of S 8 and g of Cu are combined, what is the theoretical yield of product? 500 LR/TY If 5.00 g of S 8 and g of Cu are combined, what is the theoretical yield of product? 16Cu + S 8 8Cu 2 S Answer Answer
LR/TY LR/TY 500 Answer 5.00 g of S 8 gives mol Cu 2 S g of Cu gives mol Cu 2 S Cu is the Limiting Reactant mol Cu 2 S x g/mol = g Cu 2 S
Stoichiometry 100 Stoichiometry What two types of conversion factors are needed for stoichiometry calculations? Answer Answer
Stoichiometry Stoichiometry 100 Answer Mole Ratio from the balanced equation Molar Mass
Stoichiometry 200 Stoichiometry What part of a balanced equation gives the numerical part of the mole ratio? Answer Answer All Play!!