Lewis Structures and VSEPR Theory
Stoichiometry
Limiting and Excess Reactant
Percent Yield
Mixed
100
Draw the lewis structure of phosphorus trihydride
100
Based on the following balanced chemical equation, what is the mole ratio for N2 to O2?
N2 (g) + O2 (g) --> 2NO (g)
1:1
100
At the end of a chemical reaction, which reactant is still present in the reaction vessel?
excess
100
What is the equation to calculate percent yield of a certain product?
percent yield = (actual yield)/(theoretical yield) x 100
100
True or false? According to the law of conservation of mass, the mass of reactants is the same as that of the products of a chemical reaction
True
200
What is the electron domain geometry and molecular geometry of hydrogen disulfide?
EDG: tetrahedral
MG: bent
200
First, balance the chemical equation for the combustion of C3H8:
C3H8 (g) + O2 (g) --> CO2 (g) + H2O (g)
What is the mole ratio of O2 to CO2? Write two conversion factors.
(5 mol O2)/(3 mol CO2), (3 mol CO2)/(5 mol O2)
200
How many grams of Co2S3 can be produced from the reaction of 250. g of Co and 250. g of S?
The chemical equation is:
2Co (s) + 3S (s) --> Co2S3 (s)
454 g
200
How is the actual yield determined (in the calculation for percent yield)?
Through experiment
200
What is the sign (+ or -) of delta(H) for endothermic reactions?
positive
300
Specify the following information for a molecule of carbon dioxide:
# bonded pairs:
# lone pairs:
Bond angle:
2 bonded pairs,
0 lone pairs,
180 deg.
300
How many moles of oxygen are needed to react with 0.360 mol of ethanol (C2H6O)?
The chemical equation for this reaction is:
C2H6O (g) + 3O2 (g) --> 2CO2 (g) + 3H2O (g)
1.08 mol
300
If 50.0 g of C3H8 and 150. g of O2 react, the LR is:
The chemical equation is: (unbalanced!)
C3H8 (g) + O2 (g) --> CO2 (g) + H2O (g)
O2
300
When 35.0 g of O2 reacts with sufficient ethane to produce 12.5 g of H2O, what is the percent yield of H2O?
The chemical equation is:
2C2H6 (g) + 7O2 (g) --> 4CO2 (g) + 6H2O (g)
74.0%
300
The limiting reactant is ALWAYS the reactant with the fewest moles
False
400
True or false: the molecular geometry is the same for these two molecules: Draw the lewis structure for each to support your answer
methane (CH4)
PCl5
False
400
How many grams of carbon dioxide are produced when 92.0 g of ethanol (C2H6O) reacts?
The chemical equation is:
C2H6O (g) + 3O2 (g) --> 2CO2 (g) + 3H2O (g)
176 g
400
Consider respiration, one of the most common chemical reactions on earth:
C6H12O6 +6O2 --> 6CO2 + 6H2O + energy
How many moles of carbon dioxide forms when 25 g of glucose reacts with 40 grams of oxygen?
0.83 mol
400
If 23.3 g of galactose reacts to give 26.3 g of CO2, what is the percent yield of CO2?
The chemical equation is:
C6H12O6 (aq) + 6O2 (g) --> 6CO2 (g) + 6H2O (l)
76.9%
400
Where is "heat" placed in a chemical reaction for exothermic reactions? (reactants side or products side)
products side
500
Which molecule has a multiple bond? N2 of F2? Draw the lewis structure for each
N2
500
When 25.0 g of N2 reacts, what is the theoretical yield of NH3 (in grams)?
First, balance the equation:
N2 (g) + H2 (g) --> NH3 (g)
30.4 g
500
Consider respiration, one of the most common chemical reactions on earth:
C6H12O6 +6O2 --> 6CO2 + 6H2O + energy
25 g of glucose reacts with 40 grams of oxygen...how many moles of excess reagent are leftover?
0.42 mol
500
If 25.0 g of O2 reacting with sufficient H2S produces 18.6 g of SO2, what is the percent yield of SO2?
First, balance this equation:
H2S (g) + O2 (g) --> SO2 (g) + H2O (g)
55.7%
500
Is the following reaction endothermic or exothermic?
CaCO3(s) + 556 kJ --> CaO(s) + CO2(g)
endothermic