# chemical equations, oxidation/redox, chemistry homework help

1. Consider the following unbalanced redox reaction: Cr2O7^2- (aq) + NO2- (aq) —> Cr^3+ (aq) + NO3-(aq). What is the oxidizing agent in the reaction?
a) Cr2O72-
b) NO2-
c) Cr3+
d)NO3-
2. Which equivalence factor set should you use to convert from 4.23×10 ^12 atoms of Ca to grams of Ca?
a) (1 mol Ca/6.02×10^23 atoms Ca) (40.08g Ca/1 mol Ca)
b) (1 mol Ca/4.23 x 10^12 atoms Ca) (40.08g Ca/1mol Ca)
c) (4.23 x 10^12 atoms Ca/1 mol Ca) (1 mol Ca/40.08 g Ca)
d) (4.23 x 10^12 atoms Ca/ 6.02 x 10^23 atoms Ca) (40.08 g Ca)
3. Calculate the change in boiling point when 0.402 moles of sodium chloride are added to ).200 Kilograms of water. Kf=1.86 degrees C/m; Kb = 0.512 degrees C/m
a) -2.1 C
b) 2.1 C
c) -7.5 C
d) 7.5 C
4. Given the following chemical equation, if 58 grams of aluminum reacts wit excess chlorine gas and was found to produce 203 grams of aluminum chloride, what is the percent yield for this reaction? 2Al + 3 Cl^2 –> 2AlCl3?
a) 35%
b) 24%
c)71%
d)68%
5. Consider the following unbalanced redox reaction: MnO4- (aq) + SbH3 (aq) —> MnO2 (s) + Sb(s). What is the reducing agent?
a) MnO4-
b) SbH3
c) MnO2
d)Sb
6. Given 2.91 moles of a gas in a 500ml container, if the temperature is found to be 31 degrees C, what is the pressure of the gas? (the ideal gas constant is 0.0821 L x atm/mol x k)
a) 1.45 x 10^2 atm
b) 1.48 x 10^1 atm
c) 1.45 x 10^-1 atm
d) 1.45 x 10^1 atm
7. Which equivalence factor should you use to convert from 4.28 x 10^19 molecules of 02 to moles of 02?
a) (1 mol O2 / 4.28 x 10^19 molecules 0)
b) (4.28 x 10^19 molecules 02 / 1 mol O2)
c) (1mol O2/ 6.02 x 10^23 molecules O2)
d) (6.02 x 10^23 molecules O2 / 1 mol O2)
8. Given 2.4 liters of a gas at 25 degrees Celsius and at 782 torr, how many moles of a gas are present? (Ideal gas constant is 0.0821 L x atm?mol x k and 1 atm= 760 torr)
a) 1.01 x 10^-1 moles
b) 9.14 x 10 ^2 moles
c) 7.70 x 10^1 moles
d) 1.20 x 10^0 moles

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