CHEMISTRY 103.101 EXAMINATION 4 (CHAPTER 5)

Dr. Alfred N. Amah

April 17, 2002

Name ______ID# ______

This examination consists of five short structured questions each worth 20 points. Carefully read each question and provide the correct response. You must show all your work in the space provided for each question for full credit. Good Luck

  1. Carbon monoxide (CO) may be formed from the improper combustion of carbon with oxygen (O2) according to the following balanced chemical equation:

2C + O2  2CO

a). Calculate the mass of carbon that can be consumed by 160 g of oxygen in this combustion to give carbon monoxide. (Please show your work).

b) Calculate the mass (in grams) of carbon monoxide that can be produced from the above reaction.

  1. Nitric oxide (NO) reacts instantly with oxygen gas to give nitrogen dioxide (NO2), a dark-brown gas:

2NO(g) + O2(g)  2NO2 (g)

a). In one experiment, 0.886 mol of NO is mixed with 0.503 mol of O2. Calculate which of the two reactants is the limiting reagent. Please show your set-up and work in the space provided.

b). Calculate the number of moles of NO2 that can be produced. Show your work and set-up for full credit.

  1. Water can be made in a laboratory from the reaction of hydrogen gas, H2 and oxygen gas, O2 according to the following reaction:

2H2 + O2 2H2O

In one experiment, 2.50 mol of hydrogen gas was allowed to react with 2.00 mol of oxygen gas and 4.50 gram of water was produced. Calculate the % yield of water in this reaction. Please show your work for proper credit. (Hint: calculate the limiting reactant and theoretical yield). { H = 1.0; O = 16.0}

  1. Please balance the following reactions:

a. C3H8 + O2  CO2 + H2O

b. C4H10(g) + O2(g)  CO2(g) + H2O(l)

c. CH4(g) + Cl2(g)  HCl (g) + CHCl3(g)

d.Fe2O3(s) + Al(s)  Al2O3 (s) + Fe(l)

  1. Given the reaction represented by the balanced equation:

2C2H2 + 5O2  4CO2 + 2 H2O

acetylene oxygen water

  1. Calculate the number of grams of water, H2O, produced by burning 26.0 g of acetylene , C2H2 with 160.0 g of O2
  1. If 9.0 gram of water, H2O were produced, calculate the % yield.

c. If a student performed the same reaction in (5) above and got a 90% yield, how much water in grams were produced?