Problem 1
A 13 gram gascous sample of an unknown hydrocarbon occupies a volume of \(11.2 \mathrm{~L}\) at STP. What is the hydrocarbon? A. \(\mathrm{CH}\) B. \(\mathrm{C}_2 \mathrm{H}_4\) C. \(\mathrm{C}_2 \mathrm{H}_2\) D. \(\mathrm{C}_3 \mathrm{H}_3\)
Problem 3
. Ammonia bums in air to form nitrogen dioxide and water. $$ 4 \mathrm{NH}_3(\mathrm{~g})+7 \mathrm{O}_2(\mathrm{~g}) \rightarrow 4 \mathrm{NO}_2(\mathrm{~g})+6 \mathrm{H}_2 \mathrm{O}(l) $$ If 8 moles of \(\mathrm{NH}_3\) are reacted with 14 moles of \(\mathrm{O}_2\) in a rigid container with an initial pressure of 11 atm, what is the partial pressure of \(\mathrm{NO}_2\) in the container when the reaction runs to completion? (Assume constant temperature.) A. 4 atm B. 6 atm C. 11 atm D. \(12 \mathrm{~atm}\)
Problem 8
A1 STP, otie liter of which of the following grses contains the most molecules? A. \(\mathrm{H}_2\) B. He C. \(\mathrm{N}_2\) D. Each gas contains the same number of molocules at STP.
Problem 12
The reaction below proceeds via the two step mechanism as shosyn. Overall Reaction: \(\quad 2 \mathrm{NO}_2+\mathrm{F}_2 \rightarrow 2 \mathrm{NO}_2 \mathrm{~F}\) Siep 1: \(\quad \mathrm{NO}_2+\mathrm{F}_2 \rightarrow \mathrm{NO}_2 \mathrm{~F}+\mathrm{F}\) Step 2: \(\quad \mathrm{NO}_2+\mathrm{F} \rightarrow \mathrm{NO}_2 \mathrm{~F}\) \(X\) is the rate of step 1 , and \(Y\) is the rate of step 2 . If step \(I\) is much slower than step 2 , then the rate of the overall reaction can be represented by: A. \(X=\) 15\. \(y^{+}\) C. \(X+Y\) D. \(X-Y\)
Problem 15
The conversion of cis-2-butene to trans-2-butene lakes place in a reaction that is first-order with respect to cis-2butene. The conversion was observed in two separate trials under identical conditions except that in the second trial, the concentration of cis-2-butene was doubled. In the second trial: A. the reaction rate will be halved. B. the reaction rate will be doubled. C. the rate constant will be halved. D. the rate constant will be deubled.
Problem 16
When a radioactive isotope undergoes nuclear decay, the concentration of the isotope decreases exponentially with a constant half-life. It can be determined from this that rodionctive decay is a: A. zeroth order reaction. B. first onder reaction. C. second order reaction. D. third order reaction.
Problem 18
. All of the following are tne concerning a reaction at equilibrium EXCEIPT: A. The rate of the forward reaction equals the rate of the reverse reaction. B. There is no change in the concentrations of both the products and the resctants. C. The activation encrgy has reached zero. D. The Gibbs free energy has reached a minimum.
Problem 19
Nitric acid is produced commercially by oxjdation in the Oswald process. The first step of this process is shown below. $$ 4 \mathrm{NH}_3(\mathrm{~g})+5 \mathrm{O}_2(g) \rightleftharpoons 4 \mathrm{NO}(\mathrm{g})+6 \mathrm{H}_1 \mathrm{O}(g) $$ A containce holds 4 moles of gaseous ammonia, 5 moles of gaseous oxygen, 4 moles of gaseous mitric oxide, and 6 moles of water vapor at equilibrium. Whicl of the following would be true if the container were allowed to expand at constant temperature? A. Initially during the expansion the forward reaction rate would be greater than the reverse reaction rate. B. The equilibritim would shift to the left. C. The partial pressuie of oxygen would increase. D. The pressure inside the container would increase.
Problem 21
Which of the following is true concerning a reaction that begins with only reactants and moves to equilibrium? A. The rate of the forward and reverse reactions decreases until cquilibrium is reached. B. The rate of the forward and reverse reactions increases until equilibriam is reached. C. The rate of the forward reaction decreases, and the rate of the reverse reaction increases until equilibrium is reaclyed. D. The rate of the forward reaction increases, and the rare of the reverse reaction decreases until equilibrium is reached.
