Balance the following equations. (Chapter 9) a. Sn(s) +

Calculate the average reaction rate expressed in moles H 2 consumed per liter per second.

Calculate the average reaction rate expressed in moles C l 2 consumed per liter per second.

Challenge If the average reaction rate for the reaction, expressed in moles of HCl formed, is 0.0050 mol/Ls, what concentration of HCl would be present after 4.00 s?

Relate collision theory to reaction rate

Explain what the reaction rate indicates about a particular chemical reaction.

Compare the concentrations of the reactants and products during the course of a chemical reaction (assuming no additional reactants are added).

Explain why the average rate of a reaction depends on the length of the time interval over which the rate is measured.

Describe the relationship between activation energy and the rate of a reaction.

Summarize what happens during the brief existence of an activated complex.

Apply collision theory to explain why collisions between two reacting particles do not always result in the formation of a product.

Interpret how the speed of a chemical reaction is related to the spontaneity of the reaction.

Calculate the average rate of a reaction between hypothetical molecules A and B if the concentration of A changes from 1.00M to 0.50M in 2.00 s.

Explain why magnesium metal reacts with hydrochloric acid (HCl) at a faster rate than iron does.

Explain how collision theory accounts for the effect of concentration on reaction rate.

Explain the difference between a catalyst and an inhibitor

Describe the effect on the rate of a reaction if one of the reactants is ground to a powder rather than used as a single chunk.

Infer If increasing the temperature of a reaction by 10 K approximately doubles the reaction rate, what would be the effect of increasing the temperature by 20 K?

Research how catalysts are used in industry, in agriculture, or in the treatment of contaminated soil, waste, or water. Write a short report summarizing your findings about the role of a catalyst in one of these applications.

Write the rate law for the reaction aA bB if the reaction is third order in A. [B] is not part of the rate law

The rate law for the reaction 2NO(g) + O 2(g) 2N O 2(g) is first order in O 2 and third order overall. What is the rate law for the reaction?

Given the experimental data below, use the method of initial rates to determine the rate law for the reaction aA + bB products. (Hint: Any number to the zero power equals one. For example, (0.22) 0 = 1 and (55.6) 0 = 1.) Practice Problem 21 Experimental Data Trial Initial [A](M ) Initial [B](M ) Initial Rate (mol/(Ls)) 1 0.100 0.100 2.00 1 0 -3 2 0.200 0.100 2.00 1 0 -3 3 0.200 0.200 4.00 1 0 -3

Challenge The rate law for the reaction C H 3CHO(g) C H 4(g) + CO(g) is Rate = k [C H 3CHO ] 2. Use this information to fill in the missing experimental data below. Practice Problem 22 Experimental Data Trial Initial [C H 3CHO](M ) Initial Rate (mol/(Ls)) 1 2.00 1 0 -3 2.70 1 0 -11 2 4.00 1 0 -3 10.8 1 0 -11 3 8.00 1 0 -3

Explain what the rate law for a chemical reaction tells you about the reaction.

Apply the rate-law equations to show the difference between a first-order reaction with a single reactant and a second-order reaction with a single reactant.

Explain the function of the specific rate constant in a rate-law equation.

Explain Under what circumstance is the specific rate constant (k), not a constant. What does the size of k indicate about the rate of a reaction?

Suggest a reason why, when given the rate of a chemical reaction, it is important to know that the reaction rate is an average reaction rate

Explain how the exponents in the rate equation for a chemical reaction relate to the coefficients in the chemical equation.

Determine the overall reaction order for a reaction between A and B for which the rate law is rate = k[A ] 2 [B ] 2 .

Design an Experiment Explain how you would design an experiment to determine the rate law for the general reaction aA + bB products using the method of initial rates.

Use the rate law in Example Problem 16.2 and the concentrations given in Practice Problems 31 and 32 to calculate the instantaneous rate for the reaction between NO and H 2.

Use the rate law in Example Problem 16.2 and the concentrations given in Practice Problems 31 and 32 to calculate the instantaneous rate for the reaction between NO and H 2.

Challenge Calculate [NO] for the reaction in Example Problem 16.2 if the rate is 9.00 1 0 -5 mol/(L s) and [ H 2] is 0.00300M.

Compare and contrast an elementary chemical reaction with a complex chemical reaction.

Explain how the rate law for a chemical reaction is used to determine the instantaneous rate of the reaction.

Define a reaction mechanism and an intermediate

Distinguish between an intermediate and an activated complex.

Relate the size of the activation energy of an elementary step in a complex reaction to the rate of that step

Calculate A reaction between A and B to form AB is first order in A and first order in B. The rate constant, k, equals 0.500 mol/(L s). What is the rate of the reaction when [A] = 2.00 1 0 -2M and [B] = 1.50 1 0 -2M?

What happens to the concentrations of the reactants and products during the course of a chemical reaction?

Explain what is meant by the average rate of a reaction.

How would you express the rate of the chemical reaction A B based on the concentration of Reactant A? How would that rate compare with the reaction rate based on the Product B?

What is the role of the activated complex in a chemical reaction?

Suppose two molecules that can react collide. Under what circumstances do the colliding molecules not react?

Figure 16.21 is an energy level diagram for a reaction. Match the appropriate number with the quantity it represents. a. reactants b. activated complex c. products d. activation energy

If A B is exothermic, how does the activation energy for the forward reaction compare with the activation energy for the reverse reaction (A B)?

In the gas-phase reaction, I 2 + C l 2 2ICl, [ I 2 ] changes from 0.400M at 0.00 min to 0.300M at 4.00 min. Calculate the average reaction rate in moles of I 2 consumed per liter per minute.

In a reaction Mg(s) + 2HCl(aq) H 2 (g) + MgC l 2 (aq), 6.00 g of Mg was present at 0.00 min. After 3.00 min, 4.50 g of Mg remained. Express the average rate as mol Mg consumed/min.

If a chemical reaction occurs at the rate of 2.25 1 0 -2 moles per liter per second at 322 K, what is the rate expressed in moles per liter per minute?

What role does the reactivity of the reactants play in determining the rate of a chemical reaction?

In general, what is the relationship between reaction rate and reactant concentration?

Apply collision theory to explain why increasing the concentration of a reactant usually increases the reaction rate.

Explain why a crushed solid reacts with a gas more quickly than a large chunk of the same solid.

Food Preservation Apply collision theory to explain why foods usually spoil more slowly when refrigerated than at room temperature.

Apply collision theory to explain why powdered zinc reacts to form hydrogen gas faster than large pieces of zinc when both are placed in hydrochloric acid solution.

Hydrogen peroxide decomposes to water and oxygen gas more rapidly when manganese dioxide is added. The manganese dioxide is not consumed in the reaction. Explain the role of the manganese dioxide.

Examine Figure 16.22, which relates relative reaction rate and temperature. Approximately how does the reaction rate change for each increase of 10 K?

Suppose that a large volume of 3% hydrogen peroxide decomposes to produce 12 mL of oxygen gas in 100 s at 298 K. Estimate how much oxygen gas would be produced by an identical solution in 100 s at 308 K.

Using the information in Question 58, estimate how much oxygen gas would be produced in an identical solution in 100 seconds at 318 K. Estimate the time needed to produce 12 mL of oxygen gas at 288 K.

In the method of initial rates used to determine the rate law for a chemical reaction, what is the significance of the word initial?

Why must the rate law for a chemical reaction be based on experimental evidence rather than the balanced equation for the reaction?

Assume that the rate law for a generic chemical reaction is rate = [A][B ] 3 . What is the reaction order in A, the reaction order in B, and the overall reaction order?

Consider the generic chemical reaction: A + B AB. Based on experimental data, the reaction is second order in Reactant A. If the concentration of A is halved, and all other conditions remain unchanged, how does the reaction rate change?

The instantaneous rate data in Table 16.3 were obtained for the reaction H 2 (g) + 2NO(g) H 2 O(g) + N 2 O(g) at a given temperature and concentration of NO. How does the instantaneous rate of this reaction change as the initial concentration of H 2 is changed? Based on the data, is [ H 2 ] part of the rate law? Explain. Table 16.3 Reaction Between H 2(g) and NO(g) [ H 2] (mol/L) Instantaneous Rate (mol/Ls) 0.18 6.00 1 0 -3 0.32 1.07 1 0 -2 0.58 1.93 1 0 -2

Suppose that a generic chemical reaction has the rate law of rate = [A ] 2 [B ] 3 and that the reaction rate under a given set of conditions is 4.5 1 0 -4 mol/(L min). If the concentrations of both A and B are doubled and all other reaction conditions remain constant, how will the reaction rate change?

The experimental data in Table 16.4 were obtained for the decomposition of azomethane (C H 3 N 2 C H 3 ) at a particular temperature according to the equation C H 3 N 2 C H 3 (g) C 2 H 6 (g) + N 2 (g). Use the data to determine the reactions experimental rate law. Table 16.4 Decomposition of Azomethane Experiment Number Initial [C H 3N 2C H 3] Initial Reaction Rate 1 0.012M 2.5 1 0 -6 mol/(Ls) 2 0.024M 5.0 1 0 -6 mol/(Ls)

Use the data in Table 16.4 to calculate the value of the specific rate constant, k.

At the same temperature, predict the reaction rate when the initial concentration of C H 3 N 2 C H 3 is 0.048M. Use the data in Table 16.4.

Distinguish between a complex reaction, a reaction mechanism, and an elementary step.

Suppose that a chemical reaction takes place in a twostep mechanism. Step 1 (fast) A + B C Step 2 (slow) C + D E Which step in the reaction mechanism is the ratedetermining step? Explain.

In the reaction described in Question 70, what are Steps 1 and 2 called? What is substance C called?

In Figure 16.23, identify each of the labels 1, 2, 3, 4, 5, and 6 as one of the following: activated complex, intermediate, reactants, or products.

Dinitrogen pentoxide decomposes in chloroform at a rate of 2.48 1 0 -4 mol/(L min) at a particular temperature according to the equation 2 N 2 O 5 4N O 2 + O 2 . The reaction is first order in N 2 O 5 . Given an initial concentration 0.400 mol/L, what is the rate constant for the reaction? What is the approximate [ N 2 O 5 ] after the reaction proceeds for 1.30 h?

Radioactive decay is first order in the decaying isotope. For example, strontium-90 contained in fallout from nuclear explosions decays to yttrium-90 and a beta particle. Write the rate law for the decay of strontium-90.

Evaluate the validity of this statement: You can determine the rate law for a chemical reaction by examining the mole ratio of reactants in the balanced equation. Explain your answer.

The concentration of Reactant A decreases from 0.400 mol/L at 0.00 min to 0.384 mol/L at 4.00 min. Calculate the average reaction rate during this time period. Express the rate in mol/(L min).

The mass of a sample of magnesium is obtained and the sample is placed in a container of hydrochloric acid. A chemical reaction occurs according to the equation Mg(s) + 2HCl(aq) H 2 (g) + MgC l 2 (aq). Use the data in Table 16.5 to calculate the volume of hydrogen gas produced at STP during the 3.00-min reaction? (Hint: 1 mol of an ideal gas occupies 22.4 L at STP) Table 16.5 Reaction of Magnesium and Hydrochloric Acid Time (min) Mass of Magnesium (g) Volume of Hydrogen at STP (L) 0.00 6.00 0.00 3.00 4.50 ?

If the concentration of a reaction product increases from 0.0882 mol/L to 0.1446 mol/L in 12.0 minutes, what is the average reaction rate during the time interval?

A two-step mechanism has been proposed for the decomposition of nitryl chloride (N O 2 CL). Step 1: N O 2 Cl(g) N O 2 (g) + Cl(g) Step 2: N O 2 Cl(g) + Cl(g) N O 2 (g) + C l 2 (g) What is the overall reaction? Identify any intermediates in the reaction sequence, and explain why they are called intermediates.

Compare and contrast the reaction energy diagrams for the overall decomposition of nitryl chloride by the mechanism in Problem 79 under two assumptions: Athat the first step is slower; Bthat the second step is slower.

Automobile Engine The following reaction takes place in an automobiles engine and exhaust system. NO 2(g) + CO(g) NO(g) + CO 2(g) The reactions rate law at a particular temperature is Rate = 0.50 L/(mol s)[N O 2 ] 2 . What is the reactions initial, instantaneous rate when [N O 2 ] = 0.0048 mol/L?

The concentrations in a chemical reaction are expressed in moles per liter and time is expressed in seconds. If the overall rate law is third-order, what are the units for the rate and the rate constant?

Visualize the reaction energy diagram for a one-step, endothermic chemical reaction. Compare the heights of the activation energies for the forward and reverse reactions.

Differentiate between the shaded areas in Figure 16.24 at temperatures T 1 and T 2 on the basis of the number of collisions per unit time that might occur with energy equal to or greater than the activation energy.

Apply the method of initial rates to determine the order of a chemical reaction with respect to Reactant X. Create a set of hypothetical experimental data that would lead you to conclude that the reaction is second order in X.

Formulate a rationale to explain how a complex chemical reaction might have more than one rate-determining elementary step.

Construct a diagram that shows all of the possible collision combinations between two molecules of Reactant A and two molecules of Reactant B. Now, increase the number of molecules of A from two to four and sketch each possible A-B collision combination. By what factor did the number of collision combinations increase? What does this tell you about the reaction rate?

Apply collision theory to explain two reasons why increasing the temperature of a reaction by 10 K often doubles the reaction rate

Create a table of concentrations, starting with 0.100M concentrations of all reactants, that you would propose in order to establish the rate law for the reaction aA + bB + cD products using the method of initial rates.

Hydrocarbons Heating cyclopropane ( C 3 H 6 ) converts it to propene (C H 2=CHC H 3 ). The rate law is first order in cyclopropane. If the rate constant at a particular temperature is 6.22 1 0 -4 s 1 and the concentration of cyclopropane is held at 0.0300 mol/L, what mass of propene is produced in 10.0 min in a volume of 2.50 L?

For the following categories of elements, state the possible number(s) of electrons in their outermost orbitals in the ground state? (Chapter 5) a. p-block elements b. nitrogen-group elements c. d-block elements d. noble-gas elements e. s-block elements

Classify each of the following elements as a metal, nonmetal, or metalloid. (Chapter 6) a. molybdenum b. bromine c. arsenic d. neon e. cerium

Using Figure 16.25, determine how many sigma and pi bonds are contained in a single ethene molecule. (Chapter 8)

Balance the following equations. (Chapter 9) a. Sn(s) + NaOH(aq) N a 2 Sn O 2 + H 2 b. C 8 H 18 (l) + O 2 (g) C O 2 (g) + H 2 O(l) c. Al(s) + H 2 S O 4 (aq) A l 2 (S O 4 ) 3 (aq) + H 2 (g)

What mass of iron(III) chloride is needed to prepare 1.00 L of a 0.255M solution? (Chapter 14)

What information must you know to calculate the boiling point elevation of a solution of hexane in benzene? (Chapter 14)

H for a reaction is negative. Compare the energy of the products and the reactants. Is the reaction endothermic or exothermic? (Chapter 15)

Pharmaceuticals Imagine that your nation is experiencing an influenza epidemic. Fortunately, scientists have recently discovered a new catalyst that increases the rate of production of an effective flu medicine. Write a newspaper article describing how the catalyst works. Include a reaction energy diagram and an explanation detailing the importance of the discovery

Lawn Care Write an advertisement that explains that Company As fertilizer works better than Company Bs fertilizer because it has smaller sized granules. Include applicable diagrams.

What is the average rate of the reaction in the first 22.3 s expressed in moles of phenolphthalein consumed per liter per second?

What is the average rate of the reaction as the phenolphthalein concentration decreases from 0.00050M to 0.00015M?

The rate law is rate = k[phenolphthalein]. If the rate constant for the reaction is 1.0 1 0 -2 s -1 , what is the instantaneous rate of reaction when the concentration of phenolphthalein is 0.0025M?