Chemistry B
Which expression defines molarity? #moles / Liter (solvent) #mole solute / #mole solution #moles / Liter solution none of these
#moles / Liter solution
Consider the reaction: 2Al(s) + Fe2O3(s) Al2O3(s) + 2Fe(s) The Hf Fe2O3(s) = -824.3 kJ/mole. The Hf for Al2O3(s) = -1675.7 kJ/mole. Finish the equation. Hrxn = [(1)(____________kJ/mole) + (2)(__________kJ/mole)] - [(1)(______________kJ/mole) + (2)(__________kJ/mole)]
-1675.7, 0, -824.3, 0.
Determine the value for the following reaction. N2(g) + 3H2(g) → 2NH3(g)+ 22,000 cal ΔH = _____ 22,000 kcal -22,000 kcal 22 kcal -22 kcal
-22 kcal
In the important industrial process for producing ammonia (the Haber Process), the overall reaction is: N2(g) + 3H2(g) → 2NH3(g) + 100.4 kJ A yield of NH3 of approximately 98% can be obtained at 200°C and 1,000 atmospheres of pressure. What is the ΔH in kJ of heat per mole of NH3(g) formed? 50.2 kJ -50.2 kJ 100.4 kJ -100.4 kJ
-50.2 kJ
How many kilojoules are associated with the formation of 2 moles of HBr(g)?
-73
A reaction has the following values. Calculate ΔG. ΔH = -85.5 kJ/mole ΔS = 0.133 kJ/mole.K) Temperature = 110°C -35 kJ -64 kJ -86 kJ -136 kJ
-86 kJ
All elements have a ΔHf of __________ kJ/mole at standard temperature and pressure.
0
If 10.0 mL of the solution on the right are withdrawn from the 100 mL beaker and diluted again in a similar manner, what is the new concentration?
0.00050
When 10.0 mL of the 0.050 M solution are diluted to 100 mL as shown, what is the new concentration?
0.0050
If water is added to 50 mL of a 0.04 M solution so that it fills a 200 mL beaker, what is the final concentration?
0.01
The molecular weight of NaCl is 58.44 grams/mole. How many grams of NaCl are found in a beaker with 100.0 mL of a 0.0050 M solution? Round answer to 2 significant figures.
0.029
A 4,000 mL solution of AgNO3 contains 17.00 g of solute in water. Calculate the molar concentration of the solution. 0.03 M 0.4 M 908 M 700 M
0.03 M
The compound PCl5 decomposes into Cl2 and PCl3. The equilibrium of PCl5(g) Cl2(g) + PCl3(g) has a Keq of 2.24 x 10-2 at 327°C. What is the equilibrium concentration of Cl2 in a 1.00-liter vessel containing 0.235 mole of PCl5 and 0.174 mole of PCl3? Remember to use the correct number of significant digits. Cl2 = Are the products or reactants favored?
0.0303 M reactants
Calculate the molarity of the solution. 6.02 x 1022 molecules of HCl (molecular weight = 36.5 g/mole) in 2.0 liters of water
0.050
A solution contains 180 g of glucose (C6H12O6) and 162 g of water. What is the mole fraction of glucose?
0.10
The molecular weight of NaCl is 58.44 grams/mole. If you had a 1.0 molar solution (1.0 M), you would have to put 58.44 g of salt in 1.0 liter of solution. How many moles of NaCl would you have in 100 mL of this solution?
0.10
A reaction is in equilibrium as shown: A + B C + D. Calculate the equilibrium constant if the final concentrations stabilize at: A = 9.60 M B = 10.0 M C = 4.00 M D = 4.00 M 0.167 0.408 2.45 5.99
0.167
Calculate the molarity of the solution to 3 digits. 100.0 g of C12H22O11 (molecular weight = 342.28 g/mole) in 1.15 liters of solvent
0.254
Be sure to use proper significant figures. The molecular weight of NaCl is 58.44 grams/mole. With a 0.50 M solution: How many grams of NaCl would there be in 10.0 mL of solution?
0.29
Be sure to use proper significant figures for all remaining problems. How many grams of NaCl are present in 350 mL of 0.020 M NaCl solution? (Remember that 1 mole NaCl = 58.44 g/mole.)
0.41
Suppose that instead of a 1 M solution, you decided to make up a 0.5 M solution. How many moles of NaCl would there be in one liter?
0.5
With a 0.5 M solution: How many moles of NaCl would there be in 1,000 mL?
0.5
A 3.0 L solution contains 73.5 g of H2SO4. Calculate the molar concentration of the solution. M Approximately how much water must be added to the 3.0 L solution to dilute it to 0.18 M?
0.75, 1.2
1 kilocalorie = ______ Calorie(s)
1
1 kilocalorie is equal to __________ calories.
1,000
What is the atomic mass of one mole of H? _________________ g/mole
1.008
In the important industrial process for producing ammonia (the Haber Process), the overall reaction is: N2(g) + 3H2(g) → 2NH3(g) + 100.4 kJ A yield of NH3 of approximately 98% can be obtained at 200°C and 1,000 atmospheres of pressure. How many grams of N2 must react to form 1.7 grams of ammonia, NH3? 0.0058 g .052 g 1.4 g 2.8 g
1.4 g
A 7.83 g sample of NaCl is dissolved in 90.00 mL of ethyl alcohol (C2H3OH) solution. Calculate the molar concentration of the solution. 0.00149 M 1.49 M 5.08 M 12.1 M
1.49 M
H2(g) + CO2(g) + 10 kcal H2O(g) + CO(g) In another experiment involving the above reaction at 1,000°C, the equilibrium concentrations were found to be: H2(g) = 2.0 moles per liter H2O(g) = 4.0 moles per liter CO2(g) = 5.0 moles per liter CO(g) = 4.0 moles per liter What is the equilibrium constant, Keq, for this reaction? 0.40 1.6 0.63 2.5 0.80
1.6
If 1.2 kilograms of rust form on a bridge in five days, what should be the rate of reaction in grams per hour? (Recall that a bar over the number means that zero is significant.) 100 g/hr 0.05 g/hr 0.010 g/hr 10 g/hr
10 g/hr
The equilibrium system N2O4(g) 2NO2(g) was established in a 1.00-liter vessel. Upon analysis, the following information was found: [NO2] = 0.500 M; [N2O4] = 0.0250 M. What is the value of Keq?
10.0
What is the atomic mass of one mole of O? ___________ g/mole
16.00
436 K = ______°C
163
What is the molecular weight of one mole of H2O? _____________ g/mole
18.02
Balance this chemical equation. Choose "blank" for the box if no other coefficient is needed. Writing the symbol implies "1." _________H2O2 → __________H2O + ___________O2
2 2 blank
Balance this chemical equation. Choose "blank" for the box if no other coefficient is needed. Writing the symbol implies "1." __________ HCl + __________Zn → _______________ZnCl2 + ___________H2
2 blank blank blank
Calculate the molarity of the solution. 29 g of NaCl in 0.25 liters of water (The molecular weight of NaCl is 58.44 g/mole.)
2.0 M
The two balanced equations (1) and (2) are for reactions in which gaseous carbon dioxide is produced from the combustion of (1) solid carbon and (2) gaseous carbon monoxide. 1. C(s) + O2(g) CO2(g) + 94.0 kcal 2. CO(g) + ½ O2(g) CO2(g) + 67.6 kcal When 112 grams of carbon monoxide are consumed according to equation 2, which of the following occurs? (atomic weights: C = 12.0 g/mol, O = 16.0 g/mol) 1.0 mole of carbon dioxide is produced. 67.6 kcal of heat are generated. 2.00 moles of oxygen are consumed. 0.25 mole of carbon dioxide is produced. 0.50 mole of oxygen is consumed.
2.00 moles of oxygen are consumed
Determine the value for the following reaction. 2HI(g) + 2.4 kcal → H2(g) + l2(g) ΔH = _____ 2.4 kcal -2.4 kcal 0.0024 kcal -0.0024 kcal
2.4 kcal
Calculate the molarity of the solution. 4.32 x 102 moles of CH3COOH in 20.0 liters of water
21.6
What is the atomic mass of one mole of Na? _______________ g/mole
22.99
Be sure to use proper significant figures. The molecular weight of NaCl is 58.44 grams/mole. To prepare a 0.50 M solution: You would need to have ____________ grams of NaCl in 1,000 mL of water.
29
N2 + 3H2 2NH3 How many molecules of H2 are represented in the reaction? How many nitrogen atoms are represented in the reactants? How many moles of NH3 are formed?
3 2 2
Balance this chemical equation. Choose "blank" for the box if no other coefficient is needed. Writing the symbol implies "1." _______________NH4OH + ___________AlCl3 → ______________Al(OH)3 + _______________NH4Cl
3 Blank Blank 3
The combustion of 14 grams of CO according to the reaction CO(g) + ½O2(g) CO2(g) + 67.6 kcal gives off how much heat? 6,716 kcal 1,514 kcal 34 kcal 135 kcal none of the above
34 kcal
Balance this chemical equation. Choose "blank" for the box if no other coefficient is needed. Writing the symbol implies "1." ____________Al + ______________O2 → _______________Al2O3
4 3 2
3Fe + 4H2O Fe3O4 + 4H2 How many molecules of H2 are produced? How many oxygen atoms are found in the products? How many moles of Fe3O4 are formed? What is the ratio of the number of moles of Fe atoms to the moles of H2O molecules? How many hydrogen atoms are found in the reactants?
4 4 1 3/4 8
Which of the following statements is not correct? 0.20 mole of O2 = 6.4 g 0.75 mole of H2CO3 = 47 g 3.42 moles CO = 95.8 g 4.1 moles Li2O = 94 g
4.1 moles Li2O = 94 g
1 calorie = _______ Joules
4.184
Consider the following energy diagram. How much is the activation energy? 2.4 kcal/mole 14.4 kcal/mole 43.8 kcal/mole
43.8 kcal/mole
We can also use the equation for enthalpy change for physical phase changes. Consider the phase change H2O(l) → H2O(g). Calculate ΔHrxn. Use ΔHf values from the table above. ΔHrxn = _____ -527.6 kJ 44.0 kJ 527.6 -44.0
44.0 kJ
How many g of water are required to be mixed with 11.75 g of HgCl in order to make a 0.01 m solution? (Refer to the periodic table for atomic weights.) 40 g 5,000 g 2 x 106 g 2 x 108 g
5,000 g
The molecular weight of NaCl is 58.44 grams/mole. If you had a 1.0 molar solution (1.0 M), you would have to put 58.44 g of salt in 1.0 liter of solution. 100 mL of this solution would have ___________ grams of NaCl.
5.8
What would be the final volume of the new solution if the 0.2 M solution on the left were diluted to 0.04 M?
50 mL
What is the molecular weight of one mole of H2CO3? _______________ g/mole
62.03
The combustion of 1 mole of CO according to the reaction CO(g) + ½O2(g) CO2(g) + 67.6 kcal gives off how much heat? 67.6 kcal 1,514 kcal 33.3 kcal 135.2 kcal none of the above
67.6 kcal
How many grams of hydrogen peroxide (H2O2) must be added to 1,500 mL of water to produce a concentration of 1.33 m (molal solution)? (Recall that the density of water is 1.0 gram/mL.) 0.059 g 30.0 g 68 g 68,000 g
68 g.
During the reaction P4 + 5O 2 P4 O10, 1.5 moles of product was made in 30 seconds. What is the rate of reaction? 0.011 g/min 210 g/min 380 g/min 850 g/min
850 g/min
During the reaction P4 + 5O2 → P4O10, 1.5 moles of product were made in seconds. What is the rate of reaction? 0.011 g/min 210 g/min 380 g/min 850 g/min
850 g/min
For the reactions system 2H2(g) + S2(g) 2H2S(g), a 1.00-liter vessel is found to contain 0.50 mole of H2, 0.020 mole of S2, and 68.5 moles of H2S. Calculate the numerical value of the Keq of this system. K = _____ 6.9 x 10^3 9.4 x 10^5 1.1 x 10^6 1.4 x 10^4
9.4 x 10^5
During the reaction P4 + 5O2 → P4O10, 0.800 mole of product was made in 15.0 seconds. What is the rate of reaction? 56.8 g/min 227 g/min 908 g/min 13,600 g/min
908 g/min
The curves represent two possible reaction paths for the decomposition of ammonia, NH3. One can correctly conclude from the graph that the heat of the reaction corresponds to the interval labeled: A B C D E
A
What happens to the energy released by an exothermic reaction? (Select all that apply.) A. It is released to the surroundings. B. It raises the temperature of the products. C. It raises the temperature of the reactants. D. It increases the bond energy of the reactants.
A, B.
When the products of a reaction are hotter than the reactants: (Select all that apply.) A. the reaction is exothermic B. the reaction is endothermic C. the reactants lost internal energy D. the change in enthalpy is positive
A, C.
As this reaction takes place at higher temperatures, it is observed that the equilibrium shifts to the product side. The reaction may be written as follows: 2AB2 A2 + 4B + heat 2AB2 + heat A2 + 4B A2 + 4B 2AB + heat 2A + B4 4A2B + heat
A2 + 4B --> 2AB + heat
Catalysts can save money by essentially lowering the: (Select all that apply.) activation energy cost of reactants rate of reaction temperature required starting enthalpy (E1)
Activation energy Temperature required
Which of the following changes would decrease the rate of reaction? addition of a catalyst increasing the concentration of reactants decreasing the concentration of products additional heat to an exothermic reaction
Additional heat to an exothermic reaction
Which statement is correct regarding the reaction? After reaching equilibrium, the rate of formation of products is less than the rate of formation of reactants. After reaching equilibrium, the rate of forming products and reactants is the same. Equilibrium is obtained prior to Te.
After reaching equilibrium, the rate of forming products and reactants is the same.
The following are properties of compounds _____. vapor pressure density boiling point all of the above
All of the above
A mole of the element U (uranium) and a mole of CO2 have: the same molecular weight the same atomic mass an equal number of particles an equal number of atoms
An equal number of particles
Which statement about reversible reactions is correct? At equilibrium, the forward and reverse reactions stop at the appropriate concentrations. At equilibrium, the forward and reverse reactions continue indefinitely. At equilibrium, the rate of reaction of products divided by the rate of reaction of reactants equals the equilibrium constant, K.
At equilibrium, the forward and reverse reactions continue indefinitely.
The activated complex is located at point:
B
The collision between reactants is most likely to produce a reaction at point:
B
The curves represent two possible reaction paths for the decomposition of ammonia, NH3.One can correctly conclude from the graph that the smallest activation energy shown for the decomposition of NH3 corresponds to the interval labeled: A B C D E
B
Which reaction is endothermic? A. H2(g) + ½ O2(g) H2O(g), H = -57.82 kcal B. ½ N2(g) + O2(g) + 8.1 kcal NO2(g) C. ½ N2(g) + 3/2H2(g) NH3(g) + 11.0 kcal D. C(diamond) + O2(g) CO2, H = -94.50 kcal
B
Study the following two reactions. (Select all that apply.) C(graphite) + O2(g) CO2(g) + 94.05 kcal C(diamond) + O2(g) CO2(g) + 94.50 kcal What could you infer from the information given above? A. The enthalpy of CO2 is greater than the reactants. B. E2 - E1 is negative. C. Graphite and diamond have equal enthalpy. D. Both reactions are exothermic.
B ,D.
Which reactions are endothermic? (Select all that apply.) A. H2(g) + ½O2(g) H2O(aq), H = -57.83 kcal/mole B. ½ N2(g) + ½O2(g) NO(g), H = +21.6 kcal/mole C. ½N2(g) + O2(g) + 8.1 kcal NO2(g) D. ½N2(g) + 3/2 H2(g) NH3(g) + 11.0 kcal/mole E. NH3(g) ½N2(g) + 3/2 H2(g), H = +11.0 kcal/mole
B, C, E.
Which of the following equations represents an exothermic reaction? (Select all that apply.) A. NH3(g) + 12.0 kcal ½N2(g) + 3/2 H2(g) B. C(graphite) C(diamond), H = - 0.45 kcal C. C + 2S CS2, H = 27,550 cal D. CH4 + 2O2 CO2 + 2H2O + 212,800 cal E. 2H2O 2H2 + O2, H = +58 kcal
B, D, E.
When the products of a reaction are cooler than the reactants: (Select all that apply.) A. the reaction is exothermic B. the reaction is endothermic C. the reactants lost energy D. the change in enthalpy is positive
B, D.
When the products of a reaction have more energy than the reactants: A. the reaction is exothermic B. the reaction is endothermic C. the reactants gave up energy D. the H is positive
B, D.
Where does the energy needed for an endothermic reaction come from? (Select all that apply.) A. the reactants B. the products C. the product/reactant solution D. the environment when no solution is involved E. the change in enthalpy
C, D.
Which of the following reactions represents an exothermic reaction? NH3(g) + 12.0 kcal ½N2(g) + 3/2 H2(g) CH4 + 2O2 CO2 + 2H2O + 212,800 cal C + 2S CS2, H = 27,550 cal C(graphite) C(diamond), H = 0.45 kcal 2H2O 2H2 + O2, H = +58 kcal
CH4 + 2O2 CO2 + 2H2O + 212,800 cal
Which of the following is commonly used on food packages to measure the energy content? Joule calorie Calorie kilocalorie
Calorie
When a chemical reaction occurs, the physical and chemical properties of the reactants are the same as the properties of the products.
False
You may normally expect a slow reaction if a low activation energy is required.
False
The curves represent two possible reaction paths for the decomposition of ammonia, NH3.One can correctly conclude from the graph that the largest activation energy shown for the decomposition of NH3 corresponds to the interval labeled: A B C D E
E
Select all that apply. Which statements concerning this diagram are correct? Z = A.E. E1 > E2 E2 > E1 Hrxn is positive. Hrxn is negative.
E1 > E2 E2 > E1
2KClO3 2KCl + 3O2 In this equation, the number of atoms in the product is greater than the number of atoms in the reactant.
False
A +H means that energy is released from a reaction.
False
Activation energy is only required to start an exothermic reaction.
False
An equilibrium constant is not changed by a change in pressure.
False
The brackets used to express concentration, [ ], when making equilibrium constant calculations indicate grams per liter.
False
The general name for a substance added to a reaction that affects the rate but is not consumed in the reaction is called a complex.
False
The physical properties of a solution are not affected by the concentration of the components.
False
Consider the following reactions. (Note: (s) = solid , (1) = liquid, and (g) = gas) Mg(s) + ½ O2(g) MgO(s) + 146 kcal/mole H2(g) + ½ O2(g) H2O(g), H = -57.82 kcal/mole The temperature of the surroundings will:
Increase
Consider the equation 2NO2(g) N2O4(g). Using ONLY the information given by the equation, which of the following changes would increase the molar concentration at equilibrium of the product N2O4(g)? increase in pressure increase in temperature decrease in the concentration of NO2(g) decrease in temperature decrease in pressure
Increase in pressure
A company desires to produce nickel by refining nickel oxide and sulfide ores. The first step of the process will produce a nickel carbonyl gas, Ni(CO)4, by heating the ore. The second step is as follows: Ni(CO)4(g) Ni(s) + 4CO(g) How would you accelerate the production of Ni? Reduce the concentration of NiCO4. Increase the concentration of NiCO4. Withdraw CO from the products as it is forming. Add CO to the reaction.
Increase the concentration of NiCO4. Withdraw CO from the products as it is forming.
The rate of chemical reactions generally ______________ as the temperature is raised.
Increased
Consider the equation 2H2(g) + O2(g) 2H2O(g). H is negative. Which statement is true? The reaction is endothermic from left to right. Increased pressure would increase the rate of forming water vapor. Increased temperature would increase the rate of forming water vapor. The reactants are favored over the products.
Increased pressure would increase the rate of forming water vapor.
What happens to the energy release of an exothermic reaction? It is released to the surroundings. It raises the temperature of the reactants. It increases the bond energy of the reactants.
It is released to the surroundings.
Which of the following reactions is not a chemical reaction? melting an ice cube tarnishing of a silver spoon digestion of food the browning of a freshly sliced apple
Melting an ice cube
If the change of enthalpy of this reaction when proceeding from left to right is +14 kcal, which chemical equation is correct? N2O4 2 NO2 + 14 kcal N2O4 + 14 kcal 2 NO2
N2O4 + 14 kcal ---> 2 NO2
What happens to the concentration of both components in the system as volume decreases? increase of both NO2 less; N2O4 greater NO2 less; N2O4 less
NO2 less; N2O4 greater
A company desires to produce nickel from refining nickel oxide and sulfide ores. The first step of the process will produce a nickel carbonyl gas, Ni(CO)4, by heating the ore. The second step is as follows: Ni(CO)4(g) Ni(s) + 4CO(g) What effect on the process would be caused by increasing pressure? Ni would be produced at a higher rate. Ni would be produced at a lower rate. There would be no effect on this particular reaction.
Ni would be produced at a lower rate
Calorimetric studies show that the following reaction is exothermic: 2NO2(g) N2O4(g) + 14.1 kcal. Based on this information, which one—if any—of the following additional changes would increase the molar concentration at equilibrium of N2O4(g)? decrease in pressure increase in temperature decrease in concentration of NO2(g) stirring the reaction mixture none of the above
None of the above
The rate of a reaction is measured by how fast a ___________ is used up or how fast a __________ is formed.
Reactant Product
Match the atoms which might substitute for one another. Match the items in the left column to the items in the right column.
Si -C, K-Na, Nb-V, Cu-Ag, P-As, Mg-Ca
[A]a[B]b [C]c [D]d When the Keq value is large, the number representing [A]a[B]b must be ____________ than the number representing [C]c [D]d. This relationship means that the___________ must be favored and that the mixture at equilibrium is largely_____________.
Smaller Products Products
Chemical reactions can be detected by precipitation of a(n) ___________ from a solution.
Solid
The action of a catalyst can be explained in the following manner: The catalyst lowers the temperature of the reactants. The catalyst takes no part in the reaction but serves as a buffer between reactants and products. The catalyst prevents the reverse reaction. The catalyst makes it possible for the reaction to take place by another path that makes possible reaction at a lower energy.
The catalyst makes it possible for the reaction to take place by another path that makes possible reaction at a lower energy.
In a closed system containing three different gases as shown, X2 + Y2 2XY. Choose the two things that MUST happen as the volume of the system is decreased at constant temperature. The relative concentrations of each gas must change. The concentration of each gas will increase. The relative concentrations of each gas must remain constant. The concentration of each gas will not change.
The concentration of each gas will increase. The relative concentrations of each gas must remain constant.
What may be expected when K < 1.0? Choose the three correct statements. The concentration of one or more of the reactants is small. The concentration of one or more of the products is small. The reaction will not proceed very far to the right. The reaction will generally form more reactants that products.
The concentration of one or more of the products is small. The reaction will not proceed very far to the right. The reaction will generally form more reactants that products.
What may be expected when K < 1.0? Choose the three correct statements. The concentration of one or more of the reactants will be small. The concentration of one or more of the products will be small. The reaction will not proceed very far to the right. The reaction will generally form more reactants than products.
The concentration of one or more of the products will be small. The reaction will not proceed very far to the right. The reaction will generally form more reactants than products
What may be expected when K > 1.0? Choose the two correct statements. The concentration of one or more of the reactants is small. The concentration of one or more of the products is small. The reaction will not proceed very far to the right. The reaction will proceed to the right and favor the formation of products.
The concentration of one or more of the reactants is small. The reaction will proceed to the right and favor the formation of products.
Where does the energy needed for an endothermic reaction come from? the reactants the products the environment the change in enthalpy
The environment
Now dilute 10.0 mL of the 0.50 M NaCl by adding distilled water until 100 mL of solution are produced. Does the 100 mL of diluted NaCl have more, less, or the same quantity of NaCl as the original 10.0 mL of 0.50 M NaCl? more less the same
The same
What happens to the total number of molecules in the system as the pressure is reduced? N2O4(g) 2NO2(g) They must stay the same. They will increase. They will decrease. The total will fluctuate (increase and decrease).
They will increase
0.25 mole of O2 will contain the same number of molecules as 0.25 mole of NH3.
True
2KClO3 2KCl + 3O2 In the reaction represented by this equation, two moles of KClO3 decompose to form 5 moles of product.
True
2KClO3 2KCl + 3O2 In this equation, the number of molecules of product is greater than the number of molecules of reactant.
True
8Fe + S8 8FeS In the reaction represented by this equation, nine moles of reactants form 8 moles of product.
True
A liquid solution can be made from a solid, liquid, or gas solute.
True
An equilibrium is dynamic.
True
Color change is a good way to detect a chemical reaction.
True
Equilibrium systems exist throughout nature.
True
Solutions are a mixture of 2 or more compounds.
True
The energy level necessary to enable a reaction to occur is called the activation.
True
The reaction P4 + 5O2 --> P4O10 + 712 kcal is exothermic.
True
True or false? Chemical reactions can be detected by the formation of a gas.
True
What is happening when the reactants BEGIN to react? There are two correct statements. [A] + [B] decrease slowly. [A] + [B] decrease rapidly. [A] + [B] remain constant. [CD] decreases slowly. [CD] increases slowly. [CD] increases rapidly.
[A] + [B] decrease rapidly., [CD] increases rapidly.
For the reactions system 2H2(g) + S2(g) 2H2S(g), a 1.00-liter vessel is found to contain 0.5 mole of H2 , 0.02 mole of S2, and 68.5 moles of H2S. What is the equilibrium constant expression? Fill in the blanks with chemical formulas, not numbers. (Enter subscripts after the letters: for example, H2O = Hs2O. Also, don't forget to use the proper chemical shorthand for chemical symbols. For instance, chlorine = Cl but not cl or cL.)
[Hs2S]/ [Hs2][Ss2]
The equilibrium of 2H 2 O(g) 2H 2 (g) + O 2 (g) at 2,000 K has a Keq value of 5.31 x 10-10. What is the Keq expression for this system? (Enter subscripts after the letters: for example, H2O = Hs2O. Also, don't forget to use proper chemical shorthand for chemical symbols. For instance, chlorine = Cl but not cl or cL.)
[Hs2][Os2]/[Hs20]
Which is the correct expression for Keq when the chemical reaction is as follows: N2 + 3H2 2NH3
[NH3]^2/[N2][H2]^3
If this reaction is exothermic, what may be expected as the temperature is reduced? [Products] will decrease. [Products] will increase. [Reactants] will increase. Reduction in temperature has no effect.
[Products] will increase.
X + Y XY + heat What happens as the temperature is increased? [X] remains constant. [X] increases. [X] decreases.
[X] increases.
What is happening after Time (Te)? There are three correct statements. [A] + [B] = [CD] [reactants] > [products] [reactants] < [products] [A] + [B] remain constant. [Products] remain constant.
[reactants] > [products], [A] + [B] remain constant. [Products] remain constant.
The curves represent two possible reaction paths for the decomposition of ammonia, NH3. One can correctly conclude from the graph that the best explanation for the difference between (I) and (II) is that: the concentration of NH3 was increased the temperature was increased the N2 was removed as soon as it was formed a catalyst was added
a catalyst was added
Reaction rates are affected by concentration, collision geometry, and the presence of a catalyst. Which of the following statements is FALSE concerning these factors? Increasing the concentration of reacting particles increases the chance for collisions. A catalyst lowers the activation energy requirement. A reaction occurs each time particles of the reactants collide. The slowest reaction involved in a reaction mechanism determines the rate of overall reaction.
a reaction occurs each time particles of the reactants collide
Raising the temperature of a reacting system increases the rate of the reaction, but does NOT increase the: activation energy number of collisions fraction of the reacting particles which possess energies greater than the activation energy vibrational motions within the molecules average velocity of the reacting particles
activation energy
The appropriate geometric "fixing" of two atoms, which is necessary to start chemical rearrangement, is called the:
activation energy
The minimum energy required to start a reaction is: enthalpy (E1) enthalpy (E2) activation energy (A.E.) heat of reaction
activation energy (A.E.)
The minimum energy required to start a reaction is: enthalpy (E1) enthalpy (E2) activation energy (A.E.) the heat of the reaction
activation energy (A.E.)
Catalysts can save money by essentially lowering the: (Select all that apply.) activation energy cost of reactants rate of reaction temperature required starting enthalpy (E1)
activation energy, temperature required.
catalyst
affects the activation energy level
The purging of impurities from a compound by crystallization occurs: when the compound is put under great pressure when the compound is vaporized after the liquid melt cools back to a solid after condensation from the vapor phase
after the liquid melt cools back to a solid
Chemical changes ________ involve the breaking and making of chemical bonds.
always
In the reaction N2O4(g) 2NO2(g), what changes in color would you expect as pressure is increased at constant temperature? becomes lighter becomes darker will not change not enough information
becomes lighter
Balance the following reaction and use the equation to calculate the ΔHrxn. __________ C3H8(g) +____________ O2(g) → ___________ CO2(g) + __________ H2O(g) Round your answer to the nearest whole number. ΔHrxn=kJ/mole
blank, 5, 3, 4, -2044
Enthalpy is a form of: kinetic energy heat energy bonding energy within atoms temperature
bonding energy within atoms
What is the common device used for measuring heat transfer for chemical reactions? thermometer calorimeter molameter
calorimeter
_________________ : a substance that is added to a chemical reaction; changes the rate of the reaction, but is not consumed in the reaction and does not affect the equilibrium in any way
catalyst
a substance that changes the rate of the reaction, and is not consumed in the reaction
catalyst
Which of the following would not necessarily indicate a chemical reaction? change in temperature chemical precipitation of a solid production of a gas change in volume
change in volume
What type of reaction takes place when atoms or molecules rearrange to form new substances?
chemical
At STP conditions, 0.25 mole of CO2(g), H2(g), NH3(g) will: (Select all that apply.) contain the same number of molecules contain a different number of molecules occupy the same volume have the same molecular weight
contain the same number of molecules occupy the same volume
Which of the following does not indicate a chemical change? precipitate formation crushing a solid into a powder color change gas evolution
crushing a solid into a powder
The standard for entropy is defined by a perfectly ordered _____ at 0 K. molecule crystal metal compound
crystal
Consider the following reactions. ½ H2(g) + ½ I2(g) HI(g), H = +6.2 kcal/mole 21.0 kcal/mole + C(s) + 2S(s) CS2(l) The temperature of the surroundings will:
decrease
Consider two gases, A and B, that are in a container at room temperature. What effect will the following change have on the rate of the reaction between these gases? The temperature is decreased at a constant volume.
decrease
O2(g) O2(l) Predict whether the reaction above would have an increase or a decrease in entropy.
decrease
Ammonium hydroxide ionizes as follows: NH4OH(s) NH4 +(aq) + OH-(aq). If an excess of ammonium salt, such as NH4Cl (which ionizes to give NH4 +(aq) ions), is added to the equilibrium shown above, you could predict that the result will be to: decrease the concentration of NH4OH cause the temperature to greatly increase decrease the concentration of OH- increase the rate of the reaction to the right not disturb the equilibrium
decrease the concentration of OH-
Consider again the solution made by diluting 10.0 mL of the 0.50 M NaCl by adding distilled water until 100 mL of solution are produced. Has the concentration of the diluted salt solution increased, decreased, or remained constant? increased decreased remained constant
decreased
Based on the observations of the above test tubes, as the temperature is increased, the [N2O4]: decreases increases remains constant not enough information
decreases
Gibbs free energy is described by: deltaG = deltaS + TdeltaH deltaG = deltaH - TdeltaS deltaG = deltaS - TdeltaH deltaG = deltaH + TdeltaS
deltaG = deltaH - TdeltaS
The physical properties of a solution are ____________ the properties of its individual components.
different from
What is the relationship between concentration and rate of reaction? not related directly proportional inversely proportional partially related
directly proportional
+deltaH
endothermic
Consider the following energy diagram. What type of reaction does this diagram illustrate?
endothermic
Consider the following reactions. ½ H2(g) + ½ I2(g) HI(g), H = +6.2 kcal/mole 21.0 kcal/mole + C(s) + 2S(s) CS2(l) What type of reaction is represented by the previous two examples?
endothermic
Consider the phase change H2O(l) H2O(g). This equation describes the phase change from liquid water to steam. Think about the heat flow that is necessary for this change to take place. What do you predict about the process? It will be _________________
endothermic
If we read the reaction as X + Y → Z + Q it is ______________.
endothermic
The reaction diagram illustrates what type of reaction?
endothermic
a reaction that absorbs energy
endothermic
If the reaction producing nickel is as follows: Ni(CO)4(g) + heat Ni(s) + 4CO(g) - Heat The reaction from left to right is _________________ and, therefore, the addition of heat will ________________ the production of nickel.
endothermic accelerate
Select the correct match. +deltaH . E2 < E1 . energy is absorbed . E2 > E1 . -deltaH
endothermic exothermic endothermic endothermic exothermic
a reaction which absorbs heat from the surrounding space
endothermic reaction
The heat exchange in chemical reactions is due to a change in: kinetic energy enthalpy temperature physical properties
enthalpy
the amount of heat released or absorbed by a reaction
enthalpy
the heat added to or lost by a system at constant pressure
enthalpy
The amount of heat released or absorbed by a reaction
enthalpy of a reaction
A measure of the disorder of a system is called: enthalpy energy entropy synergy
entropy
Organic protein catalysts are called: enzymes carbohydrates lipids amino acids
enzymes
The mass of one mole of any substance is: equal to 6.02 x 1023 g equal to the sum of the atomic masses of every atom in the formula the same for all elements but not molecules the same for all elements and molecules
equal to the sum of the atomic masses of every atom in the formula
-deltaH
exothermic
A reaction that releases heat is ______________.
exothermic
the number of moles of solute per liter of solution
molarity
As this reaction takes place at higher temperatures, it is observed that the equilibrium shifts toward the products. The reaction is
exothermic
Consider the following reactions. (Note: (s) = solid , (1) = liquid, and (g) = gas) Mg(s) + ½ O2(g) MgO(s) + 146 kcal/mole H2(g) + ½ O2(g) H2O(g), H = -57.82 kcal/mole What type of reaction is represented by the previous two examples?
exothermic
In the important industrial process for producing ammonia (the Haber Process), the overall reaction is: N2(g) + 3H2(g) 2NH3(g) + 100.4 kJ A yield of NH3 of approximately 98% can be obtained at 200°C and 1,000 atmospheres of pressure. This reaction is:
exothermic
a reaction that releases energy
exothermic
a reaction that releases heat
exothermic
a reaction which gives up heat to the surrounding space
exothermic reaction
A temperature change in a reaction indicates a physical change.
false
Activation energy is only required to start an exothermic reaction.
false
All chemical reactions involving gas components will change their relative concentrations to adjust for pressure changes.
false
All gaseous mixtures are solutions.
false
All reactions involving a change in temperature are exothermic.
false
An endothermic reaction will start when the required H energy is received from the collision of particles in the reaction, the environment or solution.
false
Changing colors is not an indication of a chemical change.
false
Chemical reactions will occur if the products are less stable than the reactants.
false
Each particular chemical reaction can be expected to occur at the same rate.
false
Endothermic means to lose energy.
false
Energy can be measured directly with a calorimeter.
false
Equilibrium is the continual change from product to reactant and back.
false
Gas produced from a reaction is a phase change, not a chemical change.
false
Increased temperature generally decreases the rate of a reaction.
false
Solid solutions are only formed with metals.
false
The formation of a precipitate does not indicate a chemical reaction occurred.
false
The vapor pressure of water is not affected by the amount of salt added.
false
Two objects with the same temperature must have an equal quantity of heat.
false
When a chemical reaction occurs, the physical and chemical properties of the reactants are the same as the properties of the products.
false
If we reverse the reaction to read Z + Q → X + Y, the +ΔH would be a -ΔH. Does this indicate that heat is given off or absorbed in the reverse reaction?
given off
___________ is the measure of a quantity of energy.
heat
The change in enthalpy (heat content) that occurs in the process of converting reactants to products in a chemical reaction
heat of reaction
A mixture that does not have a uniform composition and the individual components remain distinct.
heterogeneous
A mixture which may be in more than one state is
heterogeneous
A mixture that does have a uniform composition throughout and is always in the same state.
homogeneous
Consider two gases, A and B, that are in a container at room temperature. What effect will the following change have on the rate of the reaction between these gases? The number of molecules of gas A is doubled.
increase
Consider two gases, A and B, that are in a container at room temperature. What effect will the following change have on the rate of the reaction between these gases? The pressure is doubled.
increase
H2O(g) H2 + O2(g) Predict whether the reaction above would have an increase or a decrease in entropy.
increase
Which of the following changes would increase the molar concentration of the products in any chemical reaction at equilibrium? decrease in pressure increase in temperature increase in the molar concentration of the reactants decrease in temperature addition of a catalyst
increase in the molar concentration of the reactants
The rate of chemical reactions ___________ as the temperature is raised.
increased
The Second Law of Thermodynamics states that the total amount of entropy in the universe is ____________.
increasing
A substance that will not dissolve in a solvent.
insoluble
Substance A will not dissolve in water. What can be said about substance A? It is nonpolar It is polar It is soluble It is unsaturated
it is nonpolar
In an exothermic reaction, the bonding energy of the product is: less than the reactants same as the reactants greater than the reactants dependent on the presence of a catalyst
less than the reactants
The chemical breakdown of enormous quantities of organic material buried in the sedimentary rocks has produced ________ gas.
methane
An element or compound which occurs naturally in the earth is a(n)
mineral
the number of moles of solute per 1000g of solvent
molaity
activation complex
molecular formation at the time of reaction
When a chemical reaction takes place, the number of atoms of each element in the reactants ______________ the number of atoms of each element in the products.
must be equal to
When a chemical reaction takes place, the number of atoms of each element in the reactants _______________ the number of atoms of each element in the products.
must be equal to
A reaction is spontaneous if ΔG is _____________.
negative
Reactions that are exothermic have Hf values that are __________.
negative
Concerning the 10.0 mL of 0.50 M NaCl diluted to100 mL of solution: When a solution is diluted, does the dilution change the number of grams dissolved?
no
Concerning the 10.0 mL of 0.50 M NaCl to 100 mL of solution: When a solution is diluted, does it change the number of moles dissolved?
no
Is it likely that an atom of Te would substitute for an atom of O in a solid compound? yes no impossible to determine
no
Is the following reaction spontaneous at 298 K? Answer by calculating G. H2O(g) + C(s) CO(g) + H2(g) H = 131.3 kJ/mole S = 134 J/mole.K
no
A molecule with no internal charge variation due to bonding.
nonpolar
a molecule with an uneven distribution of charge due to unequal sharing of electrons during bonding
polar
The heat content of a system is its _____. potential to store heat potential to release heat potential to exchange heat potential to overcome enthalpy
potential to release heat
When a solid compound is formed from chemicals that are in a solution, it is called a _____________________.
precipitate
the solid formed as a result of a chemical reaction involving solutions
precipitate
the solid formed as a result of chemicals reacting together from a solution
precipitate
Consider the following energy diagram. Do the reactants or products have more enthalpy?
products
ΔHrxn = (sum of ΔHf ___________ - sum of ΔHf _____________ )
products, reactants.
H2 + I2 2HI + 3 kcal The formation of ______________ was favored by the addition of heat.
reactants
Which is more stable, the reactants or products?
reactants
Reactions which do not continue to completion are called __________________ reactions.
reversible
A solution which has dissolved as much solute as it can at a particular temperature.
saturated
Two teaspoons of salt are added to a glass of water which is then stirred until no more salt grains can be seen. Two more teaspoons are added and stirring is continued, but the salt grains are still evident in the glass and settle to the bottom. After the addition of the last two teaspoons of salt the solution is ___________________________. nonpolar polar saturated unsaturated
saturated
In order for one type of atom to substitute for another in a solid solution, the substituting atom must be: (Select all that apply.) the same element identical in size similar in size from the same period from the same group
similar in size from the same group
The component which dissolves in a solution is called the:
solute
the substance dissolved in a solution
solute
A homogeneous mixture
solution
a uniform mixture of molecules or ions of one substance in another
solution
that component of a solution which dissolves the solute
solvent
the substance that does the dissolving in a solution
solvent
the amount of heat required to raise the temperature of one gram of a given substance by one degree Celsius
specific heat
Select all that apply. Chemical reactions can be detected by changes in: temperature color overall mass of the products compared to the mass of the reactants density of the products compared to the reactants
temperature color density of the products compared to the reactants
In the reaction aA + bB ---> cC + dD, the lowercase letters represent: the concentration in moles per liter the number of moles of each component in the reaction vessel the coefficients of the balanced reaction
the coefficients of the balanced reaction
In the reaction aA + bB cC + dD, the lowercase letters represent: the concentration in moles per liter the number of moles of each component in the reaction vessel the coefficients of the balanced reaction
the coefficients of the balanced reaction
When the concentration of a system is changed: the equilibrium constant changes either the numerator or the denominator of the mass action expression will change the mass action expression changes exponents the concentrations change to maintain the original value of K
the concentrations change to maintain the original value of K
The solvent is usually referred to as the component of a solution which is present as: (Select all that apply.) one liter the larger quantity the liquid which dissolves a solid the smaller quantity
the larger quantity the liquid which dissolves a solid
From the diagram, when the temperature of reactants are raised from 20°C to 30°C: the average kinetic energy doubles the number of molecules doubles the total number of collisions doubles the number of molecules having Er or greater doubles
the number of molecules having Er or greater doubles
The two balanced equations (1) and (2) are for reactions in which gaseous carbon dioxide is produced from the combustion of (1) solid carbon and (2) gaseous carbon monoxide. 1. C(s) + O2(g) CO2(g) + 94.0 kcal 2. CO(g) + ½ O2(g) CO2(g) + 67.6 kcal On the basis of the information given in equation (1) and assuming no change in temperature or pressure, one can correctly conclude that the rate of reaction is rapid the total number of moles of products is the same as the total number of moles of reactants the reaction is exothermic the weights of the products are greater than those of the reactants there will be an increase in the volume of the reactants and products taken together as the reaction proceeds
the reaction is exothermic
The requirement that a reversible reaction be at equilibrium is that: the concentrations on the two sides of the arrow be equal the velocity for the forward reaction equals that of the reverse reaction there will be as many molecules of the substances on one side of the arrow as there are molecules of the substances on the other side the moles of products will equal the moles of reactants
the velocity for the forward reaction equals that of the reverse reaction
What is the significance of "Er" in the diagram? average molecular energy threshold energy for reaction maximum kinetic energy minimum kinetic energy
threshold energy for reaction
"Rate" is related to: volume time distance percentage
time
A compound with a large negative H may not require activation energy.
true
A general term for a chemical which accelerates a reaction without becoming chemically involved is called a catalyst.
true
A measure of the kinetic energy of particle motion within a substance is temperature.
true
A negative deltaH means an exothermic reaction.
true
Alloys are examples of solid solutions.
true
Crystallization is a good way to purify solids.
true
Increased concentration generally increases the reaction rate.
true
Salt acts as an antifreeze.
true
The activation energy of an endothermic reaction must be greater than the required H.
true
The formation of a precipitate is an indication of a chemical change.
true
The formation of a solid when two liquids are mixed indicates a reaction.
true
The orderly geometric arrangement of atoms is called a crystalline solid.
true
The rate of a reaction is measured by how fast a reactant is used up or how fast a product is formed.
true
When a solid compound is formed from chemicals that are in a solution, it is called a precipitate.
true
When the stabilized state of an equilibrium system is altered, further chemical reactions begin until a new equilibrium is reached.
true
You may normally expect a slow reaction rate if a large A.E. is required.
true
A solution which is still able to dissolve solute.
unsaturated
precipitation
way to detect reactions.
Concerning the 10.0 mL of 0.50 M NaCl to 100 mL of solution: Does dilution change the concentration?
yes
If a reaction has a ΔG of -136kJ at 110°C, will it be spontaneous at this temperature (110°C)?
yes
Which of the following reactions is endothermic? H2(g) + ½ O2(g) H2O(g), H = -57.82 kcal ½N2(g) + O2(g) + 8.1 kcal NO2(g) ½ N2(g) + 3/2 H2(g) NH3(g) + 11.0 kcal C(diamond) + O2(g) CO2, H = -94.50 kcal
½N2(g) + O2(g) + 8.1 kcal NO2(g)
