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Question
Which of the following combinations would be best to buffer an aqueous solution at a pH of 9.0?
A.H3PO4 and H2PO4-, Ka1 = 7.5 10-3
B.HNO2 and NO2-, Ka = 4.5 10-4
C.CH3CO2H and CH3COO-, Ka = 1.8 10-5
D.H2PO4- and HPO42-, Ka2 = 6.2 10-8
E.NH4+ and NH3, Ka = 5.7 10-10
Answer
This answer is hidden. It contains 2 characters.
Related questions
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Q:
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Q:
Assume that the following endothermic chemical reaction is at equilibrium.
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B.
C.
D.
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If the reaction quotient, Q, is equal to K in a gas phase reaction, then
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Q:
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Q:
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For the reaction A B, the rate law is
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B.
C.
D.
E.
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What is the overall order of the reaction below
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Q:
Which statement concerning relative rates of reaction is correct for the chemical equation given below?
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Q:
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Q:
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Q:
The rate constant at 366 K for a first-order reaction is 7.7 10-3 s-1 and the activation energy is 15.9 kJ/mol. What is the value of the frequency factor, A, in the Arrhenius equation? (R = 8.314 J/Kmol)A.0.0047 s-1B.0.70 s-1C.0.93 s-1D.1.1 s-1E.1.4 s-1
Q:
Calculate the activation energy, Ea, forN2O5(g) 2 NO2(g) + 1/2 O2(g)given k (at 45.0 C) = 5.79 10-4 s-1 and k (at 60.0 C) = 3.83 10-3 s-1. (R = 8.314 J/Kmol)A.0.256 kJ/molB.2.83 kJ/molC.31.1 kJ/molD.111 kJ/molE.389 kJ/mol
Q:
What is the half-life of a first-order reaction if it takes 4.4 10-2 seconds for the concentration to decrease from 0.50 M to 0.20 M?A.2.5 10-2 sB.3.3 10-2 sC.1.6 sD.21 sE.27 s
Q:
Hydrogen peroxide decomposes into water and oxygen in a first-order process.
H2O2(aq) H2O() + 1/2 O2(g)
At 20.0 C, the half-life for the reaction is 3.92 104 seconds. If the initial concentration of hydrogen peroxide is 0.52 M, what is the concentration after 7.00 days?
A.1.2 10-5 M
B.0.034 M
C.0.074 M
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E.0.52 M
Q:
A student analyzed a first-order reaction and obtained the graph below. Unfortunately, the student forgot to label the axes. What are the correct labels for the x and y axes? A.x axis = time, y axis = ln[A]
B.x axis = ln[time], y axis = [A]
C.x axis = ln[time], y axis = [A]
D.x axis = time, y axis = 1/[A]
E.x axis = 1/time, y axis = 1/[A]