OC userin Chemistry·25 Nov 20172. In electrochemistry, what kind of reaction can be driven by electricity?
OC userin Chemistry·23 Nov 201796. Consider the reaction in which HCl adds across the double bond of ethene: | HCl + HỌC=CH2 – HẠC-CHÚC The following mechanism, with the accompanying energy dia- gram, has been suggested for this reaction: Step 1 HCl + H2C=CH2 —> H2C=CH2+ + Clº Step 2 H2C=CH2 + Cl - H3C-CH_CI +---E Energy A rxn - - -- - - C=C + HCI H-CC - Reaction progress- a. Based on the energy diagram, determine which step is rate limiting. b. What is the expected order of the reaction based on the pro- posed mechanism? c. Is the overall reaction exothermic or endothermic?
OC userin Chemistry·23 Nov 201781. Suppose that a catalyst lowers the activation barrier of a reac- tion from 125 kJ/mol to 55 kJ/mol. By what factor would you expect the reaction rate to increase at 25 °C? (Assume that the frequency factors for the catalyzed and uncatalyzed reactions are identical.)
OC userin Chemistry·25 Nov 2017110. Determine if HNO3 can dissolve each metal sample. If it can, write a balanced chemical reaction showing how the metal dissolves in HNO3 and determine the minimum volume of 6.0 M HNO3 required to completely dissolve the sample. a. 5.90 g Au b. 2.55 g Cu c. 4.83 g Sn
OC userin Chemistry·22 Nov 201732. Consider the reaction: NO2(g) — NO(g) + O2(8) The tabulated data were collected for the concentration of NO2 as a function of time: Time (S) [NO2] (M) 1.000 10 0.951 0.904 0.860 0.818 SOR 0.778 0.740 0.704 80 0.670 90 0.637 100 0.606 a. What is the average rate of the reaction between 10 and 20 s? Between 50 and 60 s? b. What is the rate of formation of O, between 50 and 60 s?
OC userin Chemistry·23 Nov 2017115. A buffer is created by combining 150.0 mL of 0.25 M HCHOZ with 75.0 mL of 0.20 M NaOH. Determine the pH of the buffer.
OC userin Chemistry·21 Nov 201777. A voltaic cell consists of a Zn/Zn2+ half-cell and a Ni/Ni2+ half-cell at 25°C. The initial concentrations of Ni2+ and Zn2+ are 1.50 M and 0.100 M, respectively. a. What is the initial cell potential? b. What is the cell potential when the concentration of Ni2+ has fallen to 0.500 M? c. What are the concentrations of Ni2+ and Zn2+ when the cell potential falls to 0.45 V?
OC userin Chemistry·21 Nov 2017118. A 250.0-ml buffer solution initially contains 0.025 mol of HCHO2 and 0.025 mol of NaCHO2. In order to adjust the buffer pH to 4.10, should you add NaOH or HCl to the buffer mixture? What mass of the correct reagent should you add?
OC userin Chemistry·23 Nov 2017Q4. Calculate the change in entropy that occurs in the system when 1.00 mol of methanol (CH3OH) vaporizes from a liquid to a gas at its boiling point (64.6°C). For methanol, AHvap = 35.21 kJ/mol. a) 104J/K b) -104J/K C) 545J/K d) -545 J/K
OC userin Chemistry·20 Nov 2017120. A 0.5224-g sample of an unknown monoprotic acid was titrated with 0.0998 M NaOH. The equivalence point of the titration occurred at 23.82 mL. Determine the molar mass of the unknown acid.
OC userin Chemistry·21 Nov 201799. Find the velocity of an electron emitted by a metal with a threshold frequency of 2.25 X 1014s when it is exposed to visible light of wavelength 5.00 x 10-?m.
OC userin Chemistry·21 Nov 2017Q10. The rate constant for a reaction at 25.0°C is 0.010s-1, and its activation energy is 35.8 kJ. Find the rate constant at 50.0°C a) 0.021 s-1 b) 0.010s-1 c) 0.0033s-1 d) 0.031 s-1
OC userin Chemistry·18 Nov 2017c. What are the posible values of mykezeschvalme og 60. What are the possible values of my for each value of I? a. O b. 1 c. 2 d. 3
OC userin Chemistry·16 Nov 201778. Consider this two-step mechanism for a reaction: NO2(g) + Cl2(8) CINO2(8) + C1(8) Slow NO2(g) + CI(g) , CINO2(8) Fast a. What is the overall reaction? b. Identify the intermediates in the mechanism. c. What is the predicted rate law?
OC userin Chemistry·16 Nov 201757. Which electron is, on average, closer to the nucleus: an electron in a 2s orbital or an electron in a 3s orbital?