A student makes a solution containing ammonium chloride and ammonium bromide salts dissolved in concentrated sulfuric acid. She adds a portion of tert-butyl alcohol and shakes the mixture vigorously. After allowing the layers to separate, she dried the alkyl halide layer that resulted and analyzed it by GCMS.

a. Predict the products and their approximate percentages.

b. Draw the complete mechanisms to explain the formation of the products.

c. Explain your percentage predictions

d. Would the change to an aprotic solvent such as DMSO have an effect on the product ratio? How?

1.In gravimetric analysis, it is possible to use the common-ion effect to favor the production of solid precipitate. In this problem you will test this approach to see how effective it is for the gravimetric determination of calcium. Suppose the reaction flask in the gravimetric analysis experiment contains 175 mL of solution before filtering through the Gooch crucible. A precipitate of calcium oxalate monohydrate is collected in the crucible and dried, where:

CaC2O4 * H2O <--> Ca2^+ + C2O4^2- + H2O    Ksp=1.3x10^-8

The measured dry mass of CaC₂O₄·H₂O precipitate is 0.4324 g. In this problem you will determine the mass of Ca²⁺ that remains in the filtrate and is therefore unaccounted for in the precipitate. Specifically, please do the following:

(a) Determine the moles of oxalate ion in the 175-mL reaction flask before precipitation. Use the experimental information in the lab manual. For the purposes of this problem, assume the oxalate ion is totally deprotonated.

(b) Determine the equilibrium molarity of dissolved Ca²⁺ after the precipitation has occurred. [Hint: assume the precipitation first goes to completion; i.e., all the calcium ion from the original sample is in the precipitate. Then set up an ICE table to determine the amount (in moles/L) of the calcium ion that goes back into solution via solubility equilibrium subsequent to the precipitation. Note carefully that that the oxalate (“common ion”) is in excess before the precipitation.]

(c) Determine the mass (in g) of dissolved Ca²⁺ that remains in solution following filtration.

(d) Determine the mass (in g) of calcium ion in the solid precipitate.

(e) From your answers to (c) and (d), determine what percentage of the original calcium mass is lost to the filtrate.

(f) Repeat parts (b) through (e) under conditions in which the oxalate is not in excess; in other words, set the initial oxalate concentration in your ICE table to zero.

1. Write the acid dissociation reaction for following solutions, and calculate the pH for each of them: a) 0.001 M HCl b) 0.005 M H2SO4 c) 0.005 M KOH

Design a separation scheme to separate cations, Al3+, Cu2+, Ni2+, Ag+.

In the Debye-Huckel equation describing the true activity of ions in solution, name and describe 6 terms contained therein that affect the activity, and explain how they do affect it.

(a) What are the disadvantages of using too little drying agent? (b) What are the disadvantages of using too much drying agent?

A Carnot cycle uses 1.00 mol of a monoatomic perfect gas as the working substance from an initial state of 10.0 atm and 600 K. It expands isothermally to a pressure of 1.00 atm (step 1), and then adiabatically to a temperature of 300 K, (step 2). This expansion is followed by an isothermal compression (step 3), and then an adiabatic compression (step 4) back to the initial state. Determine the values of q, w, ÄU, ÄH, ÄS, and ÄSsurr for each step in the cycle and the cycle as a whole. (Express your answer as a table of values). Calculate the efficiency of an energy that uses this cycle. Actually, do this calculation two different ways and see if they agree with each other.

Calculate the pH of a titration with 25 mL of 0.1 M NH3 with 0.1 MHCl at the following volume points: 0, 10, 24.9, 25, 25.1, 40,50 mL

Calculate pCa2+ for the titration of 25.00 mL of 0.0200 M EDTA with 12.0 mL of 0.01000 M CaSO4 at pH 10.00.

In a FRET experiment, the donor GFP (GFP absorbs at 487 nm, emits at 510 nm) is attached to protein A, and the acceptor YFP (YFP absorbs at 514 nm, emits at 535 nm) is attached to protein B. The value of ro is 10Å. a. If protein A does not bind to protein B, fluorescence will be observed at what wavelength b. At pH 6, the distance between the proteins is 25 Å. What is the efficiency? c. Increasing the pH from 6 to 12 causes the efficiency to increase to 0.9. Calculate the separation distance at pH 12.

In theory, what could be done experimentally to change the value of A (frequency factor in Arrhenius equation)? Explain the effect in molecular terms.

1.   A solution of 0.05M KMnO₄ was titrated with a solution of 0.268g Na₂C₂O₄ 100mL. What is the volume of KMnO₄ required to the end point?

2.   Calculate the % C₂O₄^2- in each of the following :-

a.   Na₂C₂O₄

b.   K₂[Cu (C₂O₄)₂].2H₂O

how does the flouride-ion selective electrode detect the flouride ion?