1) Why are alkynes considered acidic and then also considered good nucleophiles?…Aren't bases good nucleophiles?…” (Note: Explain the acidic nature of alkynes and how they can be converted to good nucleophiles. )

2) Explain the concept of Solvolysis in a way it is easy to understand

What is the energy per mole of photons of light with a wavelength of 812.4 nm? a.) 2.45 x 10^-19 KJ/mol b.) 1.47 x 10^2 KJ/mol c.)4.89 x 10^14 KJ/mol d.) 2.22 x 10^35 KJ/mol e.) 3.69 x10^14 KJ/mol (please show work)

Which has the smallest Zeff for its valence electrons?
A) F
B) Cl
C) Br
D) I
E) A-D all have the same Zeff

1)Using average bond enthalpies, predict which of the following reactions will be most exothermic:

a) C(g) + 2 F2(g)

b) CO(g) +3 F2(g) CF4(g) + OF2(g)

c) CO2(g) + 4 F2(g) CF4(g) + 2 OF2(g)

2) Ammonia is produced directly from nitrogen and hydrogen. The chemical reaction is N2(g) + 3 H2(g) 2 NH3(g)

N≡N

a) Use Table 8.4 p 326 in textbook (or you can find the table in the chapter 5 slides on the UR course), to estimate the enthalpy change using the bond enthalpy for the reaction. Is it exothermic or endothermic?

b) Calculate the standard enthalpy change for this reaction, using standard enthalpies of formation ΔHf°.

Please show step by step solution. Thanks!

Titrate 100.0mL of 0.0500M Fe2+ with 0.100M Ce4+. The equivalence point is when volume of Ce4+ added is 50.0mL. Find the voltage of the cell at the following points: a. 20.0mL b. 36.0mL c. 50.0mL d. 51.0mL e. 63.0mL

The automobile fuel called E85 consists of 85% ethanol and 15% gasoline. E85 can be used in so-called flex-fuel vehicles (FFVs), which can use gasoline, ethanol, or a mix as fuels. Assume that gasoline consists of a mixture of octanes (different isomers of C8H18), that the average heat of combustion of C8H18(l) is 5400 kJ/mol, and that gasoline has an average density of 0.70 g/mL. The density of ethanol is 0.79 g/mL.

Part C Assume that the density and heat of combustion of E85 can be obtained by using 85% of the values for ethanol and 15% of the values for gasoline. How much energy could be released by the combustion of 3.0 L of E85?

(A) The volume of water needed to dissolve 0.0510 grams of magnesium fluoride is ____  L.

Assume no volume change upon addition of the solid.

(B) A 16.3 mL sample of a 0.494 M aqueous nitrous acid solution is titrated with a 0.320 M aqueous potassium hydroxidesolution. What is the pH at the start of the titration, before any potassium hydroxide has been added?

pH = ?

1) Succinyl-CoA inhibits both citrate synthase and α-ketoglutarate dehydrogenase. How is succinyl-CoA able to inhibit both enzymes?

Here are four problems (5 pts each) involving the calculation of DG°' for metabolic reactions we have discussed, based on experimentally determined redox potentials. Calculate the DG°' for each reaction using the equation DG°' = -nFDE₀' and the values for E₀' given in Table 1. Show your work and circle your answer.

Table 1. Reduction potentials for reduction half reactions:

1/2 O₂ + 2H⁺ + 2e^- ® H₂O                                              E₀' = +0.82 V

fumarate + 2H⁺ + 2e^- ® succinate                                  E₀' = +0.03 V

oxaloacetate + 2H⁺ + 2e^- ® malate                                 E₀' = -0.17 V

pyruvate + 2H⁺ + 2e^- ® lactate                                       E₀' = -0.19 V

a-ketoglutarate + CO₂ + 2H⁺ + 2e^- ® isocitrate               E₀' = -0.38 V

FAD + 2H⁺ + 2e^- ® FADH₂                                             E₀' = -0.22 V

NAD⁺ + 2H⁺ + 2e^- ® NADH + H⁺                                    E₀' = -0.32 V

CoQ + 2H⁺ + 2e^- ® CoQH₂                                            E₀' = +0.06 V

Problem 3. malate + NAD⁺ ® oxaloacetate + NADH + H⁺

Problem 4. FADH₂ + CoQ ® FAD + CoQH₂

A buffered solution contains 0.25 M NH3 (Kb = 1.8 x 10-5 ) and 0.40 M NH4Cl.

a. Calculate the pH of this solution.

b. Calculate the pH of the solution that results when 0.20 mole of gaseous HCl is added to 1.0 L of the buffered solution from part a

Determine the Ka of an acid whose 0.364M solution has a pH of 1.80.

Assume for the moment that air consists of 80.00% nitrogen (N2) and 20.00% oxygen (O2) by volume. Use these figures and typical values for temperature and pressure (1.000atm and 25.00°C) to calculate the density of air in g/L.

A. Calculate the pH of a solution formed by combining 0.125 mL of 0.55 M HI with 0.400 mL of 0.14 M KOH at 25°C.
B. Calculate the pH of a solution formed by combining 0.125 mL of 0.55 M HI with 0.400 mL of 0.18 M KOH at 25°C.
C. A 50.00-mL sample of 0.0750 M HCN was titrated with 0.3995 M NaOH. What is the pH of the resulting solution after 5.00 mL of NaOH were added at 25°C? Ka for HCN is 6.2x10–10 at 25°C.
D. A 50.00-mL sample of 0.225 M HCO₂H was titrated with 0.1125 M NaOH. What is the pH at the equivalence point at 25°C?  Ka for HCO₂H is 1.8x10^–4 at 25°C.
E. A 25.00-mL sample of 0.225 M HNO₂ was titrated with 0.1111 M NaOH. What is the pH at the equivalence point at 25°C? Ka for HNO₂ is 7.2x10–4 at 25°C.
F. A solution of 0.600 g of diprotic acid in 100.0 mL of water was titrated with 0.300 M NaOH to the second equivalence point. The volume of the base used was 34.5 mL. What is the molar mass of acid in g/mol?
G. The solubility of Gd₂(SO₄)₃ is 4.0 g/100 mL. What is the Ksp?
H. What is the molarity of Ba²⁺ in a saturated solution of Ba₃(AsO₄)₂? (Ksp = 1.1 x 10^-13)
I. What is the concentration of Mg²⁺ when MgF₂ (Ksp = 6.4 x 10^-9) begins to precipitate from a solution that is 0.20 M F^-?
J. What is the pH of a saturated solution of Pb(OH)₂ (Ksp = 1.2 x 10^-5)?

please answer showing steps ( A to J )

Polystyrene has a statistical segment length of 0.67 nm in the melt and a density of 1.05 g/cm**3.

*find the molecular weight of repeated unit

* Find the characterstic ratio C∞for polystyrene using the known bond distances. Bond lenght of C-Cbond is 0.154nm

* Find the contour length of a PS chain of molecular weight M = 70,000 g/mol.

* Find the persistent length of PS, and give the physical meaning of persistent lenght