We have a solution of protein that has a concentration of 0.25 mg/ml.

a.We need 20 g of the protein for an experiment. What volume of the protein solution do we need?

b.Suppose we want a solution containing 150 g of the protein at a concentration of 0.50 mg/ml. To do this we will first evaporate the liquid from enough of the protein solution to get 150 g. How much solution do we need to start with? How much H₂O do we add to get the desired concentration?

d.Suppose we want 1 ml of a 10 g/ml solution. How much H₂O and protein stock must we add to get this?

e.Suppose we want 100 l of a 0.1 g/l solution. How much H₂O and protein stock must we add to get this?

A solution of fructose, C₆H₁₂O₆, a sugar found in many fruits, is made by dissolving 38.0 g of fructose in 1.00 kg of water. What is the molal concentration of fructose the solution? What is the mole fraction of fructose in the solution? What is the mass percent of fructose in the solution? What is the molarity of the fructose solution if the density of the solution is 1.0078 g/mL?

Part A

How many milliliters of 0.135  M  HCl are needed to completely neutralize 46.0 mL of 0.101  M  Ba(OH)2 solution?

Part B

How many milliliters of 0.126  M  H2SO4 are needed to neutralize 0.180 g of NaOH?

Part C

If 55.6 mL of BaCl2 solution is needed to precipitate all the sulfate ion in a 758 mg sample of Na2SO4, what is the molarity of the solution?

Part D

If 42.1 mL of 0.204  M  HCl solution is needed to neutralize a solution of Ca(OH)2, how many grams of Ca(OH)2 must be in the solution?

Experiment: Synthesis of Benzoin:

2.6g of thiamine hydrochloride in a flask was dissolved in 8ml of water, 30 ml of ethanol was added and cooled on an ice bath. 5ml of 3M Sodium Hydroxide was added. 15ml of benzaldehyde was added and heated for 1hr.

Question 1:  how would the amount of  of reagents change if the amount of benzaldehyde was reduced to 1 ml. with calculations please?

Question 2: What is the theoretical weight of the product with calculations please?

Concept questions: 1) Acetic acid is a weak acid. Why is a 2M solution of acetic acid less hazardous than a 2M solution of hydrochloric acid? 2) What species must be present in a buffer? Write a chemical reaction that explains how the buffer reacts with acid and then write a chemical reaction that shows how the buffer reacts with base. Wxplain how a buffer works.

H2 + I2 yields 2HI

At the start of the reaction 1 mole of I2 and 1 mole of H2 are put into a 10 liter container. There is no HI present. At the reaction temperature Keq is 64

What is the equilibrium concentrations for H2, I2 and HI?

Would cyclohexanone have 2 or 3 unique hydrogen for H-NMR?

Why are cold solvents preferred during recrystallization and when is recrystallization selected vs other purification techniques?

In some materials the relationship between stress and strain during plastic deformation is given by σ = σ_y+ K(ε − ε_y) ⁿ  where K and n are constants. What is the energy absorbed by the specimen during plastic deformation in a tensile test if the material yields at a strain of ε_y and fails at a strain of ε_f?

How do potassium sorbate and benzoate kill yeasts and molds? Would they impart an off-flavor in food?

Suppose you have an organic sample X that is somewhat soluble in water, even though it is

somewhat more soluble in dichloromethane or ether solvents. But if you do a single

extraction, you get only 60% of your material to transfer from the water to the organic layer.

a) How many “washes” would it take to extract over 90% of your organic material from

the water layer?

b) In this case, would it be better to extract with dichloromethane or with ether?

Assume you changed the solvent to ethyl acetate which has a K_D for caffeine of 10. How much caffeine would you extract after three extractions? Show your work.

Discuss the microstructure of polymers based on the geometrical structure.

1-1Based on the Gibbs free energy of formation of substances listed in the table below, calculate EMF for the following cells:

(i) Zn | Zn²⁺ (1.0 M) || H⁺ (1.0 M) | O₂ (1 atm) | Pt

(ii) Zn | Zn²⁺ (1.0 M) || Cu²⁺ (1.0 M) | Cu

(iii) Pt | H₂(g) (1 atm) | H⁺ (1.0 M) || H⁺ (1.0 M) | O₂ (1 atm) | Pt

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Substances                               DG_f^o/ kJ mol^-1 (298 K)

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Zn²⁺(aq)                                  -147.0

ZnO(s)                                     -318.3

Mn²⁺(aq)                                 -228.3

MnO₄^-(aq)                               -447.3

MnO₂(s)                                  -465.2

Mn₂O₃(s)                                 -881.15

OH^-(aq)                                   -157.2

H₂O(l)                                     -237.1

Cu²⁺(aq)                                  +65.52

Cu⁺(aq)                                    +50.0

Fe³⁺(aq)                                   -4.6

Fe²⁺(aq)                                   -78.87

Cr³⁺(aq)                                   -197.05

CrO₄^2-(aq)                               -727.8

Cr₂O₇^2-(aq)                             -1301.2

Ce³⁺(aq)                                  -672.0

Ce⁴⁺(aq)                                  -533.06

Ag⁺(aq)                                   +77.12

AgCl(s)                                   -109.8

Cl^-(aq)                                     -131.3

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Calculate delta H for the reaction H(g) + Br(g) = HBr(g), given the following information:

H2(g) + Br2(g) = 2HBr(g) delta H = -72 kJ

H2(g) = 2H(g) delta H = +436 kJ

Br2(g)= 2Br(g) delta H = +224 kJ