Calculate the molarity of the following solutions.

a) 0.950 mol of Na2S in 1.85 L of solution.

___M

b) 30.9 g of MgS in 833 mL of solution.

___M

the aldrich chemical company once manufactured a technical(low purity) grade of pinene that contained 85%(+)- alpha pinene and had a specific rotation of +43. is the 15% (by mass) impurity in this product more likely to be (-)-alpha-pinene, (-)-beta-pinene, or some optically inactive substance? justify your answer with calculations.

Consider the reaction:

2SO_2(g)+O_2(g)--->2SO_3(s)

(a) If 285.5 mL of SO₂ is allowed to react with 158.9mL of O₂ (both measured at STP), what is the limiting reactant and the theoretical yield of SO₃?

(b) If 2.805g of SO₃ is collected (measured at STP), what is the percent yield for the reaction?

A steel reaction vessel at 25 oC initially contained pure NO2 at a concentration of 2.0 x 10-4 mol/L. Some of the NO2 reacted to form N2O4 as described by the following equilibrum equation:

2NO2(g) <----------> N2O4(g)

At equilibrium, the concentration of N2O4 was found to be 6.01 x 10-6 mol/L. What is the concentration-based equilibrium constant (Kc) for this reaction at 25 oC?

I know the correct answer is 170, but I'd like to know how to get there. Thanks!

2. What is the pH of 3 mM H3PO4 solution? If you wish to adjust the pH of 1 L of that solution to 7.4, how much H+ or OH— do you need (in mmol)? At pH 7.4 what is the concentration of H2PO4 —? The pKas of H3PO4 are 2.1, 7.1 and 12.3.

Problem Title: Peptide Sequencing (Intro to Biochemichemistry)

#1:

Hydrolysis of dodecapeptide P with the enzyme trypsin affords the following fragments: Pro-Thr-Phe-Phe-Tyr-Ala-Arg, Asp-Asn-Arg, His-Arg.

Hydrolysis with chymotrypsin yields: Phe, Tyr, His-Arg-Pro-Thr-Phe, Ala-Arg-Asp-Asn-Arg.

What is the amino acid sequence of P? ___

________________

#2:

Hydrolysis of nonapeptide P with the enzyme trypsin affords the following fragments: Glu-Ser-Arg, Glu-Tyr-Ser-Phe-Ala-Arg.

Hydrolysis with chymotrypsin yields: Glu-Tyr, Ser-Phe, Ala-Arg-Glu-Ser-Arg.

What is the amino acid sequence of P? ___

Consider two solutions, the first being 50.0 mL of 1.00 M CuSO4 and the second 50.0 mL of 2.00 M KOH . When the two solutions are mixed in a constant-pressure calorimeter, a precipitate forms and the temperature of the mixture rises from 21.5 ∘C to 27.7 ∘C .

From the calorimetric data, calculate ΔH for the reaction that occurs on mixing. Assume that the calorimeter absorbs only a negligible quantity of heat, that the total volume of the solution is 100.0 mL , and that the specific heat and density of the solution after mixing are the same as that of pure water.

Using the data on gross (higher) heating values (HHV), estimate the mass of CO2 emitted per: 1) 1000 SCF of methane; 2) lb of gasoline; 3) ethanol; and, 4) No. 2 heating oil. Also express your answers in mass of CO2 per million Btu of each fuel.

predict the product of the hydrolysis of (s)-4-bromo-2-pentene

quick and easy to answer!
1. suppose you are working in a busy lab with multiple people sharing a given analytical balance. if you are weighing something which you will only have to weigh once, such as weighing out a reagent onto some weigh paper, which you immediately use to make a solution. is it OK to use the balance ' tare or zero function to set the vessel tare to zero? why or why not? if not what should be done instead?
2. now suppose you are weighing something thay you will have to weigh again later. for example suppose you are weighing out some sample into a crucible. later in the procedure you will heat the sample in the crucible to partially decompose it and you will need to know the mass of the material thay remains. is it OK to use the balance's zero fun tin to set the tare to zero? why or why not. if not what should you do instead.

A current of 5.42 A is passed through a Ni(NO3)2 solution. How long (in hours) would this current have to be applied to plate out 5.00 g of nickel? (Please show all steps)

As a technician in a large pharmaceutical research firm, you need to produce 350. mL of a potassium dihydrogen phosphate buffer solution of pH = 6.91. The pKa of H2PO4− is 7.21.

You have the following supplies: 2.00 L of 1.00 M KH2PO4 stock solution, 1.50 L of 1.00 M K2HPO4 stock solution, and a carboy of pure distilled H2O.

How much 1.00 M KH2PO4 will you need to make this solution? (Assume additive volumes.)

Express your answer to three significant digits with the appropriate units. Please show all steps.

What is a drying agent? When do you use it? What is the drying agent used in the lab? How much drying agent do you use? It has been suggested that drying agents can be collected after an experiment and the hydrated salt heated in an oven to drive off the water. The recycled drying agent can then be used again for another experiment. Is this a good idea? Give advantages and disadvantages of this proposal.

Give a breakdown on reduction and oxidation with relation to alcohols and the possible reagents that are used to do so.