Materials:

Reaction Buffer 0.5 M Tris HCl pH 8.0 with 5 mM MgCl2

Alkaline phosphatase: 500 μg/mL stock solution in the buffer above. Keep enzyme on ice!

p-nitrophenyl phosphate: 1000 μM and 10000 μM stock solutions in reaction buffer

1) Using the enzyme stock solution above and the dilution equation, calculate the volumes needed to prepare 2 mL of three enzyme dilutions consisting of 100 μg/mL, 125 μg/mL, and 150 μg/mL. Use the reaction buffer to make these dilutions.

2) Calculate the amount of substrate needed for each of the following concentrations 10 μM, 25 μM, 50 μM, 100 μM, 200 μM, 500 μM, 1000 μM, and 2000 μM using the two stock solution concentrations listed above. Use the 1000 μM stock solution to calculate dilutions from 10-200 μM and the 10,000 μM stock solution to calculate from 500 μM-2000 μM. The final volume is 1.0 mL (or 1000 μL) for each dilution. Also calculate the volume of buffer needed, given that we will add 100 μL of the enzyme solution and the final volume is 1.0 mL (or 1000 μL) for each dilution.

What is the final pH at 25°C when 56 mL of 0.139 mol/L NaOH(aq) and 30 mL of 0.187 mol/L HA(aq) are mixed. Assume that HA is a weak monoprotic acid with pKa = 4.99 at 25°C

Part B

What is the pH after 0.150 mol of HCl is added to the buffer from Part A? Assume no volume change on the addition of the acid.

Express the pH numerically to three decimal places.

Part A What is the pH of a buffer prepared by adding 0.809 mol of the weak acid HA to 0.507 mol of NaA in 2.00 L of solution? The dissociation constant K a of HA is 5.66× 10 −7 . Express the pH numerically to three decimal places

A) Calculate the concentration of all species in a 0.490 M solution of H2SO3.

B) Calculate the concentration of all species in a 0.165 M solution of H2CO3.

Preparation of Ammine Complexes of Cobalt(III)

1) Give at least two differences between the two preparations that are carried out in this lab.

2) Base on the structures of complex ions shown in this lab, draw a pictures od what you think the complex ion [Fe(NH3)6]+2 would look like.

3) Suggest another small molecule that, like water and ammonia, might make a good ligand. Remember that ligands are electron pair donors, which means that one atom must have a lone pair of electrons on it. Draw the Lewis dot structure of the molecule you think would make a good ligand.

4) How would your percent yield be affected if you didn't dry your product completely? Explain your answer.

5) Why do you think both reaction mixtures were cooled before the products were collected by filtration?

6) What was the purpose of the hydrogen peroxide used in this lab?

7) What might have happened if the temperature of the oven were set to 210 Celsius instead of 110 Celsius called for in the procedure?

P23-27: Molar absorptivity data for the cobalt and nickel complexes with 2,3-
quinoxalinedithiol are εCo = 36,400 and εNi = 5520 at 510 nm and εCo = 1240 and εNi = 17,500 at 656 nm. A 0.425-g sample was dissolved and diluted to 50.0 mL. A 25.0-mL aliquot was treated to eliminate interferences; after addition of 2,3quinoxalinedithiol, the volume was adjusted to 50.0 mL. This solution had an absorbance of 0.446 at 510 nm and 0.326 at 656 nm in a 1.00-cm cell. Calculate the parts per million of cobalt and nickel in the sample.

The average human body contains 5.50 L of blood with a Fe2+ concentration of 2.20×10−5 M . If a person ingests 9.00 mL of 21.0 mM NaCN, what percentage of iron(II) in the blood would be sequestered by the cyanide ion?

3. (a) What is SDS (sodium dodecylsulfate)? Draw the structure

(b) How would you separate a mixture of polypeptides according to their lengths using SDS –

polyacrylamide gel electrophoresis? Describe in a few sentences.

To 1.0 L of water, 2.8 × 10^–6 mol of Pb(NO₃)₂, 6.6 × 10^–5 mol of K₂CrO₄, and 1.0 mol of NaCl are added. What will happen?

A.No precipitate will form.

B.A precipitate of PbCrO₄ will form.

C.Both a precipitate of PbCl₂ and a precipitate of PbCrO₄ will form.

D.A precipitate of PbCl₂ will form.

E.A precipitate of KCl will form.

Calculate the pH for each of the following cases in the titration of 25.0 mL of 0.230A pyridine, C5H5N(aq) with 0.230M HBr(aq):

a.) before addition of any HBr

b.) after addition of 12.5 mL of HBr

c.) after addition of 20.0 mL of HBr

d.) after addition of 25.0 mL of HBr

e.) after addition of 36.0 mL of HBr

This is for my biochemistry lab, the experiment is dealing with trypsin and BPTI. I need to make a graph: plot the absorbance change per minute versus the BPTI concentration for each cuvette.

here are my cuvettes and amount of BPTI added to each

1- 0uL BPTI added

2- 10 uL BPTI added

3-20 uL BPTI added

4-30 uL BPTI added

5- 40 uL BPTI added

6- 50 uL BPTI added.

Each cuvette has a different amount of water and trypsin added to them, for a total volume of 100 uL in each cuvette.

I was give a sample of BPTI for which I had to find the concentration. Using the absorbance, I calculated that the concentration was 0.035mM. We then had to dilute this 10-fold, so to 0.0035mM.

I am not sure how to find the concentration of BPTI in each cuvette with this information. The molecular weight of BPTI is 6500. I don't know if that is needed.

I feel like this should be really easy, but I am having trouble doing this.

A single charcoal briquette has a mass of 0.1 kg, and is made up of almost entirely carbon. I want to burn that briquette in air in a sealed oven. When the combustion is complete, the gases in the oven will include CO2, O2, and N2, and the mole fraction of CO2 in this exhaust is 5%. How much air is needed (before the combustion)? Give your answer as kg, kg mole, and as a volume in m3 . Assume that p = 1 atm, and T = 400 ˚C

determine the pH of each two component solution

a.) 0.550 M HI and 0.850 M HF

b.) 0.112 M NaCl and 0.953 M HF

c.) 0.050 M KOH and 0.015 M Ba(OH)2

d.) 0.088 M HClO4 and 0.022 M KOH

Part A

It takes 55.0 J to raise the temperature of an 10.2 g piece of unknown metal from 13.0∘C to 25.0 ∘C. What is the specific heat for the metal?

Part B

The molar heat capacity of silver is 25.35 J/mol⋅∘C. How much energy would it take to raise the temperature of 10.2 g of silver by 15.4 ∘C ?

I got 36.9 J for B and its correct

Part C

What is the specific heat of silver?