An air bottle used for scuba diving breathing apparatus has a volume of 30 l. After it has been used, the pressure and temperature of the remaining air in the bottle are 0.3 MPa and 24 ◦C. Before the apparatus is used again, it is charged with air at temperature of 50 ◦C until the pressure in the bottle reaches 6 MPa. The charging processes is fast, and can be assumed to be adiabatic.

Questions: (a) Calculate the mass of air to be added to the bottle.

(b) What is the temperature of the air in the bottle at the end of the charging process?

1.687 g of N-2-acetamido-2-aminoethane-sulfonic acid potassium salt (ACES–K , MW = 220.29 g/mol) is dissolved in 90.76 mL of water. 15.18 mL of HCl is added to the solution, resulting in a pH of 7.25. Calculate the concentration of the HCl solution. The pKa of ACES is 6.85.

We ran a recrystallization experiment in lab, ultimtely I know recrystallization is used for purification purposes, but this question is confusing me.

What affect did recrystallization have upon the yield of product, the appearance of the product, and its melting point? yield and MP confuse me. I wasnt given the resources to check the MP during lab so is there a generalized consenssus of wha

I know you wont be able to tell me about appearance, I have that potion but the yield and MP portion I was wondering if there is some generalized assumption I am missing for recrystalllized products? I was not given the rousources to measure the MP during lab so I assume there is a trend I am missing from recrystallization - like raising the MP because it is a purer substance.

What is the advantage of using max wavelength rather than the wavelength nearby such as 580 nm?

This is for the Bradford protein assay where the maximum of the absorbance spectrum is at 595 nm.

When 2.3 g Co(NO3)2 is dissolved in 0.375 L of 0.44 M KOH, what are [Co2+], [Co(OH)42- ], and [OH- ]??? (Kf of Co(OH)42- = 5.0 109)

1. In preparation of common alum, why is it necessary to reduce the volume of your reaction mixture after the addition of sulfuric acid?

2. What was the whitish material that formed in the filter flask liquid after you began washing your product?

3. What was the purpose of washing your product with either ice-cold water or alcohol?

4. Why must the oven temperature be kept below 100 C when drying your product? (Two Reasons)

For the reaction 3O2(g) + 4NO(g)-->2N2O5(g)

the rate of change in concentration of O2, delta[O2]/deltat = 0.057 mol/L.sec. What is the rate of change of NO and what is the rate of change of N2O5? Show your calculations.

Compare the binding isotherm of normal hemoglobin (at pH 7.4, with 7.8 mM 2,3 BPG) with that of the following variations. For each variant, clearly explain why or why not the binding isotherm changes the way it does.

Explain Please!

a) Hemoglobin at pH 6.9, 7.8 mM 2,3 BPG

b) Hemoglobin in which a glutamate residue (at a position normally exposed to the solvent) has been substituted for a valine residue (at pH 7.4, with 7.8 mM 2,3 BPG)

c) Hemoglobin at pH 7.4 with 9.4 mM 2,3 BPG

d) Hemoglobin with a mutation in the beta chain position 94 (position FG1) (at pH 7.4, with 7.8 mM 2,3 BPG). In this mutation Asp94 ->His.

Calculate delta H rxn (at 500K) for the formation of 1 mol of ammonia gas. (show worked out solution)

When heated, ammonium carbonate decomposes as follows: NH4CO2NH2(s) ⇌ 2NH3(g) + CO2(g). At a certain temperature the equilibrium constant is K_P = 2.9 x 10^-3. Calculate the total equilibrium pressure at this temperature.

If the pH of a 1.00-in. rainfall over 1800miles2 is 3.40, how many kilograms of sulfuric acid, H2SO4, are present, assuming that it is the only acid contributing to the pH?

For sulfuric acid, Ka1 is very large and Ka2 is 0.012.

What is the effect of the following changes on the volume of 1 mol of an ideal gas? (Note: You should NOT need to do any explicit numerical calculations. Use your qualitative understanding of how volume depends on different experimental variables.)

1. The pressure is changed from 0.5 atm to 760 mm Hg (at constant temperature).

2. Another 3 mol of gas (to the existing one mol) is introduced through a stopcock (at constant temperature and pressure).

3. The pressure is halved and the temperature is changed from 0 °C to 546 K.

4. Another 1 mol of gas is introduced and the pressure is changed from 380 torr to 1 atm (at constant temperature).

5. The temperature is changed from -173 °C to 200 K (at constant pressure).

The answers are: the volumn quadrupled/doubled/halved/stays the same

Discuss the effect of (a) cholesterol addition, (b) free fatty acid addition, and (c) lysophospholipid addition to a membrane bilayer. Be sure to include an explanation of concentration dependence in biochemical and physical terms. Will your answers to (b) or (c) change if you consider saturated versus unsaturated fatty acids?

Aspartate transcarbamoylase (ATCase) catalyzes the first step in the biosynthesis of a nucleotide. The end product of the pathway, cytidine 5’-triphosphate (CTP), in turn inhibits ATCase activity. This effect can be overcome by the addition of ATP.

a) Sketch the enzyme activity curve of ATCase alone, ATCase + CTP, & ATCase + ATP. Explain your rationale.

b) The regulation of ATCase activity by CTP exemplifies what TWO types of regulation?