If water is pure enough and in a sufficiently smooth container, it can sometimes be “supercooled” so that it remains liquid for a time even when its temperature is lowered below its freezing point. (For this problem, you can use table 8.2 for heat capacities and may assume that they do not change with temperature.)

(a) A beaker with 500 g liquid water initially at 10 ºC is placed in a freezer at –15 ºC, where the liquid supercools until it is at the same temperature as the freezer. Calculate qH2O, and pay careful attention to its sign.

(b) The heat of fusion of ice at 0 ºC is 6.01 kJ/mol (Table 8.3), but this number changes slightly with temperature. Calculate the heat of fusion of ice at –15 ºC.

(c) The beaker of water from part (a) (now at –15 ºC) is taken out of the freezer and jostled, which triggers the water to freeze rapidly (so quickly that the beaker is effectively insulated; no heat is transferred to or from the beaker’s surroundings). As the ice forms, heat is given off and so the temperature of the water/ice mixture rises until it reaches 0 ºC, at which point no more ice forms. How much ice will form during this process?

1) A) A samole of flourine gas is in a 12.56 L cylinder at 41.35 degree celsius and 700 torres. What is the kinetic energy and the root mean square velocity of the flourine gas.

B) Methane gas diffuses at a rate of 32.25 ml/min. Under identical conditions an unknown gas diffuses at a rate of 22.28 ml/min. What is the molar mass of the unknown gas.

C) Oxygen IS produced by the decomposition of sodium bromate and collected over water. if 76.25 ml of wet oxygen is collected at 47.5 degree celsius with an atmospheric barometric pressure of 697.2 mmHg. How many milligrams of sodium bromate have been consumed?

D) Rank the following gases from most ideal to least ideal.

IF₃ CH₄ SF₆

Calculate the pH at the equivalence point for the titration of 0.614 M B: (a weak base with pKb = 4.13) with 0.614 M HCl.

Calculate the pH at the equivalence point for the titration of 1.328 M HA (a weak acid with pKa = 6.95) with 1.328 M NaOH.

2A. The label on a 1.00-L bottle of wine states that the alcohol content is 12.5% (v/v). How much alcohol is present in the bottle?

2B. How do you make 2.50 L of 3.25 M NaHC03?

2C. How do you make 2.50 L of 0.200 M NaOH?

2D.Tell the type of solution(solid-in-liquid, etc) represented by each of the following: Gasohol, Wax in gasoline, and Gas mixture used as anesthesia

1. What is a peptide bond? 2. How does the primary structure of proteins differ from the secondary structure? A. Peptide Bonds A.1 Structure of glycylserine Structure of serylglycine A.2 Hydrolysis of serylglycine

Q.1 Why are heat and alcohol used to disinfect medical equipment?

Q.2 Why is milk given to someone who accidentally ingests a heavy metal ion such as silver or mercury?

Q.5 After working with HNO3, a student noticed that she had a yellow spot on her hand. What might be the reason?

Q.6 Which samples above give a negative biuret test? Why?

Q.7 What functional group gives a positive test in the xanthoproteic test?

Q.8 What tests could you use to determine whether an unlabeled test tube contained an amino acid or a protein?

One of the substances (ethylene glycol) appeared to increase in temperature as it evaporated (Change in temperature upon complete evaporation: +1.4). How can this be the case? What alteration to the experiment could have been done to test and see if this evaporation could be exothermic or did that liquid even evaporate at all?

What is the pH of a 0.445 M ammonia solution? Express your answer numerically to two decimal places.

Consider the reaction of NH3 with water:
NH₃ + H2O ↔ NH₄⁺+ OH^-
(Kb=Kw/Ka)

and also
NH₄+ H2O ↔ NH₃ + H3O⁺ (Ka = 5.70×10-10)

Including the ICE Tables:

a) Find the pH of 50.00 mL of 0.200M NH3 after the addition of 45.00 mL of 0.200M HCl.

b) Find the pH of 50.00 mL of 0.200M NH3 after the addition of 50.00 mL of 0.200M HCl.

c) Find the pH of 50.00 mL of 0.200M NH3 after the addition of 55.00 mL of 0.200M HCl.  

Benzoic acid is a weak acid that has antimicrobial properties. Its sodium salt, sodium benzoate, is a preservative found in foods, medications, and personal hygiene products. Benzoic acid ionizes in water:

C6H5COOH⇌C6H5COO−+H+

The pKa of this reaction is 4.2. In a 0.57 M solution of benzoic acid, what percentage of the molecules are ionized?

Express your answer to two significant figures and include the appropriate units.

25.0 mL of a 0.0450 M butylamine solution is extracted with 105 mL of solvent. The partition coefficient for the reaction is 2.00 and the pKa of the protonated form of butylamine is 10.640. Calculate the concentration of butylamine remaining in the aqueous phase at pH = 9.80 and pH = 12.1.

Isolation and characterization of the enzyme alkaline phosphate from escherichia coli: protein purification.

2) why is it necessary to dialyze the enzyme after ammonium sulfate precipitation?

Why are aryl and vinyl beta eliminations rare.

A 14.585 g sample of CaCl2 was added to 12.283 g of K2CO3 and mixed in water. A 3.573 g yield of CaCO3 was obtained.

(1) What is the limiting reagent?

(2) Calculate the percent yield of CaCO3.