What are chemicals? List three chemicals and explain how they may be beneficial or detrimental to humans or the environment.

Indicate whether the entropy of the system increases, decreases, or is unchanged for each of the following processes:

a) water evaporates at room temperature

b) a gas condenses at its normal boiling point

c) cold water is heated to 120 F by a natural gas heater

d) water vapor forms ice crystals (frost) on your car's windshield

e) CH4(g) + 2O2(g)<----> CO2(g)+ 2H2O(l)

The Ka of a monoprotic weak acid is 8.6x 10-6, what is the pH of a 0.38 M solution of this acid?

Calculate the percent ionization of propionic acid (C2H5COOH) in solutions of each of the following concentrations (Ka is given in Appendix D in the textbook). Ka=1.3*10^-5 Part A 0.250 M . Express your answer using two significant figures. Part B 7.72×10−2 M . Express your answer using two significant figures. Part C 1.92×10−2 M .

Determine the molar enthalpy of neutralization(DeltaHneutralization); where, Volume of HCl=100mL, Molarity of HCl=2.00M, Volume of NaOH=100mL, Molarity of NaOH=2.00M, Average initial temperature of acid and base=22.50 C, Final temperature=35.50 C, Heat capacity of the calorimeter (Cp)= 50 j/K.

Using 1.0 nM enzyme X for the enzyme kinetics experiments, you obtained the reaction rates at different concentrations of substrate (shown in the following table). Assume that the enzyme X follows a typical Michaelis-Menten kinetics.

[substrate] (μM) Reaction rate (μmol/min)

2 7

5 17

10 29

20 44

50 67

100 80

200 89

500 95

1000 98

a) Estimate the Vmax and Km values of the enzyme in this reaction using double reciprocal plot.

b) If 5.0 nM of the enzyme X is used in the experiment, what will be the Vmax and Km of the enzyme X?.

An electron in a Hydrogen atom originally at n=5 energy level absorbs a photon with a frequency of 6.54×10^13 and then proceeds to emit another photon with a frequency of 2.98×10^14. To what energy level does the electron move?

: Let’s consider second-law thermodynamics again, we define S_univ=S_sys + S_surr

1. Explain the physical meaning of three symbols here: S_univ, S_sys , S_surr

2. Which of these three determines if a proposed process is spontaneous or not? State what sign it needs to be for the proposed process to be spontaneous?

What difference in the properties of 0.1 M HCl and 0.1 M acetic acid caused the pH's of equal volumes of each to differ?

What is the percent water by weight of lithium perchlorate trihydrate?

1. An enzyme has a molecular weight of 25,000. If V_max= 80umol/min and you use 500uL of a 1mg/mL solution of enzyme, what is the turnover number?

2. In an enzyme activity assay, a 100uL assay sample containing 3.2 x 10^-5 M enzyme produced an absorbance change per minute of 0.42. The molecular weight of the enzyme is 17,000 g/mol and the extinction coefficient is 6220 M^-1 cm^-1.

What is the activity of the enzyme?

What is the specific activity of the enzyme?

1. Glucose has a solubility of 125 g /100 mL. What is the approximate concentration of glucose in a
saturated solution? How much glucose can be dissolved in 745 mL of water?
[glucose] _________ M
Glucose _________ g
2. Determine whether the following salts or molecules will have higher or lower solubility in water
at higher temperatures.
KCl(s) + H2O(l) KCl(aq), ?Hrxn > 0 __________
NH3(g) + H2O(l) NH3(aq), ?Hrxn< 0 __________
3. BaF2 has a Ksp of 2.45 x 10-5. What is the solubility of BaF2? What is the F-
concentration in a
saturated barium fluoride solution?
Solubility of barium fluoride ___________
[F-]= _______

Discuss how screening can be used for mass spectra