Consider the reaction below and select the appropriate response for each mixture of reactants that follows. RESPONSES: LR = limiting reactant, XSR = excess reactant or stoichiometric quantities

2Ag + S → Ag₂S

a) 100 g Ag + 100 g S
b) 4.0 mol Ag + 2.0 mol S
c) 400 g Ag + 50 g S
d)15 atoms Ag + 10 atoms S

1. What mass of water is produced from the complete combustion of 3.10×10−3 g of methane?

2. What mass of oxygen is needed for the complete combustion of 3.10×10⁻³ g of methane?

3. Set up two algebraic equations, one expressing the mass of carbon dioxide produced in terms of each reagent and the other expressing the mass of sample burned in terms of each reagent.

What is the mass of methyl alcohol (CH3OH) in the sample?

The SN2 Reaction can be described as chemospecicific; define the terms "chemoselectivity" and "chemospecificity", and explain the origin of the observed chemospecifity in the williamson ether synthesis

Questions regarding the lab: Spectrophotometric Determination of Caffeine in a Soft Drink

1)How are the absorption spectra of atoms and molecules the same, and how are they different?

2)Beer’s law, A=e b c forms the basis of a calibration curve. It clearly shows that there is a theoretically linear relationship between absorbance and concentration under constant conditions of analyte absorptivity (e) and path length (b). However, it is important for an analyst to be aware that there are limitations analyte concentration range under which there truly is a linear relationship between absorbance and concentration. Under what conditions of concentration does the linear relationship break down?

3)Caffeine is not fluorescent. However, just for argument’s sake imagine that it was fluorescent. Would the wavelength of maximum fluorescence be shorter, longer, or equal to the wavelength of maximum absorbance? Why?

4)Why was it necessary to remove CO2 before the analysis?

Determine the percent composition of air in the lungs from the following composition in partial pressures: PN2=565mmHg, PO2=108mmHg, PCO2=37mmHg, PH2O=50mmHg; all at 37∘C and 1atm pressure.

A % N2

B % O2

C %CO2

D % H2O

Two common ways for a chemist to increase the yield of a reactiom are described below. Explain why they increase the yield.
a. Add more of one of the reactants
b. Remove one of the products as it is being made.

QUESTION 1

Compute the typical thermal energy of a water molecule at normal conditions: (k_B T) and compare it to the answer to an earlier problem, where you computed the work needed to lift a molecule by a certain distance. Based on this comparison, the thickness of the Earth's atmosphere is about

QUESTION 2

How much energy is released after an Argon atom moving with speed 3.00 km/sec hits a brick wall and get adsorbed?

QUESTION 3

In the previous problem, what is the value of the collision energy in terms of k_BT, assuming the temperature was 95 ^oF at the time?

QUESTION 4

In equilibrium, the number of molecules moving in one direction is equal, on average, to the number of molecules moving in the opposite direction.

True

False

QUESTION 5

In equilibrium, all directions in space are equivalent in that the speeds of molecules moving in any given direction have the same distribution.

True

False

a) Determine the rate law.

b) Calculate the rate constant. Specify units.

c) Calculate the rate of reaction for experiment 5.

d) How is the rate of appearance of D related to the disappearance of B?

e) In experiment 3, what is the rate of disappearance of B?

9. The decomposition of N₂O₅is first order with a rate constant of 4.80 x 10^-4 s^-1at 45 ºC. If the initial concentration is

1.65 x 10^-2 M, what is the concentration after 825 s? What is the half life? How long would it take for the concentration of N₂O₅ to decrease to 1.00 x 10^-2 M from its initial value?

10. The following reaction has a K_c = 3.92 at 1200 Kelvin:     CO(g) + 3H₂(g) ⇌ CH₄(g) + H₂O(g)

At equilibrium, the reaction vessel contains 0.30 M CO , 0.10 M H₂ , and 0.020 M H₂O

Write the equilibrium constant expression. What is the [CH₄] at equilibrium? Calculate the K_p (for atm).

answers:

9. 0.0111 M, 24.1 min, 17.4 min

10. K_c = [CH₄][H₂O]         [CH₄] = 0.059 M     K_p = 4.04 x 10^-4

               [CO][H₂]

A dilute solution of hydrochloric acid with a mass of 607.23 g and containing 0.33131 mol of HCl was exactly neutralized in a calorimeter by the sodium hydroxide in 614.70 g of a comparably dilute solution. The temperature increased from 15.848 to 19.739 °C. The specific heat of the HCl solution was 4.031 J·g^-1·°C^-1; that of the NaOH solution was 4.046 J·g^-1·°C^-1. The heat capacity of the calorimeter was 77.99 J·°C^-1.

Enter the balanced equation for the reaction. Include states in your answer.

Use the data above to calculate the heat evolved. What is the heat of neutralization per mole of HCl? Assume that the original solutions made independent contributions to the total heat capacity of the system following their mixing.
ΔH = ___ kJ/mol

1. What is oxidation?  How do you know if a molecule/atom has undergone oxidation.

2. Describe the reactivity of alcohols (1˚, 2˚, and 3˚) to oxidation.  

3. What are two ways besides IR that we can determine if we have the right product? Please explain what molecular property is measured and how borneol and camphor will show up differently in the technique.

4. When we take the IR of borneol and camphor, how will the spectra look different?

5. Why is the Camphor reaction considered “green”?

Calculate the pH of a buffer solution after the addition of 15.00 mL of 0.100 M NaOH to 50.00mL of the buffer that originally contains 0.100 M propanoic acid and 0.0750 M Sodium propionate. The Ka for propanoic acid is 1.3x10-5.

Problem 3 Grapefruit juice is known to effect drug oral bioavailability. Briefly describe the Grapejuice Effect on drug bioavailability

25.000 mL of 0.1438 M butanoic acid solution is titrated with 0.1247 M NaOH. Calculate the pH of titrant mixture at the following volumes of NaOH added. Ka butanoic acid = 1.52 x 10^-5

a.) 0.00 mL

b.) 16.04 mL

c.) 28.83 mL (Equivalence point)

d.) 30.30 mL

My answers were:

a.) 2.830

b.) 4.917

c.) 8.821

d.) 11.521