Category Archives: chemistry

write down a ground state electronic configuration and indicate which electrons are core and which are valence

For each of the following atoms, write down a ground state electronic configuration and indicate which electrons are core and which are valence: (a) Na, (b) F, (c) N, (d) Sc. Draw energy level diagrams (see Fig. 1.15) to represent the ground state electronic configurations of the atoms in problem 1.26.

 

Write down the ground state electronic configuration of boron, and give a set of quantum numbers that uniquely defines each electron. Write down (with reasoning) the ground state electronic configurations of (a) Li, (b) O, (c) S, (d) Ca, (e) Ti, (f) Al. Draw energy level diagrams to show the ground state electronic configurations of only the valence electrons in an atom of (a) F, (b) Al and (c) Mg.

Calculate the compressibility factor for C, if one mole of it occupies 0.4 ltr at 300 K and 40 atm.

The mass of molecule A is twice that of molecule B. The root mean square velocity of molecule A is twice that of molecule B. If two containers of equal volume have same number of molecules, the ratio of pressure PA/PB will be

(a) 8 : 1 (b) 1 : 8 (c) 4 : 1 (d) 1 : 4

Calculate the compressibility factor for C, if one mole of it occupies 0.4 ltr at 300 K and 40 atm. Comment on the result.

(a) 0.40, C is more compressible than ideal gas.

(b) 0.65, C is more compressible than ideal gas.

(c) 0.55, C is more compressible than ideal gas.

(d) 0.62, C is more compressible than ideal gas.

compute the rate oxygen consumption by the cells in mm3 of  (STP) per hour.

The respiration of a suspension of yeast cells was measured by determining the decrease in pressure of the gas above the cell suspension. The apparatus was arranged so that the gas was confined to a constant volume, 16 cm3 and the entire pressure change was caused by uptake of oxygen by the cells. The pressure was measured in a monometer, the fluid of which had density of 1.034 g/c. The entire apparatus was immersed in a thermostat at 37°C. In a 30 mts observation period, the fluid in the open side of the manometer dropped 37 mm. Neglecting the solubility of oxygen in the yeast suspension, compute the rate oxygen consumption by the cells in mm3 of  (STP) per hour.

how many times does Sabu need to such out air in order to save Chacha Choudhary.

During one of his adventures, Chacha Chaudhary got trapped in an underground cave which was sealed 200 yrs back. The air inside the cave was poisonous, having some amount of carbon monoxide in addition to  and . Sabu, being huge could not enter into the cave, so in order to save Chacha Choudhary he started sucking the poisonous air out of the cave by mouth. Each time, he filled his lunge with cave air and exhaled it out in the surroundings. In the mean time, fresh air from surrounding effused into the cave till the pressure was again one atmosphere. Each time Sabu sucked out some air, the pressure in the cave dropped to half of its initial value of one atmosphere. If the initial sample of air from the….

Evaluate the claim, “The breath that you just took contains at least one molecule of air that was in the last breath of the Buddha, Siddhartha Gautama, who died about 400 b.c.e.” S

Evaluate the claim, “The breath that you just took contains at least one molecule of air that was in the last breath of the Buddha, Siddhartha Gautama, who died about 400 b.c.e.” See Problem 64 and assume complete mixing of Earth’s atmosphere over 2400 years.

Problem 64

Evaluate the claim, “There are more molecules in one breath of air than there are breaths in Earth’s entire atmosphere.” Use the following information. The total mass of the atmosphere is about 5.2 * 1021 g. The average molecular mass of air is about 29 u. An average breath has a volume of about 0.50 L and a density of about 1.3 g/L.

Write the structure for the quinoxaline derivative obtained when benzil is the reactant.

i.            1,2-Dicarbonyl compounds, such as benzil, can be characterized by reaction with o-phenylenediamine to form a substituted quinoxaline:

(a)    Write the structure for the quinoxaline derivative obtained when benzil is the reactant. Do you think this compound would be colored? If so, why?

(b)   Suggest a suitable mechanism for the formation of the quinoxaline compounds based on the reaction scheme shown above.

(c)    What reagent would you react with o-phenylenediamine to prepare the unsubstituted compound quinoxaline? Show a reaction scheme giving the structure of reactants and products.

v

i.            Alkynes can be hydrated in the presence of acid and HgSO4 by electrophilic addition of a molecule of water to the triple bond. The reaction proceeds by way of a carbocation intermediate. Hydration of acetylene (ethyne) produces acetaldehyde (ethanal). Outline the steps that occur in this transformation.

ii.            Use the IR tables (online and Chapter 8) to locate the absorption bands of the stretching frequencies of the alkyne  bond, alkyne  bond, and the alkene bond. Using these data, explain how you would distinguish between 1-butyne, 2-butyne, and 2-butene.

  What starting materials would you use to prepare each of the following compounds by the Diels–Alder reaction?

i.            What starting materials would you use to prepare each of the following compounds by the Diels–Alder reaction?

ii.            Diels–Alder reactions with benzene are rare, and require a very reactive (electron-deficient) dienophile, because benzene is a rather unreactive diene. Two are shown below. Give the structures of the product produced in each reaction.

iii.            Shown below are two heteroatom compounds that undergo the Diels–Alder reaction. Formulate the product obtained in each reaction.

Explain why the 25% NaOH solution is added to the reaction mixture.

i.            Explain why the 25% NaOH solution is added to the reaction mixture.

ii.            Draw a structure to illustrate the hydrogen bonding that may occur when two polymer molecules of this polyamide are cold – drawn together.

iii.            Predict the structure of the polymer that would result in the condensation of the following reactants. These monomers are used to produce the polyamide Nomex, a high-melting material used as an insulator in space shuttles and as the fire-resistant fabric in clothing worn in race cars.

iv.            Amides undergo hydrolysis to carboxylic acids on treatment with alkali. Diagram a suitable mechanism for the conversion of benzamide to benzoic acid using sodium hydroxide as the base.

Outline a simple chemical test that would distinguish between ethyl benzoate and benzamide (Hint: See Chapter 9).

i.            Offer an explanation of why 2,2,2-trifluoroacetic anhydride is more reactive toward aniline than acetic anhydride in the nucleophilic acyl substitution reaction presented in this experiment.

ii.            Offer a reasonable explanation of why acetamide has a higher melting and boiling point then N,N-dimethylacetamide even though it has a lower molecular weight:

iii.            Outline a simple chemical test that would distinguish between ethyl benzoate and benzamide (Hint: See Chapter 9).