Chemistry Answers

Lithium crystallizes in a bcc structure with an edge length of 3.509 A. Calculate its density. What is the approximate metallic radius of lithium in picometers?

A 21.64 g sample of a nonreactive metal is placed in a flask containing 12.00 mL of water; the final volume is 13.81 mL. If the length of the edge of the unit cell is 387 pm and the metallic radius is 137 pm, determine the packing arrangement and identify the element.

What exists in a system that is at 1 atm and 175 K?

Two similar systems of monoatomic ideal gas named A & B. A undergoes isobaric changes when absorbed Q amount of heat and B undergoes isochoric changes when absorbed same amount of heat. Which system will be having higher temperature after absorbing same amount of heat? Justify your answer.   

If the frequencies of piston oscillation of two different steam engines are f1 and f2. If all other parameters remain same for them except the frequency, which engine is expected to do more work for the condition f1>f2. Justify your answer from the point of thermodynamics.   

1. Arrange the following according to decreasing melting point. Explain your answer.

A. sodium metal

B. sodium chloride

C. diamond

D. silicon di oxide

Calculate the chemical shift in parts per million for a proton that has resonance 128 Hz downfield from TMS on a spectrometer that operates at 60 Mhz

You are planning to prepare “salami-and-cheese sandwiches” for your friends. You need to slice the salami you bought for this purpose, and you will buy cheese in grams and bread in packages, each containing 24 loaves which are approximately 10 cm x 10 cm squares. You have adjusted the food slicer to cut 2.0 mm thick slices from the 0.18 m long salami you bought that is 100 mm in diameter.

a)  How many bread packages do you need to buy if each “salami-and-cheese sandwich” contains three slices of salami? (Hint: Your limiting reagent is salami)

b) You decided to add one 2.0 mm thick cheese slice to each sandwich from a cheese block which is a prism with a 3.5 in x 3.5 in square base. How much cheese (in grams) do you need to buy if its density is 1.093 g/cm³?

Find the weight of H2 stored in 100-cm3 cylindrical tank at 100

oC and 100 atm (10, 132.5 KPa)

using (a) Ideal gas equation (b) van der Waals equation if a = 0.244 atm-L

2

/mole

2 and b = 0.0266

L/mole. (Note: Use the method of successive approximation to solve for the mass of H2

)

Calculate the standard change in enthalpy for the given reaction:

2 Al(s) + Fe₂O₃(s) → Al₂O₃ (s) + 2 Fe(s)

Given:

ΔH° Fe₂O₃ (s) = -826 kJ/mol

ΔH° Al₂O₃ (s) = -1676 kJ/mol