Other Chemistry Answers

0.0729g of analgesic powder are taken from an analgesic powder packet weighing 1.1456g. The 0.0729 g sample was dissolved in 50 mL of methanol. 2.5 mL of this 50 mL sample solution were run through a UV spectrophotometer. Through simultaneous equations it was determined that the concentration of Acetylsalicylic acid was 2.44 E-04 and the concentration of caffeine was 1.11484E-05. What are the concentrations of the two analytes (ASA and caffeine) in the original analgesic packet?

Among the molecules given below, identify those which are microwave
active. Justify your answer.
I2, HBr, CO2, CS2, NO

1. Answer in brief: (2×10=20)
i) The BF3molecule has a planar triangular structure with B at the centre. List the
symmetries of the BF3 molecule.
ii) In an orthorhombic crystal a lattice plane makes intercepts of 2a, 3b and 4c on the
three axes. Write down the Miller indices for this plane.
iii) Explain what type of bonding is expected to be observed in KCl.
iv) The energy of the lowest allowed level for an electron in a 1-D box is 10.0 eV.
Can the electron ever have an energy of 200 eV? Justify.
v) Show that the group velocity is zero at edge of the first Briclouin zone for a linear
monoatomic chain.

The net energy of a system of two atoms is given by E(r)= {(-A/r²) + (B/r⁸)} where r is p
the inter-atomic separation. If in a stable molecule the interatomic separation is 0.5
nm and the dissociation energy is 4.0eV, calculate the constants A and B.

The lattice constant for KCl is 6.292 Å and the Young’s modulus in the [100]
direction is 3.2×10¹⁰ Nm⁻² Calculate the force constant and the frequency at
which electromagnetic radiation is strongly reflected by the KCl crystal. The
atomic weights of K and Cl are 39 amu and 37 amu respectively. (Take
1 amu 1.67 10 kg).

1• a) The electrical conductivity of monovalent Na metal is 2.17×10⁷ Ω⁻¹m⁻¹. Calculate
the relaxation time and the drift velocity in a field of 100 V m⁻¹
. Take density of Na
to be 0.97 gm cm⁻³
.
b) A square lattice has a side of 3.2 Å. Calculate the momentum and energy of an
electron whose wave terminates at the boundary of the first Brillouin zone.

For an intrinsic semiconductor with a band gap of 0.75eV, calculate the effective
density of states for the electrons and the concentration of electrons in the
conduction band at T=300K, given that the effective masses of the electron and hole
are equal to the free mass of the electron.

What is the mass in grams of 5.00 × 1022molecules of C9H8O4?

taking oxygen concentration in the atmosphere and its solubility in water. find the expected concentration of carbon dioxide in water using its amount in the atmosphere as 390 ppm. then look at the actual carbon dioxide concentration and explain the difference due to the carbon dioxide chemistry.

When a given mass of Caco3 was heated 0.25dm3 of a gas was collected at 250 and at a pressure of 120Nm-2
1) Write an equation for the reaction
2) Calulate the mass of the gaseous product obtained from (ii) Caco3