Physical Chemistry Answers

Assume an enzyme system, which contains a substrate, and reacts accordingly
known Michaelis-Menten mechanism. Measurements are performed at a given temperature with
substrate S and S*
(isotopically substituted substrate).
a) Measurements were performed with both substrate S and substrate S*
, separately. Give the ratios of the velocities of the two above cases (u / u*) in very small and
very large concentrations of substrates, respectively, as a function of Km and k2.
(Note: Assume that initially [S] = [S*] and [E] are common.)
b) Then assume that the study of the two substrates is done simultaneously, ie the
competing isotopic phenomena. Return the ratios of the speeds of the two again
cases in the two marginal cases, ie very small and very large concentrations of substrates. (Note: Apply steady-state management to
[ES] and… assume that initially [S] = [S*]. )

Iodine-131 is a radioisotope with a half-life of 8 days and can be used in the treatment of thyroid cancer. Calculate the percentage of iodine-131 that would have decayed after 24 days

A 0.1 molar solution of NaCl is isotonic with 1% urea solution. To find out the van't Hoff factor and degree of ionisation of NaCl.

The vapour pressure of an aqueous solution containing 28% by mass of liquid A( molar mass=70gmol⁻¹) is 2.4×10⁵Pa at 360K. To find out the vapour pressure of pure A if that of pure water is 0.88×10⁵Pa.

A sample of water was alkaline to both phenolphthalein and methyl orange.100 ml of this water sample required 10ml of N/50 h2so4 for phenolphthalein end point.determine the type and extent of alkalinity present

1. If a sample of gas of volume 605 mL and temperature of 39 0C, has 0.00803 moles. What is  its pressure?

                    [ R = 0.08021 Latm/Kmol ]

The specific heats of some elements at 25°C are as follows: aluminum = 0.215 cal/g⋅°C; carbon (graphite) = 0.170 cal/g⋅°C; iron = 0.107 cal/g⋅°C; mercury = 0.0331 cal/g⋅°C.

a) Which element would require the smallest amount of heat to raise the temperature of 100. g of the element by 10.°C?

b) If the same amount of heat needed to raise the temperature of 1 g of aluminum by 59°C were applied to 1 g of mercury, by how many degrees would its temperature be raised? deltaT Hg= ............... Celises

c) If a certain amount of heat is used to raise the temperature of 1.6 g of iron by 10.°C, the temperature of 1 g of which element would also be raised by 10.°C, using the same amount of heat?

-aluminum

-carbon (graphite)

-mercury

The pressure was exerted with a piston on molted naphthalene (C₁₀H₁₈) at 95 ^oC. The vapour pressure of naphthalene under 1.0 bar is 2.0 kPa and its density is 0.962 g cm^-3, calculate the normal boiling point.

An environmental chemist needs a carbonate buffer of pH 10.0 to study the effects of the acid rain on limestone-rich soils. How many grams of Na₂CO₃ must she add to 1.5L of freshly prepared 0.20M NaHCO₃ to make the buffer? k_a of HCO₃^- is 4.7 x 10^-11.

100 ml of a raw water sample on titration with N/50 H 2 SO 4

required 10 ml of the acid to phenolphthalein end point and

another 10 ml of the acid to methyl orange end point. Determine

the type and extent of alkalinity present in the water sample.