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In the laboratory experimental determination of the standard heat of combustion of ethanol, the value obtained might be (1) Lower than expected due to incomplete combustion of the fuel (2) Lower than expected because some of the heat escape through the exhaust pipe (3) Lower than expected because the wick of the spirit lamp also burns.
N2(g)+3H2(g)⟶2NH3(g)
Assume 0.240 mol N2
and 0.749 mol H2
are present initially.
What mass (mg) of sodium chloride (FD1%=0.576) are required to make 226 ml of the following nose drop? (whole number mg)
0.18g Phenylephrine HCl (FD1% =0.185)
0.1g sodium metabisulphite (FD1%=0.386)
0.5g chorbutol (FD1%=0.14)
5ml propylene glycol (FD1%=0.262)
Purified water to 100ml
(a) Derive the expression (∂p/(∂V_m ) )_T in terms of R, T, a, and/or Vm.
(b) Derive the expression (∂p/∂T )_(V_m ) in terms of R, T, a, and/or Vm.
(c) Which of the above partial derivatives ((∂p/(∂V_m ) )_T and (∂p/∂T )_(V_m )) CANNOT have a negative value? Note that temperature is in Kelvin scale, and temperate cannot go below 0 K.
(d) Can the pressure p in the above equation of state be a state function? Namely, is the total differential dp exact? Show your detailed derivation.
a) The pKa of p-chlorobenzoic acid is 3.98; that of benzoic acid is 4.19.
i)
Calculate σ for p-Cl.
b) If ρ value for the alkaline saponification of methyl esters of substituted benzoic acids is 2.38, and the rate constant for saponification of methyl benzoate under the conditions of interest is 2.0 x 10-4
L mol-1 s-1, Calculate the rate constant of methyl m-nitrobenzoate.
c) Match the ρ values with the appropriate reactions. Explain your reasoning.
Reaction constants: + 2.45, +0.75, -2.3`9, -7.29
Reactions are:
i)
Nitration of substituted benzenes
ii)
Ionization of substituted benzenthiols
iii)
Ionization of substituted benzenephosphonic acids
iv)
Reaction of substituted N,N-dimethylaniline with methyl iodide
organic reactions; ensure the following are included in your discussion:
a) Derive the Hammett equation and define all the terms.
b) What is the significance of (ρ)-(rho), the reaction constant, sigma (σ), the substituent
constant in the Hammett equation.
c) Comment on meaning of positive and negative values of σ and ρ in the Hammett
equation.
d) Explain the conditions in which the σ+
, σ –
scale of values are used.
e) What is the application of the Hammett equation?
f) Hammett plots are not always linear; explain the meaning of their deviation from
linearity.
#340153 on Dec 2023