Chapter 16 General questions and heterogeneous chemical reactions page 16-1
Chapter 16 General questions and heterogeneous chemical reactions
1. Solubilization of linoleic acid
For the solubilization of linoleic acid from spinning disc, we use eq. 16.3-7,
(2.04e-5Re1/2)-1 (s/cm)
The intercept is 1514 (s/cm) = 1/2
2. Oxidation of Ce3+
For the oxidation of Ce on the Pt surface, the total mass transfer coefficient is
3. Surface electrochemical reaction of Fe2+
For this type of heterogeneous reaction,
The correlation between flux and current density is
4. Growing of a KCl crystal
For forced convection around sphere, from Table 8.3-3,
D = 2 + 0.6Re Sc
For KCl in water, D = 1.99410-5 cm2/s
1.99410-5
0.063
0.063*1.2*6
0.0105
1/2
0.0105/1.2
1.99410-5
1/3
The flux is j1 = 0.0013*1.984/60 = 4.310-5 g/cm2-s
5. Cu-Si reaction
(a) Mass balance at the interface
Growth rate of the Cu3Si layer = Diffusion rate of Cu
6. Intestinal transport
(a) j1 = k(c1 – c1i) = vmaxc1i
Km + c1i
Chapter 16 General questions and heterogeneous chemical reactions page 16-3
1/c1
1/j1
1/vmax
max
1
K
m
slope =
In parallel, for the simplified equation, we realize that at large (1/c1),
Ka (2)
and at small (1/c1), j1 = vmax
Both will give the same plot.
(b) Winne’s equation:
By comparing Eq. (1) and (2), we have
Obviously, this is different from “Winne’s equation.”
7. Mass transfer with cracking
For the surface reaction of c1i
2c2i
(a) For a thin film near surface, the boundary conditions are
(b) For concentrated mixture, n1 = –Ddc1
dz + c v
10
where v0 = (n1 + n2)/c, but n2 = -2n1
Thus v0 = –n1/c
(c) Integration gives
c1i + c
l
c – c10
c = D
l (c10 – c1i)
8. Mass transfer of BaO with reaction
Chapter 16 General questions and heterogeneous chemical reactions page 16-4
Mass balance in the ceramic: diffusion flux = reaction rate
9. Interfacial resistance of a molecularly compact interfacial film
The result is like that for a heterogeneous reaction given in Eq. 16.3-6 and 16.3-7:
k1 + 1
k2 + k-2
k2k3
In the common case, k2 and k-2 are very large, so this reduces to Eq. 8.5-8 to 8.5-12, but with
(k2/k-2) equivalent to the partition coefficient, H. In the exceptional case where k2 is slow, or k-2
is zero, this reduces to the case discussed in Ex. 16.3-2.
10. Mass balance on the hydrate layer
Accumulation rate of the hydrate layer = Diffusion rate of water
11. Air hydrate
For an approximate solution, make a pseudo-steady state mass balance
hydrate accumulation = water diffusion across hydrate
where R and r are the initial and present bubble radii, respectively; k is a mass transfer
coefficient equal to D
R – r; and and are hydrate and water densities, assumed equal.
H H2O
Chapter 16 General questions and heterogeneous chemical reactions page 16-5
Therefore the bubble is gone when
From the values given, at -46°C,