Chemistry, 15.10.2019 05:00 alaj6878

A75 um thick polysulphone microporous membrane has an average porosity of e 0.35. pure water flux through the membrane is 35 m'/m h at a pressure drop of 2 bar at 25°c. the average pore size is estimated to be 0.8 um. calculate the tortuosity factor of the pores, the resistance to flow offered by the membrane and its water permeability. the viscosity of water at 25°c is 0.9 cp

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Answer from: kingdrex8226

Explanation:

The given data is as follows.

Water flux, $J_{w}$ = 25 $m^{3}/m^{2}h$

= $\frac{25}{3600} m^{3}/m^{2}h$

So, let velocity (u) = $\frac{25}{3600}$ m/s = $6.9 \times 10^{-3}$

$\rho$ = 998 $kg/m^{3}$

Pore size, d = $0.8 \times 10^{-6} m$

$\mu$ = 0.9 cP = $9 \times 10^{-4}$ Pa.s

Hence, calculate the reynold number as follows.

$R_{e} = \frac{\rho \times u \times d}{\mu}$

= $\frac{998 kg/m^{3} \times 6.9 \times 10^{-3} \times 0.8 \times 10^{-6} m}{9 \times 10^{-4} Pa.s}$

= $612.1 \times 10^{-5}$

= 0.006

This means that the flow is laminar.

Now, we use Hagen-Poiseuille equation as follows.

$J_{w} = \frac{\varepsilon \times d^{2}}{32 \times \mu \times \tau} \times \frac{\Delta P}{L_{m}}$

where, $\varepsilon$ = membrane porosity = 0.35

d = $0.8 \times 10^{-6}$ m

$\Delta P$ = $2 \times 10^{5} Pa$

$\mu$ = $9 \times 10^{-4}$

$\tau$ = tortuosity

$L_{m}$ = membrane thickness = $75 \times 10^{-6} m$

$\frac{25}{3600} = \frac{0.35 \times (0.8 \times 10^{-6})}{32 \times (9 \times 10^{-4}) \times \tau}$

$\tau$ = 3.73

Hence, the tortuosity factor of the pores is 3.73.

As flow resistance = $R_{m}$

$J_{w} = \frac{\Delta P}{r \times R_{m}}$

$R_{m} = 3.2 \times 10^{10} m^{-1}$

Water permeability is represented by $L_{p}$ .

$J_{w} = L_{p} \times \Delta P$

$6.9 \times 10^{-3}$ = $L_{p} \times 2 \times 10^{5} Pa$

$L_{p} = 3.45 \times 10^{-8} m^{3}/m^{2}s Pa$

Therefore, the resistance to flow is $3.2 \times 10^{10} m^{-1}$ and its water permeability is $3.45 \times 10^{-8} m^{3}/m^{2}s Pa$ .

Answer from: Quest

Answer:

a. energy is absorbed in the reaction.

explanation:

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.

Answer from: Quest

c is having 4 valence electrons and is bonded to three hydrogens and one sulphur atom, therefore, the number of bond pair is equal to four. as all the valence electrons are used in forming the bonds so, there is no lone pair left on carbon.

s is having 6 valence electrons and is bonded to one other sulfur atom and one carbon atom, therefore, the number of bond pair is equal to 2. as only two valence electrons are used in forming the bonds so, four electrons are left. therefore, two lone pairs are present on s.

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