polycondensation reaction takes place between 1.2 moles of a dicarboxylic acid, 0.4 moles of glycerol (a triol) and 0.6 moles of ethylene glycol (a diol). A. Calculate the critical extents of reaction for gelation using (i) the statistical theory of Flory and (ii) the Carothers theory. B.Comment on the observation that the measured value of the critical extent of reaction is 0.866.

(a). (I). 0.816; 0.816

(ii). 0.917.

(b). When the value for the critical extent of reaction is 0.866, then the number of moles of glycerol and the number of moles of di-carboxylic acid is the same. But, in this case the number of moles of glycerol is not the same with the number of moles of di-carboxylic acid.

Explanation:

So, without mincing words let's get straight into the solution to the question above.

(a). Using the (i) statistical theory of Flory to Determine the critical extent of reaction gelation, one has to make use of the two equations given below;

P(1) = [ v + vb ( n - 2)^-1/2 (1).

P(2) = v^1/2 [ 1 + b ( n - 2)^-1/2 (2).

The value for v = 1.2 + 1.2/ 1.2 × 2 = 1.

The value of b = (1.2 + 1.2)/ 1.2 = 0.5.

Thus, putting the values into the equation (1) and (2) above gives;

NB: n = 3.

P(1) = [ 1 + 1 × 0.5 ( 3 - 2)^-1/2 = 0.816.

P(2) = 1^1/2 [ 1 + 0.5 ( 3 - 2)^-1/2 = 0.816.

Using the (ii) carother's theory to Determine the critical extent of reaction gelation.

We have the following values for glycerol: k = 0.4, n = 3.

For ethylene glycol; k = 0.6, n = 2.

Therefore, the critical extent of reaction gelation =2/[ (0.6 × 2) + (0.4 × 3) + (1.2 × 2)/ (0.6 + 0.4 + 1.2)] = 2/ 2.18 = 0.917

(b). When the value for the critical extent of reaction is 0.866, then the number of moles of glycerol and the number of moles of di-carboxylic acid is the same. But, in this case the number of moles of glycerol is not the same with the number of moles of di-carboxylic acid.

a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -

1. measurement of atmospheric pressure  

2. determining the altitude of a place

3. weather forecasting

4. calibration and checking of aneroid barometers

5. application in fluid mechanics

6. measurement of pressure in aircrafts

7. surface weather analysis

8. preparation of barographs

9. usage in physical sciences like physics, astronomy & chemistry

10. preparation of aircraft altimeters

characteristics of mercury barometer : -

1.used to define and measure atmospheric pressure.

2.on the average at sea level the column of mercury rises to a height of about 760 mm.

3.this quantity is equal to 1 atmosphere.

4.it is also known as standard atmospheric pressure.

5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.

no statements shown

the atomic number of carbon is six, which means that a carbon atom has six protons. carbon has three naturally occurring isotopes: carbon-12, carbon-13, and carbon-14. which of these statements are true about carbon and its isotopes? select all that appl