Method & Calculations for Preparation of Chemical Solutions

QUESTION #1

For dyeing 250gms of textile  material with 2% shade, how much amount of dye powder is required ?

2% shade means 2gms of dye powder for dyeing of 100gms of material,

therefore, for 100gms of material –> 2gms of dye powder

       then, for 250gms of material –> 250*2/100 = 5gms of dye powder is required

Therefore, 5gms of dye powder is required for dyeing 250gms of textile material with 2% shade.


QUESTION #2

How will you prepare 100ml 70% (w/w) H2S0Solution, where density of H2S04 is 2gm/cc ?

70% (w/w) of H2S04 means 70gms of H2S04 and 30gms of water.

Therefore, 70gms of H2S04 contains –> 70/Density of H2S04 = 70/2 = 35ml of H2S04

Since, H2S04 is not available at 100% conc, so assuming available conc. to be 98%

Of 100% conc. –> 35ml is required

then of 98% conc.  –> 98*100/35 = 35.71ml is required (inversely proportional)

Since density of water is 1gm/cc, therefore 30gms of water = 30/1 = 30ml of water

Now, total volume = 35.71 + 30 = 65.71 ml

means, 65.71ml of 70% (w/w) H2S04 soln contains = 35.71 ml of H2S04

Therefore, 100ml of 70% (w/w) H2S04 soln will contain = 35.71*100/65.71 = 54.35 ml of 98% H2S04

Therefore, to prepare 100ml of 70% (w/w) H2S04, 54.35 ml of 98% H2S04 and 45.65 ml of water is to be used.


QUESTION #3

For dyeing 3Kgs of cotton 150gms of dye was taken. During dyeing, only 120 gms of dye went on the cotton material. Calculate the % Shade and % Exhaustion for this dyeing ?

For dyeing 3Kg of cotton, 150gms of dye was taken, since 3kg = 3000gms;

Therefore, for dyeing 3000gms of cotton –> 150gms of dye was taken

Therefore for 100gms of cotton  –> 100*150/3000 = 5gms of dye should be used.

Therefore, the % Shade for this dyeing is 5%

Now for calculating % Exhaustion we know that from 150gms of total dye used for dyeing, only 120gms of dye went on the cotton material, now by expressing this as a percentage will give the % Exhaustion for this dyeing as follows,

% Exhaustion = (amount of dye transferred / amount of dye taken) * 100

                     = (120 / 150) * 100 = 80%

Hence, the % Exhaustion for this dyeing is 80%


QUESTION #4

200Kg of fabric is dyed with 2% shade. During dyeing, 3kg of dye goes on fabric. Calculate % Exhaustion ?

The weight of material is 200kg = 200000gms

% Shade of fabric is 2%,

i.e., for 100gms of fabric, 2gm of dye is required

Therefore, for 200000gms of fabric –> (200000*2/100) = 4000gms of dye is required

= 4 Kgs

Now, since 4kg of dye was used out of which only 3 kg of dye is transferred on the fibre

Therefore, % Exhaustion = (amount of dye transferred / amount of dye taken) * 100

= (3 / 4) * 100 = 75%

Therefore, the % Exhaustion for this dyeing is 75%


QUESTION #5

For Scouring 100gm of Cotton use 3g/l of NaOH and 2% owm Detergent keeping MLR 1:50,

Available conc. of NaOH = 9% (90gpl)

Availabale conc. of Detergent = 20%

Calculate the amount of detergent and NaOH soln and water to be taken.

W = 100gms

MLR = 1:50

V = 100 * 50 = 5000ml

Therefore amount of NaOH to be taken = V*P/C = 5000*3/90 = 166.67ml

Now, the amount of detergent to be used = W*P/C = 100*2/20 = 10ml

Amount of water  = Total volume of Liquor – Total amount of chemicals

= 5000ml – (166.67ml +10ml)

= 4823.33ml of water

Therefore, the amount of Water to be used is 4823.33ml


QUESTION #6

For Bleaching of 200gm of Cotton use 3g/l bleaching solution and 2% NaOH (owm). MLR is 1:30. Available conc. of Bleaching soln. = 3% and NaOH is 20g/l.

Calculate the amount of chemicals and water to be taken.

W = 200gms

MLR = 1:30

V = 200*30 = 6000ml

Amount of NaOH to be used = W*P/C = 200*20/20 = 200ml

Amount of Bleaching solution to be used = V*P/C = 6000*3/30 = 600ml

T = Total amount of chemicals = 200ml + 600ml = 800ml

Amount of water  = Total volume of Liquor – Total amount of chemicals = V – T

= 6000ml – 800ml

= 5200ml of water

Therefore, the amount of Water to be used is 5200ml


QUESTION #7

150gm of dyed material was found to have 3gms of dye present and if the material is dyed with 4% shade, Calculate the % Exhaustion?

In 150gms of dyed material –> 3gms of dye is present

The original weight of material = 150 – 3 = 147gm

Now, 4% Shade means, for 100gms of material 4gms of dye is used

Therefore, for 147 gm –> 147*4/100 = 5.88gm of dye should be used

 

By definition of % Exhaustion,

% Exhaustion = (Amt of dye transferred/Amt of dye used)*100

Therefore, % Exhaustion = (3/5.88)*100 = 51.02%

 

Therefore, the % Exhaustion for this dyeing is 51.02%


QUESTION #8

3kg of Cotton material is dyed with 4% Shade keeping MLR 1:40. Calculate the amount of dye in gms and water in litres required for this dyeing.

Weight of the material (W) = 3kg = 3000gms

4% Shade = 4gm of dye used for 100gm of material

therefore, for 3000gms of material –> 3000*4/100 = 120gm of dye is to be used.

Since the MLR is 1:40,

the Total Volume of Liquor (V) = W*MLR = 3000*40 = 120000ml

Therefore the amount of water to be taken = V – T = 120000 – 120 = 119880ml approx.

i.e., 119.88 Litres of water to be used approximately

If MLR is changed from 1:40 to 1:20,

then the total volume (V) = W*MLR = 3000*20 = 60000ml

Therefore the amount of water to be taken = V – T = 60000 – 120 = 59880ml approx.

i.e., 59.88 Litres of water to be used approximately

Since the % Shade so expressed is independent of MLR, therefore the % Shade will remain the same as 4% Shade, But since there is lesser amount of water and almost double concentration of dye in the bath in case of 1:20 MLR as compared to 1:40, the depth of the shade will be unarguably deeper in case of 1:20 MLR. But, literally both the shades will be called as dyed with 4% Shade irrespective of the MLR used.


QUESTION #9

While dyeing 10kg of material, 80% exhaustion occur. If after dyeing, 20gms of dye remains in the bath, Calculate the % Shade of dye.

Let ‘x’ gm of dye to be transferred into the material. Since, 20gms of dye remain after dyeing, then total amount of dye used –> (x + 20)gm

Since, % Exhaustion = 80 as given

80 = {x/(x+20)}*100 …………(by defn, (amt of dye transferred/amt of dye used)*100

80 = 100*x/x+20

80(x+20) = 100x

80x+1600 = 100x

20x = 1600

therefore, x = 80

Therefore the total amount of dye required = x+20 = 80+20 = 100gm

Now for 10kg i.e., 10000gms of material 100gm of dye is used

Therfore, for 100gms of material –> 100*100/10000 = 1gm of dye to be used

Therefore, the % Shade for this dyeing is 1%


 

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