Finding the strength of caustic soda

 

In Textile Processing the following materials are considered to be basic chemicals or bulk chemicals used in processing. The quality of each product whether basic or auxiliary chemical would certainly affect the final quality of textile processing. So a good dye-house should have a continuous quality monitoring procedure like one shown below. As and when a new product or chemical enters your dye-house, its quality should be compared with the previous supply without fail.

Caustic Soda lye:
Take approximately 25 grams of caustic diluted to 500 ml. From this take 20ml and titrate with 1 N, H2SO4 using phenolphthalein as indicator. Percentage Strength = V x 40 x 100/ 20 x 2 x wt where V is the volume of H2SO4 consumed and wt = 25/500 x 20 grams.
Conversion of Caustic soda concentrations:
To convert a weight of a caustic soda solution to a weight of solid caustic soda, multiply by the %w/w content and divide by 100.
Example: How much sold caustic soda should be used in place of 12 kg of 100TW caustic soda (% w/w = 47.33)?
Calculation: 12 x 47.33/100 = 5.7 kg NaOH solid.
To convert a volume of caustic soda solution in to weight of solid caustic soda, multiply the volume, in liters, by the g/l content of the solution.
Example: How much solid caustic soda should be used in place of 12 liters of 48.1°Be (-710g/l NaOH) caustic solution?
Calculation: 12 x 710 = 8520g = 8.5kg of NaOH solid.
Specific Gravity and concentration of Caustic Soda solutions at 20C

Specific Gravity and concentration of Caustic Soda solutions at 20C
SG Be TW %W/W G/L
1.000 0 0 1.05 10.6
1.050 6.7 10 4.68 48.9
1.100 13.0 20 9.19 101.1
1.150 18.8 30 13.73 157.9
1.160 19.8 32 14.64 169.8
1.170 20.9 34 15.54 181.8
1.180 22.0 36 16.44 194.0
1.190 23.0 38 17.35 206.4
1.200 24.0 40 18.26 219.0
1.210 25.0 42 19.61 231.8
1.220 26.0 44 20.07 244.9
1.230 26.9 46 20.98 258.0
1.240 27.9 48 21.90 271.5
1.250 28.8 50 22.62 285.2
1.260 29.7 52 23.28 299.0
1.270 30.6 54 24.65 312.9
1.280 31.5 56 25.56 327.1
1.290 32.4 58 26.48 341.6
1.300 33.3 60 27.41 256.2
1.310 34.2 62 28.33 371.1
1.320 35.0 64 29.26 386.2
1.330 35.8 66 30.20 401.6
1.340 36.6 68 31.14 417.2
1.360 38.2 72 33.06 449.6
1.370 39.0 74 34.03 456.0
1.380 39.8 76 35.01 483.2
1.390 40.5 78 36.00 500.4
1.400 41.2 80 36.99 518.0
1.410 42.0 82 37.99 535.6
1.420 42.7 84 38.99 553.6
1.430 43.4 86 40.00 572.0
1.440 44.1 88 41.03 590.8
1.450 44.8 90 42.07 610.0
1.460 45.4 92 43.12 629.6
1.470 46.1 94 44.17 646.2
1.480 46.8 96 45.22 669.2
1.490 47.4 98 46.27 698.2
1.500 48.1 100 47.33 710.0
1.510 48.7 102 48.30 730.4
1.520 49.4 104 49.44 751.2
1.530 50.0 106 50.50 772.4