7. A waste material consists of sand (SG 2.7), a chemical salt (SG 2.1) and a de

Question

7. A waste material consists of sand (SG 2.7), a chemical salt (SG 2.1) and a dense plastic (SG 1.4) 200 g of a representative sample from the material is found to have a density of 2300 kg/m. The salt is dissolved out of the sample which, after drying, now weighs 170 g What is the composition of the waste material? 8. You are required to measure the mass and volumetric flow rate of a slurry stream. The slurry contains only water and solids. You take a bucket and stop watch and measure the time taken to fill the bucket. From these measurements, the following information is obtained. The stream fills a 10 litre bucket in 13.5 s. A sample of the slurry weighing 767 g is filtered and dried. The dry solids weigh 148 g The density of the solids only is known to be 3200 kg/m2. Calculate the mass flow rate of the slurry stream. 9. Calculate the density of an empty rubber lined steel pipe with an inside diameter of 0075 m, and an outside diameter of 0.079 m. The rubber lining reduces the pipe inner diameter of the 0.069 m. Assume that the SG of steel is 7.9 and the SG of the rubber is 1.52 pipe to G of the rubber is 1.52 The following basic exercises involve mixtures of chemical species A, B and C which have molecular weights of 45, 16 and 82 respectively

Explanation / Answer

Problem 7

Total weight of sample = 200 g

Density of sample = 2300 Kg/m3 = 2.3 g/ cm3

Volume of sample = Weight/density = 200 / 2.3 = 87 cm3

Assume Mass of sand = X (g)and Mass of Dense plastic = Y(g)

Volume of Sand = X(g)/ 2.7 where density of sand= 2.7 g/ cm3

Volume of Plastic = Y(g)/ 1.4

Apply Mass balance

Sand+ Salt+Plastic = total weight

X+170+Y=200

X+Y=30 (I)

Apply Volume balance

Volum of Sand + Salt + Plastic = Total Volume

X/2.7 + 170/2.1 + Y/1.4 = 87

X/2.7 + Y/ 1.4 = 6 (II)

Solve equation i and ii

We get

X= 44 g .. Y = -14 g  

Its Does mean that It is Pure sand

Sand copmpostion is 100 %

we are only allow to slolve 1 question at time

Thanks

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