Q1. A thick layer of water stands still over a slab of sodium chloride salt. The salt gradually dissolves and diffuses into water, with the concentration of salt at the slab-water interface kept at 380 kg m-3 . The water is initially pure. The diffusivity of salt in water is 1.210-9 m2 s -1 . The density of the salt is 2165 kg m-3 .

(a) Using the information in TABLE Q3, calculate the salt concentration at 10.2 mm from the slab-water interface after 24 hours. (5 marks)

(b) Calculate the thickness of the salt dissolved in 24 hours. (6 marks)

(c) Calculate the flux of diffusion at the slab-water interface at the 24th hour.

x	erf(x)	efrc(x)
0	0.0000	1.0000
0.5	0.5205	0.4795
1.0	0.8427	0.1573
1.5	0.9661	0.0339
2.0	0.9953	0.0047
Infinity	1.0000	0.0000

Can you help me with these questions please using the Table above and assuming a semi-infinite medium.