07221. Solving a chemistry problem

1. The specific surface area of a sol consisting of cubic particles with a linear size of 120 nm is (m-1):
a)5*107 b)1*109 c)5*108 d)5*10-9

2. The dispersity of an aerosol consisting of spherical particles is 12.5 µm-1. Their radius (m) is equal to:

a)8*10-8 b)40*10-9 c)40*10-5 d)4*108

3. The osmotic pressure of a solution with a concentration of 70 kmol/m3 at a temperature of 20 C is equal (Pa):

a) 11.6 b) 14.5*103 c) 170.5 d) 1.7*105

4. Two sols have the same mass concentrations but different particle sizes. The ratio of the osmotic pressures of these sols is р2/з1=0.001. The ratio of their radii r2/r1

a)0.1 b)0.001 c)10 d)1000

5. The coagulation threshold of a negatively charged sol for K3[Fe(CN)6] is 20.67 mol/m3, and for NaCl

a) 62 mol/l b) 0.255 mol/m3 c) 0.062 mol/l d) 0.255 mol/l

6. The maximum adsorption is 6*10-12 mol/mm2. The area (m2) occupied by one molecule is equal to:

a) 2.7*10-17 b) 2.8*10-15 c) 2.8*10-19 d) 2.8*10-16

7. The partial concentration of particles (m-3) of a sol with a half coagulation time of 6 minutes and a coagulation constant of 8*10-7 mm3/s is:

a) 2.1*108 b) 3.5*106 c) 3.5*1012 d) 2.1*105
8. Lead iodide sol was obtained by reacting 10 ml of 0.002 M lead nitrate solution and 4 ml of 0.005 M sodium iodide solution. In this case, a sol is obtained, the micelles of which have the structure
9. The ratio of the thicknesses of the diffuse parts of the EDL λ1/λ2 is 0.1. The ratio of ionic strengths of two sols I1/I2 is

a)0.01 b)10 c)0.1 d)100

10. The excess pressure created between two plates, the distance between which is 20 μm, by a liquid with a surface tension of 72 mN/m is ... (Pa)

a)7.2*103 b)1.44*104 c)1.44*107 d)7.2*106