Sieve size 10 mm 5 mm 2.5 mm 1.25 mm 630 µm 315 µm 160 µm Pan
Weight
retained (g)
45
123
169
184
189
133
88
76
Sieve Size Weight
Retained (g)
Cumulative Weight
Retained (g)
Cumulative % Weight
Retained (%)
10.0 mm 45 45 4.5
5.0 mm 123 168 16.7
2.5 mm 169 337 33.5
1.25 mm 184 521 51.7
630 µm 189 710 70.5
315 µm 133 843 83.7
160 µm 88 931 92.5
Total 931
Problem 3 (4 Points)
Total (g)
1007
Note: Do not use the total weight of the
aggregates for the calculation of
the fineness modulus, instead use
the total weight of all the specified
sieves from 10mm to 160µm
Sample Calculations (for 1.25mm sieve)
Cumulative amount retained (g) = 45 + 123 + 169 + 184 = 521
Cumulative Retained (%) = (521/1007) = 51.7%
Fineness Modulus = (4.5 + 16.7 + 33.5 + 51.7 + 70.5 + 83.7 + 92.5) / 100 = 3.53
17.5 A Zn/Zn2+ concentration cell is constructed in which both electrodes are pure zinc. The Zn2+
concentration for one cell half is 1.0 M , for the other, 10-2 M . Is a voltage generated between the two cell halves?
If so, what is its magnitude and which electrode will be oxidized? If no voltage is produced, explain this result.
Solution
This problem calls for us to determine whether or not a voltage is generated in a Zn/Zn2+ concentration
cell, and, if so, its magnitude. Let us label the Zn cell having a 1.0 M Zn2+ solution as cell 1, and the other as cell 2.
Furthermore, assume that oxidation occurs within cell 2, wherein [Zn22 ] = 10-2 M. Hence,
Zn2 + Zn12+ Zn2
2+ + Zn1
and, employing Equation 17.20 leads to
V = 0.0592
2log
Zn22
Zn12
=
0.0592
2log
102 M
1.0 M
= + 0.0592 V
Therefore, a voltage of 0.0592 V is generated when oxidation occurs in the cell having the Zn2+ concentration of
10-2 M.