c. 8.32 x 10+5 19. A certain liquid has a viscosity of 1 x 10 +4 poise and a den
ID: 1074466 • Letter: C
Question
c. 8.32 x 10+5 19. A certain liquid has a viscosity of 1 x 10 +4 poise and a density of 3.2 g/mL. How long will it take for platinum ball with a 2.5 mm radius to fall 1 cm through the liquid? The density of platinum is 21.4 g/cm3 a. 28.4 s 20. A quantity of 2.00 x 10+2 mL of 0.862 M HCl is mixed with 2.00 x 10+2 mL of 0.431 M Ba(OH)2 in a constant pressure calorimeter that has a heat capacity of 453 J/°C. The initial temperature pf the HCl and Ba(OH)2 solutions is the same at 20H8oC. For the process. H+(aq) + OH-(aq) H2O(l), the heat of neutralization is - 56.2 kJ. What is the final temperature of the mixed solution? a. 23.05oC 21. The first step in the industrial recovery of zinc from the zinc d. 9.04 x 10+5 b. 33.4 s c.40.5 s d. 48.9 s b. 25.03°C c. 27.08°C d. 28,09°C ulfide ore is roasting, that is, the conversion of ZnS to ZnO by heating:2ZnS (s)+3 O2(g)--2ZnO(s) +25O2(g) AHr =-879 kJ Calculate the heat evolved (in kJ) per gram of ZnS roasted.Explanation / Answer
20)
Number of moles of HCl = Volume of HCl (in L) * molarity of HCl = 200/1000 * 0.862 = 0.1724 moles
Number of moles of Ba(OH)2 = Volume of Ba(OH)2 (in L) * molarity of Ba(OH)2 = 200/1000 * 0.431 = 0.0862 moles
The reaction happening will be
Ba(OH)2 + 2HCl ----- BaCl2 + 2H2O
Number of moles of H+ and OH- getting neutralied = 0.1724 moles
Heat of neutralization = 0.1724 * (-56.2) = -9.6888 kJ
Total volume of solution = 200 mL + 200 mL = 400 mL
Assuming the density value equal to 1
We can write heat evolved = mass * specific heat capacity * (change in temperature)
9688.8 = 400 * 4.186 * (change in temperature)
change in temperature = 5.7864
Tf - 20.468 = 5.7864
Tf = 26.2664
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