Question

1). The following reaction occurs in basic solution. Identify the oxidizing agent. (Note: The equation is not balanced.) Zn(s) + NO3-(aq) ® Zn(OH)42-(aq) + NH3(aq) OH-(aq) NO3-(aq) H2O(mc010-1.jpg ) Zn(s) NH3(aq) 2). Ethylene glycol is used in automobile radiators as an antifreeze. Use the following information to determine the freezing point of an antifreeze solution made by mixing 2.5 L of ethylene glycol with 2.5 L of water. Ethylene glycol is essentially nonvolatile and it does not dissociate in water. molar mass of ethylene glycol = 62.1 g/mol density of ethylene glycol = 1.11 g/mL density of water = 1.00 g/mL Kf for water = 1.86°C kg/mol –1.6°C –33°C –39°C –24°C –16°C

Answer 1

1. oxidizing agent : which involves in reduction.

answer: NO3-(aq)

2. DTf = i*kf*m

DTf = T0-Tf = 0 - Tf

DTf = i*Kf*m

i = vanthoff factor of ethylene glycol = 1

Kf = frreezing point constant of water = 1.86 K/m

molality(m) = (w/mwt)*(1000/W)

w = amount of ethylene glycol = 2.5*10^3*1.11 = 2775 g

M = molarmass of ethylene glycol = 62 g/mol

W = amount of water = 2.5*10^3 = 2500 g

             = (2775/62)*(1000/2500)

             = 17.9 m

0-x = 1*1.86*17.9

x= freezing point of solution = -33.3 C

answer: -33 c