Help with a few SAT 2 Chem Questions

mwahal
Fri, 04 Oct 2013 17:46:36 +0000

Hi All

My son has SAT2 Chem tomorrow, here are few questions he is struggling and want to know answers


When chlorine gas and hydrogen gas reacts to form hydrogen chloride, what will be the change of enthalpy of the reaction ? (bond energies are at the end of the tests)


In the table listed - “Cl-Cl” -> 240 and “H-Cl” -> 430 and “H-H” 435


How much heat is required to the temp of the 85 gms of water from 280K to 342K
What is the voltage of the voltaic cell Zn|Zn^2+||Cu^2+|Cu at 298K if [Zn^2+] = 0.2M and [Cu^2+] = 4.0M


Cu^2+ + 2e^- –> Cu E^o = +0.34V
Zn^2+ + 2e^- –> Zn
E^o = -0.76V
[Note E= E^o - (0.0591/n)(log Q) ]


Substance X has three common isotopes: X-48, X-49 and X-51. If the relative abundances of these three isotopes are 42%, 38% and 20% respecitively, what is the atomic mass of substance X ?
T/F Question


Ai^3+ + 3e^- –> Ai is a correctly balanced oxidation reaction

BECAUSE

Ai^3+ + 3e^- –> Ai correctly demonstrates conservation of mass and conservation of charge.

Thanks you all !

Mwahal

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