Quiz#: 6 Name Ronak Rare 1. When heat is absorbed by the system and work is done
ID: 553448 • Letter: Q
Question
Quiz#: 6 Name Ronak Rare 1. When heat is absorbed by the system and work is done by the system on the surroundings then (A) (C) (E) q is negative and w is positive. both q and w are negative. q is positive for endothermic processes and w is positive for endothermic processes B) both q and w are positive. q is positive and w is negative. 2. In which one of the following reactions under constant pressure would you expect Bil to be SUBSTANTIALLY greater than (art > AU)? Note 11 = U + Pav (A) H2(g) + Br2(g)_ 2HBrig) (C) Cao(s) + CO (g CaCO(s) (E) HCl(aq) + NaOH(aq)- NaCl(aq) +11:0() 3. From the following data, AH 393.5 kJ/mol H =-285.8 kJ/mol }{--31 19.6 kJ/mol C( graphite) + O2(g)- CO2(g) 2C2Ho(g) +70(g) 4CO-(g)+6H 00) 2C(graphite) +3H:(g) C-Ho(g) calculate at least how much energy is needed to produce 500 g of ethane (C Ho) from the reaction below (hint: find the 11 of the reaction first) 500 /7 moles C2H1 2x2 24 30Explanation / Answer
Finding the Delta H of the reaction: 2C (graphite) + 3 H2 (g) -------> C2H6 (g)
From the given data
For reaction 1 : Delta H1 = -393.5 kJ/mol
For reaction 2 : Delta H2 = -285.8 kJ/mol
For reaction 3: Delta H3 = -3119.6 kJ/mol
We can get the our desired equation if we perform 2 * (reaction.1) + 3 * (reaction.2) - (Reaction.3 / 2)
Now the Delta H our reaction =( 2 * Delta H1 ) +( 3 * Delta H2) - (Delta H3/2)
= (2 *-393.5 kJ/mol) + ( 3*-285.8 kJ/mol) - ( -3119.6 kJ/mol / 2)
= - 787 kJ/mol - 571.6 kJ/mol + 1559.8 kJ/mol
Delta Hrxn = 201.2 kJ/mol
So , to produce 1 mole of C2H6 which is 30 g, we require 201.2 kJ/mol
To produce 500 g of C2H6 which is 16.7 Mole we require 201.2 kJ/mol *16.7 mol = 3360.04 kJ
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