WK-7_Written_Assignment_CHE-111-Aug_2019.docx - Hello Prof My sincere apologies for the late submission of the assignment and my failure to seek your

WK-7_Written_Assignment_CHE-111-Aug_2019.docx - Hello Prof...

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Hello Prof, My sincere apologies for the late submission of the assignment and my failure to seek your prior approval for late submission. I have been away the whole of last week on business conference and so couldn’t do any school work at all. I am therefore a week behind at this point but making all efforts to catch up to date most likely by end of next week. By this, I would also be submitting this week’s assignment (8) late as well. I am counting on your kind consideration, and please accept my apologies once more. Sincerely, Name: Francis Dake College ID: 0592428 Thomas Edison State University General Chemistry I (CHE-111) Section no.: Week 7 Semester and year: August, 2019 Written Assignment 7: Energy and Thermochemistry Answer all assigned questions and problems, and show all work. 1. Consider this reaction: 2CH 3 OH( l ) + 3O 2 ( g ) 4H 2 O( l ) + 2CO 2 ( g ) H = –1452.8 kJ/mol a. Is this reaction endothermic or exothermic? (2 points) This reaction is exothermic reaction because the law on conservation of energy/heat maintains that the transfer of energy or heat during a reaction ( between a system and surroundings) does not change the total energy of the universe since energy/heat can not be created nor destroyed. Therefore, the sum of energy changes must always be zero. We also know that in an exothermic reaction, the system loses energy/heat to the surroundings and as a result the energy/heat in the product becomes less than was in the system. 1 Copyright © 2017 by Thomas Edison State University. All rights reserved.
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The reaction illustrated above is a combustive reaction where the end products are water and carbon dioxide as shown in the reaction product above. In combustive reactions, there is always burning of substance which releases energy/heat to the surroundings of the system. We also see from the above, that the change in heat (∆ H ) is given as ∆ H = –1452.8 kJ/mol. The negative sign indicates a loss and more so, –1452.8 kJ/mol is less than zero which is an indication of energy/heat being released/loss from the system hence an EXOTHERMIC reaction. b. What is the value of ∆ H if the equation is multiplied throughout by 2? (2 points) Per the rules for thermochemical equations, when equation is multiplied through by a factor, the change in heat/energy must also change by the same factor. Therefore, ∆ H = 2 (–1452.8 kJ/mol) = –2905.6 kJ/mol c. What is the value of ∆ H if the direction of the reaction is reversed so that the products become the reactants and vice versa? (2 points) If the direction of the reaction is reversed so that the products become the reactants and the reactants become the product, the value will be ∆H = +1452.8 kJ/mol That is, magnitude of the value will remain the same but with a positive sign or a gain instead of a loss ( ∆ H = 1452.8 kJ/mol) because the system would need same magnitude of energy/heat to yield the product except that in this case the system would be absorbing the energy from its surrounding thus undergoing an ENDOTHERMIC reaction which always yields a positive change or gain in energy/ heat change.
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