Thursday, September 5, 2013

AP Chemistry Question of the Day --19


Welcome back to my blog. Here comes the answer to question 18 I posted yesterday. The correct answer is C

From the reaction we know, K and Cl2 reacts in a 2:1 mole ratio. 2 mole of K (78g) will react with Cl2 (71g), which indicate that the mass consumed for K is greater than Cl2 for a complete reaction. If we have same mass of K and Cl2, then Cl2 will have leftover. Answer D is not correct because if both K and Cl2 are left, the reaction is not complete yet. So, answer C is the right answer. 


Following is Question 19 of the series. It is in continuation of Question 17 and 18. 
19. The elements K and Cl react directly to form the compound KCl according to the equation below.




Which of the values of ΔH for a process in the table is (are) less than zero (i.e., indicate(s) an exothermic process)?



(A) z only
(B) y and z only
(C) x, y, and z only
(D) w, x, y, and z



I will post the answer and explanation tomorrow. 

Thank you very much for reading my post, I am available to discuss any topics in AP chemistry. Please give me a call at 604-808-6827 or email me at vancouverchemistrytutor@gmail.com. My website is located at www.vancouverchemistrytutor.com.

Regards!

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