Showing posts with label CHEM 213, UBC 化学家教. Show all posts
Showing posts with label CHEM 213, UBC 化学家教. Show all posts

Thursday, March 15, 2018

AP Chemistry Question of the Day --67

It has been a while since I last posted an AP Chem question. I recently got an email acknowledging me that this blog is helpful. I am glad to hear it and decided to resume it. Here comes question 67.

The equilibrium constants for the following reaction:
N2(g) +O2(g) ⇄2NO(g)

are Kp=1.1e^3 at 2200K and Kp=3.6e^3 at 2500K respectively. Which of the following statement is true:

A. Higher total pressure shifts the equilibrium to the left.
B. The partial pressure of NO(g) is less at 2200K than at 2500K
C. The total pressure at 2200K is the same as at 2500K
D. The reaction is exothermic
E. Kp is less than Kc by (RT)

The correct answer is B.

Since both the reactant side and the product side have 2 moles of gas. The change in pressure or total volume will not shift the equilibrium, which eliminate A.
C sounds right but is actually wrong because as the total mole of the gases and the volume of the gases stay unchanged, the total pressure will increase as a result of the temperature change. The total pressure should be higher at 2500K than at 2200K.
As the temperature increases from 2200K to 2500K, the equilibrium constant increases, indicating the  forward reaction is endothermic.
Since there are equal number moles of gases on both sides, the Kp should be equal to Kc

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Friday, September 2, 2016

Dr. Zhang Chemistry Tutoring 张老师化学家教

Ph. D in Chemistry with years of experience offering chemistry tutoring on AP Chemistry, IB Chemistry, SAT Chemistry, Chemistry 11 and 12, University Level General Chemistry and second year Organic Chemistry including UBC CHEM 111, CHME 113, CHEM 121, CHEM123, CHEM 154, CHEM 203, CHEM 213, CHEM 233, CHEM 205, CHEM 235 and CHEM 245, Langara College CHEM 1114, CHEM 1118, CHEM 1120 and CHEM 1220. I can teach with both English and Mandarin. Please call 604-808-6827. 南开大学化学系博士,UBC化学系博士后,多年经验辅导AP化学,IB化学,SAT化学,十一年级和十二年级化学,大学一年级普通化学和二年级有机化学和物理化学,因材施教,深入浅出,中英文结合,帮你理解要点,抓住重点,取得满意成绩。请电604-808-6827.

Wednesday, April 27, 2016

UBC Chemistry Tutor

Experienced Ph. D. in chemistry offering tutoring service for UBC CHEM111. CHEM113, CHEM121, CHEM123, CHEM233, CHEM 235, CHEM 205, CHEM 203, CHEM 213, CHEM 235 and CHEM 245. Personalized tutoring tailored to individual needs. Guaranteed improvement and success.  
For your tutoring needs, please call Dr. Zhang at 604-808-6827.