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What is Kc?

What is Kc?


School: Texas A&M University
Department: Chemistry
Course: Fundamentals of Chemistry II
Professor: Vickie williamson
Term: Spring 2018
Tags: General Chemistry
Cost: 50
Name: chem 102 study guide 2
Description: Test 2 Study guide, Dr. Collins
Uploaded: 03/18/2018
6 Pages 7 Views 7 Unlocks

CHEM 102: Study Guide

What is Kc?

Chapters: 18, 12, 16.7-8

Sorry it’s late y’all. Also, I’m never making them multiple choice again unless y’all  want me to lose any semblance of sanity while making these. Good Luck and email me if you want or need help or something is wrong with the study guide. Chemical Equilibrium (Chapter 12)

1. Kc= [Concentration of products to the power of the  

coefficient]/[Concentration of reactants to the power of the coefficient] 2. Kp = Kc(RT)Δn 

3. Kp= the rate constant for the pressure of each reaction,

4. ∆n=moles of gaseous products – moles of gaseous reactants 5. When a Solid or Pure Liquid are in the reaction, do not include them in the  expression for the equilibrium constant.

6. Reaction Quotients

1. Qc= substituting the initial concentrations of reactants  

and products into the Kc expression

2. Qc<Kc, system proceeds left to right 

What is Kp?


4. Qc>Kc, to the left, to the left, to the left 

7. Rice Tables

1. In a vertical line, write RICE or ICE  

2. Write the BALANCED EQUATION, next to the R,  

(reaction, this step is optional, but you can’t forget to  

balance the reaction), if you didn’t write R, just write it  

above where you want everything

3. Next to the I, underneath each element or compound,  

write the INITIAL concentration, 

4. Next to the C, (change), write the change of each  

compound in terms of x multiplied by the coefficient and  

the direction of the reaction. 

a. If the reaction is proceeding from LEFT TO RIGHT,  

then the REACTANTS ARE NEGATIVE, and the  


b. If the reaction is proceeding from RIGHT TO LEFT,  

then the REACTANTS ARE POSITIVE, and the  


What is Qc?

5. Next to the E, (equilibrium), write the initial  We also discuss several other topics like bus 2110 class notes

concentration combined with the change, I+( ± C) 

6. Given Kc, (or calculated), solve for x through foiling out  

and simplifying. QUADRATIC FORMULA IS BACK. Y’all mfs  

remember this, X=(-b±√(b2-4ac))/2a 

7. USE THE X FROM STEP 6, plug back into the E step and  

there ya go, equilibrium concentrations,  

8. Le Chateliers Principle Don't forget about the age old question of damien salamone

a. Moves away from stress.

i. Some Examples and Rules 

1. If some reactant is ADDED: Moves to products 

2. If some reactant is REMOVED: Moves to reactants 

3. If some product is ADDED: Moves to reactants 

4. If some product is REMOVED: Moves to products 

ii. Changes in Volume and Pressure: can only affect gaseous  species 

1. If the PRESSURE is INCREASED: Moves to side with  

fewest moles 

2. If the PRESSURE is DECREASED: Moves to side with most  moles Don't forget about the age old question of gluconeogenesis bypass steps

3. If the VOLUME is INCREASED: Moves to side with most  


4. If the VOLUME is DECREASED: Moves to side with fewest  moles 

iii. Change in Temperature 

1. Increase in Temperature 

a. Exothermic rxn. = K decreases 

b. Endothermic rxn. = K increases 

2. Decrease in Temperature 

a. Exothermic rxn. = K increases 

b. Endothermic rxn. = K decreases 

iv. Adding a catalyst DOES NOT EFFECT EQUILIBRIUM OR K b.

Practice Problems

1. In a closed, one-liter reaction chamber, nitrosyl bromide (NOBr) decays into  nitrogen monoxide and bromine. The K-value of the reaction is determined

to be 0.42. After 0.9 moles of NOBr is added, calculate the equilibrium  concentration of bromine.

2. In an 8.5 L chamber, carbon dioxide gas is reacted with hydrogen gas to  create carbon monoxide and water. With a K-value of 0.802, calculate the  equilibrium concentration of carbon monoxide if 34 moles of both carbon  dioxide and hydrogen gas is added. We also discuss several other topics like cedarville moodle

3. In a reaction between hydrogen gas and iodine gas, the equilibrium  concentration of hydrogen iodide is determined to be 0.63 M. determine  the K value of the reaction if the initial molarity of hydrogen gas is 0.7 M  and the initial molarity of iodine gas is 0.4 M.

4. In a closed chamber, the reaction ����2(����) + ������2(����) ⇌ ����������(����) + ��������(����) goes to equilibrium. After it goes to equilibrium, some BrOCl is  added. What way will the equilibrium shift?

5. A sealed 5 L reaction chamber has 20 moles of carbon monoxide, 8 moles  of nitrogen monoxide, and 30 moles of carbon dioxide. As the K value is  8.11, determine the concentration of nitrogen dioxide at equilibrium.  

6. Iron (III) oxide and hydrogen react to form iron and water. In a 6.2 L  reaction vessel, 3.35 grams of iron (III) oxide, 4.07 grams of hydrogen gas,  5.75 grams of iron metal, and 3.95 grams of gaseous water are found at  equilibrium. Calculate the equilibrium constant for the reaction.  Don't forget about the age old question of bus 2110 study guide

7. ����3����2����2(����) + ������(����) → ����−(����) + ����3����2����3+(����) The  equilibrium constant for this reaction at 298 degrees Kelvin is calculated to  be 8.22. If 0.4 M of ����3����2����2and 0.7 M of HCl are in the chamber  initially, calculate the concentration of dissociated chlorine at equilibrium.

8. Calculate the Kp of ����4����(2) ⇌ ��2��(��) + ����3(��) given the Kc is 0.77 at  31 degrees Celsius.  

9. For the reaction ��2(��) + 3��2(��) ⇌ 2����3(��), write the pressure  equilibrium constant expression.

Nuclear Chemistry (Chapter 18)

Important Notes

1. Types of radioactive particles 

a. Alpha particles (α): a helium nuclei, 

b. Beta particles (β): electrons, positive or negatively charged c. Gamma rays (γ): Particles unaffected by magnetic fields, aka high  energy photons, leaves in a ray.  

d. Positron (β+), a positively charged electron 

e. Neutrino(v) 

f. Antineutrino(��) 

2. Positron-Electron Collision: When a positron collides with an electron, 2  gamma-ray photons are created, traveling in two directions. This is because  positrons are antimatter which when colliding with normal matter cancels  out. This releases a ton of energy We also discuss several other topics like chm 1025 final exam with answers

3. Electron Capture: The nucleus captures an electron, converting a proton to  a neutron, (reverse of beta decay) 

4. Positron Emission: A proton decays into a neutron, positron, and a  neutrino. 

5. Alpha Decay: An alpha particle is ejected from the nucleus. 6. Beta Decay: A beta particle and an antineutrino are emitted from the  nucleus. 

7. All radioactive decay follows first order kinetics 

Practice Problems 

1. The half-life of carbon-14 to nitrogen-14 is 5730 years (5.73 x 103years). A  nuclear chemical analysis reveals that there is 0.623 mmol of nitrogen-14  for every 1.000 mmol of carbon-14 in a sample. Calculate the age of the  rock to two sig figs.

2. The activity due to the radioactive decay of carbon-14 from a wooden  artifact is measured to be 43. Bq. The activity from a piece of fresh wood of  a similar size is 59 Bq. Given the half-life of carbon-14 being 5.73 x 103 years, calculate the age of the artifact to two significant figures.  

Gibbs, Spontaneity, and Entropy (Chapter 16.7-8)

1. ∆G=-RT(lnK) 

Practice Problems

1. Given the reaction, ��2(��) + 3��2(��) ⇌ 2����3(��), calculate the equilibrium  constant at 25 degrees Celsius. [∆G values; NH3=-16.4 kJ/mol]

2. Given an equilibrium constant of a reaction equaling 2.37, calculate the ∆G  of a reaction at 212 degrees Celsius.


Chapter 12

1. 0.25 M

2. 1.89 M

3. Kc=12.13

4. Reactants, Left

5. 1.39 M

6. Kc=0.831

7. 0.35 M

8. Kp=4.92 x 106 

9. Kp=[����3]2 


Chapter 18

1. 4.0 x 103years

2. 6.0 x 103years

Chapter 16.7-8

1. K= 1.79 x 10-6 

2. ∆G=3.48 x 103kJ/mol

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