5/15 Ice cream site...http://www.wwnorton.com/college/chemistry/gilbert2/chemtours.asp#20
Chapter 10: Boiling and Freezing Points
5/13 We are making ice cream on Wednesday. If you want to bring in more toppings, please do so! If you need to make up a daily quiz, be ready for it on Wednesday. Remember, you don't have to do this, but you have the possibility of replacing your lowest score
5/9 Study for test.Daily Quiz answers. Don't want you to be bored (worked out - sorry if the problems don't line up exactly). Ice Cream = Wednesday. Lab books = Monday. Mystery Acid = Formic acid, 0.08M...hints coming soon if you're nice :)
5/7 Work on Labs! Labs and Test are on Monday
5/3 Be ready for Let's Make a Buffer on Tuesday. Test = 5/13. You might be asking yourself, "Self, do we have a daily quiz on Tuesday?"...yes...duh :) Extra Credit
Let’s make a Buffer
Create a buffered solution using 100. mL of 0.10 M acetic acid and sodium acetate. Make the solution so it has a pH of 5.00. Ms. Michael will test each of these solutions using HCl or NaOH, and if the pH changes more than 1.0 unit, you will lose points.
Some things to think about and answer before next class…
- How much sodium acetate do you need?
- What is a buffer? (use your book to help you)
- If HCl is added to this solution, what will it react with?
- If NaOH is added to this solution, what will it react with?
- If HCl and NaOH are added, why shouldn’t the pH drastically changed?
5/1 I will collect Some Practice Problems at the end of class on Friday. Please bring in a question or 2....not 12! Be ready to discuss both labs (Mystery Acid Lab from today), extra credit, final, and be ready to take a daily quiz.
4/25 Work on titration yippee . Some relatively challenging problems due Monday. There will be a quiz on Monday. Also, tomorrow will be a work day for the most part, so please attempt Yippee, but it does not have to be perfect.
Yippee answers (thanks Emilee):
1: 0.097, 0.57, 7, 11.9
2: 2.41, 0.022L, 4.76, 0.043L, 9.21, 12.04
3: 11.64, 27.5mL, 9.24, 55mL, 4.76, 2.03
4/24 Finish up #2. Here are some helpful hints for Some Relatively Challenging Problems.
4/19 Here are the answers to the understanding check. Please complete Some Relatively Challenging Problems (not number 2 for next class) Answers: 12.8, 9.0, 3.1, 0.25%. If you were not in class, you are still expected to take the quiz on Wednesday.
4/17 Some acid base problems Please be ready for a quiz over anything we learned in class (naming, strong vs. weak, Ka or Kb).
Here are the answers. If you have an issue, please come see me BEFORE class on Friday.
1. a) A,B,CA,CB b) B,A,CA,CB c) A,B,CB,CA
2. a) not really a conjugate BUT would be ClO4- b) HS- c) PH3 d) CO3-2
4. 0.156 M
5. [ClO-] = [HClO] = 4.6x10-5 and [HClO] = 0.075 M ( I used Ka= 2.88x10-8)
6. Ka = 1.8x10-4 and it is 4.2% ionized
7. [ OH-] = 1.6x10-3 M
8. [OH-] = 5.5x10-4 M
9. Ka = 6.05x10-10
4/15 Please complete the pH practice for homework. Need help with logs and pH? Check this out. Please be ready for a quiz over pH next class. Also, your equilibrium retake is 4/22 during ac lab or after school
4/9 Study for your test. Here is the optional assignment....
Optional Assignment (for points!)
Rate Laws p. 433 #33
p. 437 # 71
Equilibrium p. 466 #61, 65
Ksp p. 545 #21
p. 546 # 51
***Show all work. Do them in this order. Due Thursday! No exceptions!
4/3 Finish the Equilibrium Problems because I will collect them on Friday. Be ready for Ksp lab Day 2!
3/12 Please complete p.463 #19-23 odd for class on Monday. Have a safe and happy spring break!!!
3/7 Your Take Home Test is due BEFORE Spring Break - no later than 3/14. YOU MAY NOT TALK TO OTHER PEOPLE, BUT YOU CAN USE YOUR NOTES, BOOK, ETC.
3/5 Work on Kinetics Packet for Monday. Be ready for the test and lab book due date on Thursday.
3/1 Start getting ready for the test. On Thursday, I will be collecting Physical Heat Problems, Gibb's, and lab books. The results for the Flame lab are in.... They aren't great, but we're going with it! For the big nut, 674oC, and the small one, 531oC
2/27 Today we discussed Entropy, Enthalpy and Spontaneity again. Please work on the Gibb's Hw for next time.
I’m pretty sure these are right. If you don’t get the same answer, check the online resource. If you still don’t, shoot me an email because I might have made a whoopsie.
7. -513.5 kJ exo, -17.1 J/K decrease , -508 kJ spon
8. -179.1 kJ exo, -0.1093 kJ/K decrease, -146.9 kJ spon
9. +205.9 kJ endo, +0.2148 KJ/K increase, +144 kJ non spon
10. +176.2 kJ endo, +0.2851 kJ/K increase, +92.1 kJ non spon
11. LR= NaOH, -242.8 kJ exo
c) Start with moles and convert to kJ = -182.1 kJ
d) low T = spon
e) Zn(OH)2 + 2HCl à ZnCl2 + 2HOH Use PV=nRT and the volume is 26.7 L HCl
12. LR = HCl Use PV = nRT and use n for hydrogen gas. The volume is 335 L
b) -854.6 kJ exo, -0.567 kJ/K, -686 kJ spon
c) Convert moles HCl to kJ. Then use that value and call it Q. Solve for delta T (it’s big)
13. Q of the metal = Q of the water. Temperature final is 12.7 deg C
14. Q’s are equal again. 2.3 times more Al than Cu or 0.43 times more Cu than Al
15. a) always spon
b) high T = non spon
c) always spon
2/25 Please complete the Substantive Exercise for homework. Your test and lab book due date is next Thursday.
2/19 Please complete p. 197 #35, 43,45. Get ready for the lab!!!
Have a Hint: The balanced equation for the Target would be better if it was Mg + 1/2 O2 --> MgO (This will be important for later equations, so please change how you balanced that mystery 3rd reaction)
Another Hint: When thinking about your limiting reactants for each reaction, I would try to make the number of moles of each of the LRs the same as each other. This should help your data turn out a little easier to interpret :)
One more Hint: The magnesium strip is 1.4818 g/m
Hess’s Law Lab
Purpose: Determine the Heat of Reaction for this target eqn ------- Mg (s) + O2 (g) ® MgO (s)
**The most straight forward method of determining this value would be to weigh a piece of magnesium, place it in a bomb calorimeter with excess oxygen and initiate the reaction with a spark. We have to be a little more creative J\
Materials/ Equipment: 200. mL of 2.00 M HCl, 10. cm Magnesium ribbon, 1.00 g Magnesium oxide, Styrofoam cups, Logger Pro temperature probe, scoopula, balance, stirring rod, graduated cylinder, etc.?
Procedure: Using the above materials per group, decide what reactions you could perform and what measurements you will want to make to solve the problem.
Hint: 3 equations are required for determining the enthalpy change for the target reaction.
· One will be from the addition of the Mg to an amount of HCl as determined by your group.
· Another will be the addition of magnesium oxide to HCl as determined by your group.
· And the last equation will have to be calculated using standard enthalpies of formation.
To determine the last equation, write the first 2 equations as dictated by Hess’s Law and determine the missing equation that would “complete your puzzle”.
Feel free to use all of your materials, but use them wisely. Come up with a plan BEFORE starting the lab. Assume the specific heat of the hydrochloric acid solution is the same as pure water.
Data and Calculations: Make a data table(s). The accepted ΔH is -602.0 kJ/ mole MgO. Calculate a percent error.
Conclusion: Restate the purpose. Discuss the procedure. Discussion of Theory: use the terms exothermic and endothermic, explain how Hess’s Law is useful, and discuss what the results were. Discuss 2 possible procedural errors and the effect each error would have on the results (the enthalpy of reaction).
2/13 Specific Heat Lab is due Tuesday. Today we did the Really Hot Lab (When you get the average temperature of the flame AFTER computing each trial, let me know, so I can find a class average). Please complete Physical Heat Concepts for Tuesday : 443 J/g, 5.04 snickers, 230.g ice
2/7 Please complete the tutorial on Heating Curves and Phase Diagrams. The retake is Tuesday After School or Ac Lab - second score, no more than a 90% total
2/1 Lab books are due Tuesday. Study for your Test!!! A Few Relatively Challenging Problems is also due Tuesday.
1/30 Please keep working on your optional problems because the test and lab books are Tuesday. Here is another set....Also, A few relatively challenging problems is due Tuesday. Let me know if there are issues with these answers...
1. 2HCl + Ca(OH)2 ® CaCl2 + 2H(OH)
24.6 g HCl, 12.2 g H2O
2. 2Li(OH) + CO2 ® Li2CO3 + H2O
63.37 L CO2, 50.96 g H2O
3. 2NaNO3 ® 2Na + 3N2
178.3 L N2, 122.0 g Na
4. NaHCO3 + HCl ® NaCl + H2O + CO2
LR = HCl, 20 L CO2
5. Ba(NO3)2 + Na2SO4 ® BaSO4 + 2NaNO3
LR = Ba(NO3)2, 60 g BaSO4
6. 2C4H10 + 13O2 ® 8CO2 + 10H2O
LR = O2, 34 L CO2
7. 2HCl + Zn ® ZnCl2 + H2
a) LR = HCl, 98 g Zn
b) 1.5 mol ZnCl2
c) 34 L H2
8. n = 7.67x10^-4 and the answer is 0.0522 g oxygen
9. Na2O + CO2 ® Na2CO3
10. Zn +2HNO3 ® H2 + Zn(NO3)2
11. Metal carbonate breaks into metal oxide + carbon dioxide
0.133 g aluminum carbonate
12. Sodium sulfite + phosphoric acid à sodium phosphate + H2SO3 (this decomposes into sulfur dioxide and water)
LR= sodium sulfite
a) 0.1 mol phosphoric acid
b) See above
c) 0.7933 mol sulfur dioxide
d) 18.9 L
13. 0.0693 g Zn
14. Oops, don't do this one!
15. 1900 mmHg
16. 3.2 L
17. 0.56 L
18. 0.6 L
19. 300 K
1. Octane = C8H18
a) Lr = octane
b) 15.7 L
c) 14.2 g
d) 35.1 g
e) 101 g
2. 614 mmHg
3. Molar mass is 42.1 g/mol -----> C3H6
4. 290. mL
5. 141 L
6. 5.76 mL
7. 0.901 g
8. 29.1 L
9. 4.20 L
10. 2.04 g
11. 1370 mL
12. Carbon dioxide is 1.21 times faster than sulfur dioxide
1/28 Please be ready for a quiz over gases on Wednesday. More gas problems is also due Wednesday. Here is the sheet for presentations...also Wednesday - O boy!
1/24 Today we did the PV=nRT lab. Please work on A Few Relatively Challenging Problems (answers below) Here's a new fun fact... ammonium hydroxide naturally breaks down into ammonia (NH3), which is a gas, and water...
1. 3Na2CO3 + 2H3PO4 ® 2Na3PO4 + 3H2O + 3CO2
a) LR = sodium carbonate
b) 1.132 mol CO2
c) 27.8 L
2. Zn +2HCl ® ZnCl2 + H2
a) Assume P2 and T2 are standards, mass = 0.0677 g Zn
b) Same as above
3. 3(NH4)2SO4 + 2Al(OH)3 ® 6NH3 + 6H2O + Al2(SO4)3
a) LR = ammonium sulfate
Find the volume of ammonia = 17.5 L
4. 2.5 L O2
5. 0.125g aluminum carbonate
7. 108 kPa (100 with SF)
8. 495 K ( 500 with SF)
9. 99 L
1/17 We took notes on the variables, P,V,n,T, and discussed the relationships they have with each other. If you were gone, please get notes from a friend, try the problems, and then come ask questions - thanks. Your homework is called Gas Problems (answers are on this document too---Mina says disregard sig figs...thanks for noticing :) )
1/15 Hey, Great Job on the Murder Investigation! Most people are getting impressive results! Well done :)
Read p. 136-140. Do p.138 Concept Check 5.1 and p.166 #19. LAB BOOKS ARE DUE THURSDAY!!!!!
1/11 Murder Investigation. Heads up: Fun with Moles is due Tuesday (for accuracy) and Labs are due Thursday
1/9 Today we did the Salt Lab. Stoich quiz on Friday and lab books will probably be due next Thursday. Fun with Moles is due Tuesday.
Some more Limiting Reactant Practice for Tiffany and Mina :)
Here is some more stuff....
******LR= sodium hydroxide. There will be 10.2 g sodium nitrate and 3.12g aluminum hydroxide. 8.52g aluminum nitrate reacted, so 1.5g is leftover.
10.00 grams of aluminum nitrate are reacted with 30.0 mL of 4.00 M sodium hydroxide. Calculate the mass of each product formed, as well as the mass of excess reactant (either aluminum nitrate or sodium hydroxide) which remains after the reaction is complete.
1/7 Please work on Fun with Moles because there will be a quiz on Friday. Brush up on those reactions, stoichiometry, molarity, etc. :)
1/3 Work on Limiting Reactant Lab.