Chapter 4 Section 8 Chem to Go Questions

  1. Drawings – probably did in class, couldn’t put on blog.  Would depict both endothermic and exothermic energy diagrams.
  2. A – Endothermic because heat is going in and displacing the cold.  This describes ∆H.  B – This is creating more disorder because heat is added and separating the molecules, causing a phase change.  This causes more disorder.  C – ∆H needs to be strongest to for it to be spontaneous because this is the overall heat of the reaction, and what it starts out with.  
  3. A – This is a closed system, with very little surroundings.  B – The bar graph would show the decrease in energy, with an increase in the very end.  C – Exothermic  D – This is non-spontaneous because it required outside forces for it to occur.  E – 0.219 would be where the X is  F – Endothermic  G – Spontaneous because it didn’t require an outside force for it to occur.  H – 78 j/mol  I – Negative because the process is reversed and at room temperature.  
  4. A

Chapter 4 Section 8 Chem Talk

Back at it again with the chem talks.  The amount of these I’ve done is incredible.  I think this is my last one.  As I lay next to the chem talk on its deathbed, I reflect on all of the time we’ve shared together, all those priceless memories.  But I still have to do one more so lets just get it over with.  Systems and their surroundings.  Basically, what it is and what is going on around it.  The “it” in my case is rubber bands, as my extensive work with them in the lab we just did calls for me to consider myself and expert on the subject.  We stretched them, condensed them, even made them recite all the words to Gloria Gaynor’s “I Will Survive.”  We found out that heat can go in and out of them.  We also had to determine what kind of systems they were, open or closed.  In an open system, energy can pass between the system and surroundings.  A closed system is the complete opposite.  We had many different examples of both.  We then examined the law of conservation of energy, which states that energy cannot be created or destroyed.  This calls for changes in entropy, which I intricately discussed in my last chem talk.  We then repeated basically the same exact thing as we did in the last lab, where we predicted if the reaction was spontaneous, and all that jazz, speaking of which is an excellent major motion picture.  Then it talked about Gibbs Free Energy, which is this big complicated thing involving deltas and letters.  There are various combinations in which the reactions are favorable, for example, if ∆G, the reaction cannot be spontaneous.  ∆G represents Gibbs free energy, and if it’s negative, it won’t be spontaneous.  That’s elementary.  We had to do this in the lab, determining whether or not the energy was taken in or given, and if the reaction was spontaneous.  Whole lotta math.  Then I read an interesting section on polymers and monomers.  Polymers are made up of monomers, kind of like how chemistry is made up of devious plans in order to make your education harder.  The stretching of the rubber band determined is entropy; if it was stretched, heat as added because there was less disorder.  When it was contracted, it was the opposite.  Then it talked about other types of polymers, such as thermoplastic polymers.  These are used to stitch the working parts of the mechanical heart to the heart itself.  Complicated.  Don’t want to think about it.  There are so many types of polymers that it hurts me.  Wow that took long.  Until next time, although there isn’t one.

Chapter 4 Section 7 Chem to Go Questions

  1. A – Endothermic  B – Endothermic  C – Exothermic  D – Exothermic
  2. A – 947.66 j/mol  B – Endothermic because there is a phrase charges from liquid to gas  C – If the ratios are off, the reaction cant happen, so ∆H wouldn’t be possible.  D – 897.66  E & F – couldn’t do
  3. A – The reaction going on inside the MRE heater is endothermic because heat is going inside of the bag and not being released unless acted on by an outside source.  B – The reaction doesn’t occur spontaneously because there needed to be an outside gas for it to happen.  C – there is more energy on the reactants side than on the products side.
  4. D

Chapter 4 Section 7 Chem Talk

I’ve been extremely busy lately, so this chem talk is just a use of time that a person like myself would call “unnecessary.”  But no worries, who doesn’t want a nice healthy dose of chemistry in their day?  My doctor told me it could make me feel better.  Here goes it.  This one talked heat changes, both exothermic and endothermic.  Heat going out and going in, as I would tell random infants walking next to me on barren sidewalks.  These are called thermodynamics, and answer the question, “can a reaction occur spontaneously?”  In the lab we just did, we heat up magnesium in test tubes and watch the reactions occur.  In no ways whatsoever was a captivated, or even remotely awestruck, but hey, you gotta do what you gotta do.  So I watched it, and surely the test tubes heated, and a reaction occurred.  Carbon dioxide filled up the tube, and bang; chemicals.  There was no actual bang I just wanted to write that in to make it seem interesting.  We then had to tell if it was endothermic or exothermic.  Endothermic means heat is going in, and exothermic means heat is going out.  Depending on which one it is would determine its change in enthalpy, which is represented by ∆H.  This is the change in energy, to be more specific.  This is represented by an energy diagram, which shows bumps and all kinds of things.  Where the energy ends up is how enthalpy is determined, which is why this is so detrimental to my education.  The bump usually has a vertex, which shows the activation energy, the highest point.  The holy grail, Dr. Jones.  We didn’t have to draw energy diagrams in the lab, but they would look very similar to the ones in the textbook.  Overall this lab was eventful, and by that I mean in no way at all.  But its ok.  I enjoyed it.   

Chapter 4 Section 2 Chem to Go Questions

  1. A isn’t balanced, and you can tell right away by the number of carob atoms in the reactants section.  There needs to be at least 4, and in there are only two.  The mass wasn’t conserved.

2. One mistake that was made was that the least common multiple of each of the atoms wasn’t taken into account, and some of the atoms (Cl) weren’t balanced.

3. Na wasn’t put on the products side

4. KI2 + MnI2 + O4I2

5. a) Na + Cl2 = NaCl2  b) C3H8 + 5O2 = 3CO2 + 4H2O  c) MgCO3 + 2HBr = MgBr2 + CO2 + H2O  d) CaCl2 + 2AgNO3 = Ca(NO3)2 + 2AgCl  e) 2KClO3 = 2KCl + 3O2  f) Fe + 2CuNO3 = 2Cu + Fe(NO3)2

6. a) The amount of oxygen and hydrogen atoms in each compound  b) MgOH2

7. It has to be calcium chloride because of the reaction that it has with oxygen.

8. Iron because of the reaction it has with the elements.  Only iron would allow for the crystal precipitates to form a solution.

9. The 3 in front of the H’s on both sides are coefficients, and the rest are subscripts

10. D

11. D

12. B

Chapter 4 Section 2 Chem Talk

I’ve been loaded with work lately, so to do this just seemed like a waste of time.  But, mom’s been on my case lately so I’ll do it.  As long as I make her happy.  Here’s some chemistry for you.  The of conservation of mass is basically that you have to balance an equation when you need to.  Matter can’t be created or destroyed, but it can change form.  This is why you need to balance your equations.  In the lab we just did, we practiced balancing equations when given different molecules and different forms of matter.  Then I realized I was getting a full-blown history lesson when it went to the scientists who discovered that mass always needs to be conserved.  Democritus, yeah, that was the guys name.  Smart dude.  He helped us all out by teaching us something that makes everything much harder than it has to be.  Some of the stuff we did in the lab was pretty hard.  Molecules with many elements had to be balanced, and my lab partners are I were bamboozled.  You like that word?  Me too.  Well, that’s all for now.  Until next time.  

Chapter 4 Section 1 Chem to Go Questions

1.) a) Endothermic  b) Endothermic   c) Exothermic

2) a) disorder increases   b) disorder increases   c) disorder decreases

3) The reactants are iron, oxygen, and iron oxide.  The products are potassium chlorate, potassium chloride, and oxygen.  This means that the disorder decreases, since the molecules bonded and took a more solid form.

4) C

5) A

6) A

7) Partially filling the balloon with baking soda is the best method because it caused the balloon to fill up faster than all the other methods.  The baking soda quickly reacted to the balloon and it filled up faster than all the other methods.

8) The only instance when you would want to fill the balloon slowly is maybe at the end of a Rube Goldberg machine, so that the finish is  timely.  You can start blowing up the balloon when the machine starts to work. 

 

 

Chapter 4 Section 1 Chem Talk

“Four Score and Seven Years ago..”  Wait a second, wrong assignment.  Whoops.  This is chemistry, my favorite subject in the world.  Lincoln will have to wait on this one.  The lab we did in class was enough, and now we’ve got a chem talk to do.  While I was reading it, sleep was consuming me, but some of the parts of this made me wake up and become intrigued. I learned about energy and entropy, which put me to sleep, mainly because their difference is just was is gaining (energy) and one is releasing (entropy).  Also, entropy is more disorderly.  Basically, when matter undergoes a change, there is often a change in energy.  In the lab that occupied a great unnecessary deal of time in class, the ballots either gained or released energy, based on if they inflated or deflated.  Then it went into a whole spiel on how energy bonds are formed, and about input energy, the whole nine yards.  Then they talked about something I knew: arrangement.  The arrangement of the particles within matter will determine its phase, or more specifically for this section, how much energy it has.  If the particles are closer together, it will be a stronger piece of matter, such as a solid.  The more spread out the particles are, the more likely it will resemble a gas.  During the lab, the CO2 gas that filled up the balloon was spread out, so the particles inside the balloon were very spread out.  Well, if you don’t mind, I’m going to go back to my history homework.  See ya.   

Chapter 3 Section 5 Chem Talk

Just stopped everything that I was doing so that I could read a chem talk.  I figured that I would just read on the same thing I already did a lab on, but just for the sake of knowledge.  I jumped off the diving board and landed in the swimming pool of hydrates and anhydrates.  A hydrate contains water as a part of its crystal structure.  An anhydrate is the solid that is left when the water is removed from a hydrate.  Pretty interesting stuff, right?  In the lab we just did, we were given both a hydrate and an anhydrate in the beginning, and we had to determine which was which.  Based on the definitions I gave in the beginning of this, that’s basically how we determined which one was which.  Then it went into my favorite thing ever: numbers.  I almost threw my book out my window.  Chemists use a unit of measurement called a mole, which is just a humungous number.  6.002 x 10^23.  That big.  I couldn’t wrap my head around it.  But then I remembered my lab, oh, my sweet sweet lab.  We had to measure molar mass, which was basically how many moles make up the thing we were measuring.  For the life of me, I can’t remember.  Then the book decided to back away from our friendship and started naming large, unnecessary numbers, and I got a little lost.  Then I learned that chemists can use percent composition data to calculate a formula for an unknown compound.  They can also give the empirical formula, which is the formula for the smallest possible ratio of the elements.  Then there was the molecular formula, but they didn’t go into that.  A lot of numbers and a lot of math, and I was close to getting lost.  But I had a small amount of fun reading this chem talk.    

Chapter 3 Section 4 Chem Talk

Just surprisingly took time out of my day to read a chem talk.  Going in, I thought it was going to be the most boring read of my life, but as I started reading, it was only moderately boring.  I quickly refreshed my knowledge about the electron sea model, which basically tell us how electrons sit in an atom.  Then I learned that the larger sized electrons in the picture represented cations, which are positively-charged metal ions.  In the lab, it was apparent to us that metals don’t hold on to their valence electrons very well, as they are in constant motion around the cations.  This caused the metal to change shape easily, and be bent into any shape we desired.  This freedom for the electrons to move about is what causes malleability, which can make a metal soft, hard, etc.  Then it went into some other subjects that I needed to touch up on a little bit.  I found out (again) that an alloy is a substance that has the properties of a metal, but isn’t a metal.  Then a little history.  One of the earliest alloys used was bronze.  Then it went into the different types of steel, which I knew I would never be using in my lifetime.  Annealed steel contains fewer carbon atoms between the iron atoms, making it a softer metal.  Hardened steel is hard and brittle.  I could already tell, and if I needed a book to tell me that I don’t think I should be studying chemistry right now.  Back on track.  Tempered steel has the properties of both annealed and hardened steel.  It’s hard, malleable, and is used for tools and building materials.  I experienced all these different types of steel in the lab.  When the metal was exposed to different levels of flame, the different types of steel were shown.  Then the textbook went into pure gold.  No shmelting accidents were recorded in the textbook, which was a bit of a downer.  But I did find out that gold is actually an alloy, and has the properties of different types of steel.  Same thing goes for bronze.  Overall, solid read.