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Chem 201: Checklist for Exam One

Chapter One

Knowing the three main states of matter and how to convert to moles from a variety of starting points is the most important concept in Chapter One. Density is mass/volume but the units of density vary – g/mL, g/L, g/cm3 – These are important details to notice.

Significant figures is also covered in Chapter One. You should NOT still be making mistakes with significant figures. ALWAYS check your final answer and ask yourself – what is the correct number of significant figures to report your result. During the reporting of laboratory data – many of you ignored significant figures completely when reporting your results. The laboratory is where the concepts of significant figures are applied! Continue reading →

Chem 201: Laboratory Notebooks Due March 3rd.

I will collect the laboratory notebooks March 3rd. The laboratory – “The Atomic Spectra of Hydrogen” which is mostly a calculation exercise will not be done in the laboratory notebook. It will be done on separate paper. This will give me a few days to review the notebooks.

Chem 201: Special Videotaped Problem Solving Session for Exam Preparation

On Monday February 28th at 2:30 pm I will conduct a small group problem solving session for exam preparation. If you would like to participate please send me an email. I will try to publish the video Monday evening but I can’t promise it will be posted in time to watch it before the exam.

Chem 201: Thermochemistry

Tuesday’s class was all about thermochemistry – understanding the difference between heat (energy) and temperature (a measurement of average kinetic energy). We solved heat problems, heat transfer problems and enthalpy problems. We learned to look up standard enthalpies of formation and learned that standard conditions in thermochemistry use T=25oC and not 0oC (used with gas laws, STP). We learned that standard pressure is 1.00 atm for both of these. We used Hesse’s Laws to solve enthalpy problems.

Several demonstrations were performed in class – we looked at a “hot ice” reusable hot pack and a hand warmer based on the oxidation of iron. Also, to strengthen our understanding of gas laws, we saw a counter intuitive demonstration: applying a cold pack to a sealed flask caused the water to boil. (We will discuss the reasons for this on Thursday but see if you can figure it out.)

We have an exam coming up in a week (Tuesday March 1st). Thursday’s class will be all about practicing problem solving. There will also be a quiz (see previous blog entry for details). There will not be a laboratory this Thursday.

Chem 121: Chemical Change

Another busy Sunday goes by. In this class we focused on chemical change and heat energy. Chapter Four begins by discussing change: chemical change and physical change. Chemical change takes place through the formation of new substances by the making and breaking of chemical bonds between atoms. Physical change includes state changes like melting, evaporating, freezing and mechanical changes like glass breaking into a million pieces.  We went on to define what is meant by energy. We discussed how to classify energy into two types: potential and kinetic. Kinetic energy is the energy of motion and heat, a type of kinetic energy, arises from atomic and molecular motion. Potential energy is stored energy – and energy can be stored in chemical bonds. All forms of stored energy arise from four fundamental forces in our universe; gravity, electromagnetic force, the weak force (radioactivity) and the strong force (nuclear binding energy). Energy released during chemical changes is mostly a consequences of electromagnetic force. Continue reading →

Chem 201: Quiz Key and New Video

I’ve posted the key to the last quiz – quiz three retake. I’ve also uploaded a new video – check the video listings.

I would really like to have some feedback about these videos. Are they helpful? Please send me comments via email.

Chem 201: Next Quiz

The quiz on Thursday will be comprehensively over Chapter Five and Chapter Six. Here are some problems you might have:

1. Ideal gas law problems. PV=nRT

2. Combined gas law problems: P1V1/T1=P2V2/T2

3. Gas density problems

4. Questions about the Kinetic Molecular Theory of Gases.

5. Relative rates of effusion

6. Dalton’s Law of Partial Pressure

To prepare for the quiz it would be useful for you to work through these Virtual Chemistry Experiments.

I have also placed a new, multiple-choice, practice quiz about gases on the website.

Here are some types of problems you might have from chapter six:

1. q = mass X c X ΔT  (note: c= specific heat, S.H.)

2. calorimetry

3. Standard Enthalpies, Hesse’s Law

Using Lab Notebooks

I need to emphasize that the laboratory notebook should be the ONLY document you use in the laboratory. I have seen many students carrying around the textbook, scraps of paper, my handouts, printed laboratory instructions – but if you are properly prepared for lab you do not need any of these things – you only need your notebook.

When you collect data I have seen many students write this data on some piece of paper with the intend to place it in the notebook later. This is incorrect laboratory procedure. All data should be recorded DIRECTLY into the laboratory notebook.

I have even seen some folks using pencil. All records should be in permanent ink.

Yes the notebook may become messy. Yes you may record errors and then need to make corrections. But this technique ensures that the data in the notebook is original and not a copy.

Please come to laboratory prepared. Please USE your laboratory notebook correctly. Part of your evaluation in the laboratory is my observations of how you use your laboratory notebook.

Chem 201: Second chance on Quiz Three: Gas Stoichiometry

A few of you have expressed frustration in the following ways:

“I studied for hours but I could not do the problems.”

“These problems don’t look like the ones I practiced.”

“I am concerned about my grade.”

So let’s do it again. If you want to take quiz three again that is fine with me. You need to be able to do stoichiometry problems. You need to be able to work through multiple conversions. I can help you do this but it takes practice. All of these problems have a common pattern – they use the stoichiometry map – they have a chemical equation at their core – they involve lots of conversions. This is what Chemistry 201 is all about! Please remember that the prerequisite for this course is C or better in Basic Chemistry. If you have weaknesses in Basic Chemistry we are going to have to address them.

I will give a retake of this quiz directly after laboratory tomorrow. I suspect the lab will not run late tomorrow so this should not be a problem for most of you. If it is – email me and I’ll make arrangements for you. In the meantime – practice. I’ll be giving a session today at 2:30. I am here until 5PM. Come see me.

You need to be able to solve problems you have never seen before because you understand the concepts. This will happen!! Don’t give up.

Chem 201: Quiz Key and Help with Molarity

Today’s quiz solutions are posted. Please don’t feel discouraged if you are finding the quizzes difficult. This is an important time for you to practice. Some quizzes will be easier than others. Give yourself some time and be patient. No one ever says chemistry is easy.

Have you ever wondered why we talk about classification of matter? In order to know how to determine the correct number of moles of a substance you need to understand how mole concentration is expressed. For a pure liquid the transition from volume to mass and from mass to volume uses density but for a solution the transition from volume to moles uses Molarity.

I found a video that shows a very careful solution to a molarity problem on YouTube. Check it out. The best part is when the presenter sneezes near the end of the video:-)

You could make up some problems for yourself and test if you have the correct solutions using this molarity calculator.

Chem 121: Laboratory Preparation

It is very, very important to come to class prepared. I saw a few instances of very poor preparation and some instances of average preparation and far too few instances of excellent preparation so here are some tips to follow:

  1. Print the laboratory! Coming to class without the laboratory printed does not make a very good impression.
  2. Read the laboratory.
  3. Takes notes on the laboratory in your laboratory notebook. Look up any terminology that you do not understand. Your laboratory book should never be blank when I stamp it.

That’s it! Those three steps will make a big difference in how the laboratory goes for you.

During lab there is ONE VERY IMPORTANT RULE: write directly in your laboratory book. Do not recopy! And write in ink!

Next week we have two laboratories to do – Observing Chemical and Physical Changes and Food Energy. I will post “Food Energy” very soon so check back for it. The lecture will be on Chapter Four.

Spend some time watching videos from The Periodic Table of Videos. You will learn a lot and have fun too. This is a great way to get to know the elements.

Mixture of salt and sand

Mixture of salt and sand

I hope you had fun today and learned something too! We saw examples of mixtures: water and carbon dioxide, chocolate, water and air, sand and salt, and we learned a little bit about physical properties – miscibility, viscosity, crystal form, luster, solubility (a chemical property). Hopefully you also made some careful observations. It is amazing what you begin to see once you pay attention to detail.

The quiz next week will be on any material that is in Chapter Three. You will need to read it! The quiz may have questions on it that I did not cover. Review the two powerpoints I showed in class today. Go over them more slowly. Email me if you have any questions.

See you next week.

Make: Science Room – Making crystal iodine

Chem 201: Quiz on Tuesday

For the quiz on Tuesday please concentrate on PV=nRT problems and problems of gas stoichiometry! For the lecture we will continue Chapter Five.

What is gas stoichiometry?? It is focusing on quantitative relationships of reactions involving gases (like the ones you just did in lab).

Chem 201: Amazing Effort and Success!

Because we lost time due to the snow day we had the difficult task of completing two labs in one day – students worked very hard and stayed on task extremely well. There is no denying the fact that the second lab was rushed but hopefullly with data in hand you all will be able to think through this lab more carefully and make sense of your data. To help you do this I’m going to talk through this lab and point out a few areas of difficulty I observed. Continue reading →

Chem 201: New! Problem Solving Session on Video

With a very sincere thank you to Paul and to Shelly for their participation!
Visit: http://justonly.com/chemistry/videos/ps_video_01/index.php

We had so much fun we’ll do this again next week. You’re all invited.

The videos will be permanently indexed at http://justonly.com/chemistry/videos/index.php

The Disappearing Spoon is Available in Our Library

A couple of copies of “The Disappearing Spoon” are on reserve in our library. You will need to present the call number: QD466. K37 2010 to be able to check out the book. It must be read in the library.

Chem 201: More schedule changes and a study session

Today we could not do the lab because another class was using the lab room – so we will do two labs on Thursday. This means NO QUIZ on Thursday. It will be given next Tuesday instead. Check for an updated syllabus later tonight.

Tomorrow, Wednesday, at 2:30 PM I will hold an extra problem solving session. We will video tape it. I will solve and explain problems for an hour. Bring problems for me to do. Come to my office (inside the Phy. Sci. and Engineering department office – room 3826) and we will have lots of fun!

Those who can’t make it will be able to watch it later on the Internet.

Chem 121: Day Two

Sundays go by in a flash – and this time we found ourselves rushing to finish the laboratories. Some folks were very well prepared – their labs were printed, they had their notebooks and had even taken notes on the lab!! That’s the way to succeed.

density formulaWe covered a lot of territory and you will need to practice what was introduced – so IN ADDITION to doing homework from the textbook – you should work through all of the drill sheets that pertain to the material we covered. We covered adding and subtracting, multiplying and dividing numbers while presenting the results with the correct number of significant figures. We covered the metric system – kilo, milli, ( we mentioned micro and nano but I won’t test on these). We worked through some conversions. We talked about density and I did a few density problems. Practice solving for mass, volume and density given two of these three quantities. We spent the afternoon working through laboratories. We didn’t finish the density laboratory so we will continue that next Sunday.

One VERY IMPORTANT assignment is to design a business card presenting an element of the periodic table. Please make 30 copies of your card. Every student will receive every card so when we finish this activity you will have a nice set of flash cards you can use to learn the names and symbols of the elements. I provide a template that you may use (but you don’t have to use) as a pdf and as a doc file.

Next Sunday is all about the elements. Please read Chapter Three. See you then.

Chem 121: Are you prepared for tomorrow?

Checklist:

  1. You have a laboratory notebook.
  2. You’ve printed out copies of the two labs we will be doing tomorrow.
  3. You’ve learned the vocabulary related to the scientific method and to phases and classification of matter in Chapter One.
  4. You know how to count significant figures.
  5. You know how to put a number into scientific notation.
  6. You’ve read over Chapter Two.
  7. You are planning to bring your calculator to class tomorrow.

See you soon.

Chem 201: Quiz Two Key

You may download the key to the second quiz in pdf format.


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