Blog 9.1 Heat of Solution (delta H), Using Table I. Due Date April 5th (Thurs)

Post-Lab Questions: (Blog Questions)

1.)   Was your solution process endothermic or exothermic?  Describe the process using terms such as: direction of heat flow, system, and surroundings of the system.

 

2.)   What are the possible sources of error that cause a difference in the value that you got, and the value that was published on the reference tables (table I)? (Human or calculation error are not acceptable.)

 

3.)   How would your numbers for q, moles of solute, and ultimately ∆H (q/mole), be affected if…

a.)   The room temperature was 10^oC colder.  Explain.

 

b.)   You added less chemical, but knew the mass you added.  Explain.

 

c.)   You added 40 mL of water but thought you had added 50 mL.  Explain.

 Enrichment:  (1 pt)

In Florida, when the weather report is calling for freezing temperatures, orange farmers will mist the fruit trees with water overnight in order to prevent damage to the tree and fruit.  The water being sprayed on the tree freezes, but as it does so, this protects the tree from damage.  Explain why this works.

Blog 8.1 Hydrocarbon properties and uses (Due Thursday March 15th)

Hydrocarbons (alkanes, alkenes and alkynes) are very important substances that we use for many things. We drill for and pump crude oil which is a mixture of lots of different hydrocarbons. You need to answer these questions about hydrocarbons, you will have to do some research to be able to answer these questions. Please ignore the temptation to copy and paste your findings into your blog.

First answer these questions:

What is crude oil? What components are in the mixture of crude?

How to we separate the components of the mixture? What physical properties do we use to do that separation?

How do the properties of hydrocarbons change based on their size? How does this influence the boiling point of something small like methane compared to something large with 30 C's or more?

Research one or more of the following of interest to you.  Write 2-3 paragraphs summarizing your findings.

a.     The discovery of oil in the US and the location of the first drilling for oil ever done.

b.     How oil is drilled out of the ground.

c.      The extraction of oil from “oil shale” and “oil sand” deposits.

d.     The refining process used to extract particular components out of “crude oil.”

e.      The likelihood of finding natural gas, oil or coal deposits in Western NY.

f.       Why oil prices have been rising lately, and how the global oil trade is run.

Lab 7.3 Reactivity of Metals

1.  Answer the lab question on the first page of this lab.  CITE EVIDENCE FROM YOUR OBSERVATIONS! Make sure you explain thoroughly.

2.   Why do elements in the same column on the Periodic Table tend to have VERY SIMILAR properties?  Explain in terms of electron configuration! Use specific examples from your groupings.

3.   Describe what happens when an atom of sodium atom interacts with an atom of a nonmetal.  In your description, indicate:

a.   Whether the sodium atom loses or gains electrons,

b.   Whether the sodium atom becomes a positive or negative ion,

c.   The electrical charge of the sodium ion,

d.   Which noble gas sodium’s electron configuration becomes like,

e.   Whether the sodium atom becomes more or less stable as a result of reacting.

ENRICHMENT: 

The elements Li, Na and K are too reactive to be found in nature as pure elements.  Research how chemists obtain pure sodium in the form like we used in lab.

Lab 7.2 Periodic Trends Activity

These three trends are more challenging to explain, explain them:

·        Atomic radii trend going from left to right across a period.  The heaviest elements in a period have the smallest radii. WHY?

              ·        Electronegativity decreases when you move down a group. The larger the atom in the same group, the less it attracts electrons. WHY?

·        Ionization energies as you go from left to right across a period.  It kind of makes sense that it is harder to strip an electron from a metal than from a non-metal, but WHY is this so?

The key to explaining these trends is to figure out what “nuclear charge” is, and then to figure out what it has to do with these property trends.  Google will be a big help if you ask the right question in the search bar!  Good luck, and of course, talk with your teacher as needed!



Why do you think the trends are referred to as being "PERIODIC." Hint the word periodical is sometimes used with magazines and newspapers that are delivered at regular intervals.

Blog 7.1 Flame Tests and Emission Spectra

Conclusion:

1.  After seeing the spectra of various elements in this lab, why do you think an element’s spectrum is often called its “fingerprint?”   Explain using the terms ground state, excited state, and electron configuration.

2. Explain how a spectra is formed. Make sure to include the process and the steps that occur. This is important that you can describe what happens during the changes between ground and excited state, and how energy is released and absorbed.

ENRICHMENT:

1.  Research the discovery of the element Helium, and why it is given the name it has.

2.  Find out how astronomers use what is called a “red shift” or a “blue shift” to know whether a galaxy is moving towards or away from our galaxy.  To do this:

a)  Explain what blue shifts and red shifts are, and what they have to do with an element’s spectrum.

b)  Explain how the ratio of blue shift to red shift galaxies is used as evidence that the universe is expanding.

c)  Find out what Sir Edwin Hubble had to do with all this.  

Lab 6.1 Double Replacement Reactions

In our lab we looked at many different scenarios where a double replacement reaction either resulted in no apparent change, or the formation of a precipitate.

First, take a look at your predictions. Where they all accurate? If not explain which ones did not match up. See if you can figure out what happened. There was one trial that had results that did not match up with the expected prediction. Where you able to find it, which one was it? What do you think the insoluble product was, this will go against what table F tells us!!

Write a procedure on how to write a double replacement reaction. You can do this with bullets or paragraph form. The steps that you must have include: finding and writing the formulas for the products, balancing the reaction, and finding the precipitate. Describe theses steps (and more if you need them in detail, don't just give me a list of what I just gave you!!)





Precipitation reactions are very important in water treatment and purification. Find a contaminant that is removed from waste water before it is processed back into nature using a precipitation reaction (hint do a google search). See if this reaction is consistent with the information on Table F (it depends on the ion that is used). Sulfate is an ion that is often used to form precipitates, using Table F why is this a good choice.

5.1 Rates of Reaction

Ok, so the last experiment that we did really focused in on the reasons that a reaction will proceed at a certain rate. The way that you will need to think about this process has to do with particle collisions and how they influence how fast the reaction will happen. For a reaction to happen we need what is called an effective collision. This means that the particles have collided in such a way that there will be a chemical reaction. The changes we made in the lab, influence the number of effective collisions that were occuring.

The first thing that we did in the lab was try to make a plan so that you could determine how the lab would be done so that you could tell how changing each variable would influence what happened. Describe quickly what you did in the experiment. Include in this description why it was important that you controlled the variables in a certain manner. Why was your procedure effective at determining how each variable influence on the rate? What would happen if you changed multiple variables at the the same time?

By changing the concentration of the vinegar, the temperature of the vinegar, and the amount that the tablet was crushed the rate of reaction was changed. Describe, using particle collisions why each variable changed the rate. Also describe if the results in your experiment were consistent with what you expected to happen. If they aren't, describe something that could have gone wrong in the process.

Enrichment: Do some online research and find an example of a real-life catalyst. Find out what changes in the reaction and how that has a significant influence on the rate of reaction. If you need help getting started catalysts are often used in industrial processes in order to make reactions more efficient. Also, you could look at enzymes and see specifically how they change a biological process.