Monday, September 13

We started class today with Mr. Henderson telling us to get out our calculators, lab notebooks, packet, and to make sure we had patience. We began class by reviewing Lab MM6, the Conservation of Mass Lab. During this lab, we measured the mass of chemicals before and after a chemical reaction. The purpose was to figure out if mass was retained or changed during a chemical change. One person from each lab group went to the front of the room to record their data so we could see what the overall data of the entire class was. This is what the class data turned out be:

We then discussed whether or not the results of the lab shows that mass is retained during a chemical change. Some people said that mass was lost, since some of the masses decreased lightly. Others said that the mass stayed the same because it only changed slightly. Mr. Henderson told us that the mass had stayed the same. He said that in chemistry, 157.37=157.21. This could be because of the uncertainty or some of the chemicals may have fallen out when it was measured for the second time.

Once we finished reviewing the lab, we started to learn about metric conversions. We were told we had to memorize four of the prefixes. We learned a great way to remember them.

1 kilometer=1000 meter

100 centimeters= 1 meter

1000 millimeters=1 meter

10^9 (1,000,000,000) nanometers=1 meter

We also learned a way to remember the many different prefixes by using a scale.

We learened how to use this scale to do metric conversions. If you wanted to convert a kilometer to a meter, you move the decimal place 3 places to the right since the base unit is 3 spaces to the right of the kilo. If you wanted to convert millimeters to meters, you move the decimal place 3 places to the left since the base unit is 3 units to the left of the milli. We practiced doing this by doing a worksheet, page 7 in the packet.

We then went over problems 7 and 8 form the worksheet. 7 was converting 1 mL to kL. First we learned to convert it to L. If you move the decimal place 3 to the left, you get 0.001 L. If you move that 3 more places to the left, you get 0.000001 kL. for 8, the problem was to convert 1.0 Mg to mg. Mg was not on the scale, but it was listed on the worksheet as 10^6. If you calculate 1.0 X 10^6, you get 1,000,000 g. It still needs to be put into mg from g, so you move the decimal place 3 spaces to the right. The solution to that is 1,000,000,000 mg (10^9 mg).

We finished class by being assigned our homework to do a Webassign reading sheet for tomorrow and our Delicious Assignment, which is due on Friday. Overall, it was a very productive class.

Tuesday, September 7

Today in Chemistry, we mainly focused on measurements. We began the class by reviewing the assignments. Mr. Henderson reiterated that Labs 1-4 and packet pages 3 and 4 are due tomorrow, Wednesday September 9; and the Intro to Measurement Lab is due on Wednesday. He then proceeded to discuss the lab from yesterday, the MM4 Separating Mixtures Lab. He used a similar (example) lab about coins to demonstrate how to find the percent composition of each element in a mixture. First it is needed to find the total mass of the mixture, and then the mass of the element whose composition you wish to find. Then, you divide the mass of the element by the total mass, and you have the percent composition of that element. Mr. Henderson multiplied the number present of each coin by the mass of that type of coin, then divided the total mass of the coin mixture to find the percent of coins which make up the mixture. He then gave us time to This link describes how to find the percent composition:
http://www.chem.tamu.edu/class/majors/tutorialnotefiles/percentcomp.htm


Next, we began the Intro to Mixtures lab, which taught us about the precision of different instrument (with some divisions), and a graduate (with many divisions). Then we had to measure the length of a blue pen with multiple rulers that had various degrees of divisions. Through these two experiments, we found out that the instruments with less divisions force you to estimate more, and therefore be less precise. After that, we weighed the mass of a penny using three different mass balances, which gave slightly varying numbers. We then discussed significant digits, which are important when communicating the precision of our measurements. Mr. Henderson stated that in regards to significant figures, one figure is one that is always estimated. In other words, it can be assumed that all of the digits are exact up until the last one (and it is important to do this when measuring something yourself in order to communicate it to others).
This link is very helpful in understanding the concept of the degree of uncertainty:
http://www.tutorvista.com/content/chemistry/chemistry-iii/chemistry-concepts/uncertainty-measurement.php

^^These are the different instruments we used to measure the volume of water.

Mr. Henderson today emphasized the importance of the difference between mass and weight. He clarified that mass is the amount of matter one object has, and gravity is the force which acts on that amount of matter. He gave the example that if a person were to go to outer space, they would have a different weight (because different planets have different amounts of gravity), but his/her mass would remain the same. He also pointed out that our scales in Chemistry calculate mass, whereas typical scales calculate weight.
This is a really good link that describes the difference between mass and weight:
http://www.colorado.edu/physics/2000/periodic_table/mass.html

Overall, today was a very informative day in Chemistry; and we learned much about measurements. Don't foget about the pop quiz on Friday!

Wednesday, September 8, 2010

Today's class started off as usual while discussing the blog from the previous day even though we weren't able to view Hannah's blog post because she wasn't able to post it online. Mr. H gave us a general overview on what we need to successfully post a blog online. Mr. H told us that we also have to make sure to join the blog, so that we have the ability to post on it.

We then looked at lab MM5 titled the Chemical Properties Lab. Mr. H put up the page in the Unit
1 packet, which had the guidelines for the lab on the page. While the whole class begins writing the purpose of the lab, Mr. H stresses the safety precautions associated with the lab. Sodium hydroxide and hydrochloric acid can cause damage to the eyes and the skin, Ammonium hydroxide vapors can be hazardous to the lungs. Cupic chloride is toxic, but only when ingested. Magnesium and Zinc dust are flammable. We had to keep these mind, while doing the lab. Mr. H also told us the procedure of this lab where we were going to be determining the chemical properties of hydrochloric acid and copper chloride.


Before we began the lab, Mr. H reviewed with us how to precisely write down the measurements when reading a graduated cylinders. We have to make sure to measure to greatest degree of certainty. Basically that means one should record all digits that are certain and one additional estimated digit. What is important to remember is that the degree of certainty depends on the precision of the measuring device.
Mr. H then has us continue on to the next page where we learned about counting the number of significant zeros in a measurement. The number of significant zeros in a measurement reveals the degree of certainty of the measurement. Mr. H taught us the following four rules

A. All non-zeros digits are considered significant
B. For zeros:
1. Leading zeros(those which precede non-zero digits) are never significant
2. Captive zeros(those surrounded by non-zero digits) are always significant
3. Trailing zeros(those which come at the end of the number) are significant only if there is a decimal point listed in the number.
After explaining the rules with a brief explanation, Mr. H lead us in an significant number excercise where we had to determine the number of significant numbers.
Once we completed working on the worksheet we began the lab. The lab required us to have a set up where we placed hydrochloric acid and copper chloride in a tray with 4 rows of 6 containers. We were to determine the chemical properties of hydrochloric acid and copper chloride when mixed with other substances. The pH level of the hydrochloric acid was tested. Also, another substance mixed with the hydrochloric acid was an Aluminum shot, Zn mossy, and Magnesium. Same goes for the copper chloride. We recorded the reactions to each test that was performed in our lab notebook.


This video was the set-up to the lab where hydrochloric acid and copper chloride where each put into separate rows.







In this video Mr. H placed Ammonium hydroxide in the hydrochloric acid and copper chloride.

In the closing moments before class, Mr. H assigned the homework. We were to begin on the web assign, prepare for our 'pop quiz' and finish the measurements lab.

Friday, September 3, 2010

Todays class period was a rather unique one, but it started off the same as usual before it got interesting. We viewed Emma's blog in which she did an excellent job. Mr. Henderson then explained to us the photo situation. The photos that we would take on his camera for the blog would be on a website called dropshots.com.

We then looked at lab MM4. Separating Mixtures Lab and wrote down the purpose. Mr. Henderson then had us turn to page 18 in our Chemistry Basics packet to learn how we could separate sand, salt, and iron. It said that each method relies on the fact that the components have different physical properties which can be used in separation method.

To show us how this all worked, Mr. Henderson showed us a very fun and original demo. He talked about how sand had many variables in itself and could be split up into rocks, little pebbles, fine sand, and super fine sand. He used different sized screens to split these variables up going from the biggest openings to the smallest. As he started to 'shake it up,' he danced to one of his favorite songs by KC and the Sunshine Band. http://www.youtube.com/watch?v=8GtGY6tuDaA&feature=fvst

After that attention-grabbing demo, our class began the lab by weighing or finding the mass of the mixture by using the zero, or tare button. The mixture consisted of salt, sand, and iron and was a heterogeneous mixture because we could visibly see the differences in the substances. We then had to figure out how to separate them. First, we used a magnet to separate the iron because iron is magnetic. Next, we poured the rest of the mixture into water because we knew that salt was soluble, and we could filter out the sand. This is exactly what we did. We poured the mixture of sand, salt, and water through filter paper and a funnel which left behind the sand.

After that, we put the filter paper with the sand on a hot plate to dry it off. We did this because when we would weigh the sand to figure out its mass, we would not want to have water be part of that mass too.

We then weighed the iron and the sand to find out the mass in grams. To find the mass of the salt we subtracted the weight of iron and sand from the weight of the total mixture. We did this because salt was the only substance remaining so it would have to have the remaining weight of the mixture. For example, if the mixture weighed 2 grams, the iron weighed 0.24 grams, and the sand weighed 0.46 grams, then the salt would have to weigh 1.30 grams because 2 - (0.24+0.46) = 1.30. Furthermore, we calculated the percent of the salt, sand, and iron in the mixture by dividing its weight by the total weight of the mixture and multiplying it by 100. After doing that math, we wrote down our conclusion.

Class time was running out, and the Web Assign homework was assigned. We all left class 'shaking our booties' as Mr. Henderson put the song back on for the last couple minutes of class.

Thursday, September 2, 2010

Today was a rather average day in Chemistry Class. Mr. Henderson began by taking attendance and then going over the blog post done by Dmitriy from the previous day. Mr. Henderson then explained our homework due Tuesday more thoroughly. The homework was a 1.1 WebAssign on the Classifications of Matter. Mr. Henderson explained how the questions worked and how for some questions you received multiple chances to get them correct.

We then moved on to pages 1 and 2 in our Unit 1 packets. Page 1 and the first half of page 2 were about the symbolic language of mixtures. For the first group we were given a drawing of a substance and asked how many types of atoms were in it and how many types of compounds were in it. Then in part 2 we were given a diagram of the substance, and the symbol for it. We were then asked to describe the substance using words like atom, compound, molecule, element, etc...

The bottom half of page 2 was about the interpretation of mixtures. We were given long symbols for a substance and were asked how maybe elements and compounds there were, as well as the total number of atoms and the total number of molecules. This part was the most difficult for the class to understand.

We finished class up with Lab MM3 or the Salt, Sand, and Iron Lab. The purpose of the lab was to distinguish between salt, sand, and iron on the basis of their physical characteristics. We began by just observing the three substances and recording their color, granular size, and texture. Next we tested each of the item's magnetic properties by moving a magnet over each and seeing how it reacted. My lab group discovered that only iron had magnetic properties and that they were very strong. Next we tested the solubility in water of each substance by adding a little bit of each to a test tube of water and mixing it around. My group found that only salt dissolved in the water and the other two just sunk to the bottom.

Class today was very fun and very educational. The lab was a great way to test properties and it was great to have more practice on the types of matter.