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.