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August 1, 2014

Homework Help: Science-Chemistry

Posted by Immy on Monday, September 13, 2010 at 7:49pm.

I did a lab on Elements and Compounds and I would be grateful if u could provide and tell me some information on my work.


Lab --Investigation--Elements and compounds.

Can an element be seperated from a compound? Can an element form a compound? In this investigation, you will attempt to prove that an element(hydrogen) can be seperated from a compound (hydrochloric acid), and that element will form another compound (water). To verify what is happening in your investigation, you will perform tests. The presence of hydrogen gas can be tested by placing a small sample into an inverted test tube and bringing a burning wood splint up to the mouth of the tube. Hydrogen gas will ignite and a popping noise will be heard. the presence of water can be tested by using cobalt(II)chloride test paper. when in contact with water, the blue test strips will turn purple.

Materials:

Safety goggles, 2 test-tubes, test tube stand, dilute hydrochloric acid in dropper bottle, laboratory scoop, zinc granules, wood splint, matches, cobalt chloride test strips.

Procedure:

1. read through the procedure and make a table to record ur observations.

2. Put on ur safety goggles, and then place the test tubes in the stand.

3. Carefully fill the bottom of one test tube with 2cm of dilute hydrochloric acid.

4. Pour one small scoop of zinc granules into the test tube. Quickly invert the second test tube over the top of the first.

5. Record ur observations of the reaction. What evidence of a chemical change was there?

6. After about 30 s, remove the top test tube and cover the end with ur thumb (Keeping it upside down)

7. Ignite the wood splint and holding the gas filled test tube down at a slight angle, remove ur thumb and carefully slide the burning splint into the mouth of the test tube. Hold on tight, so as not to drop the tube.

8. Record ur observations of the reaction. what evidence shows the presence of an element?

9. If a liquid forms inside the tube, test it with the cobalt (II) chloride test strips. record the results of this test.

10. Clean up ur workstation and dispose of the materials as directed by ur teacher.

My observations:

-Bubbles form
-Zinc reacts and the acid turns smoky white
-Gases at bottom of tube rising.
-As the gas was lit, it made noises.
-Flame burns hydrogen

(Any other things I need to add?)I wasn't really sure of how to explain what I was exactly seeing, so this is what I mainly got.

My answer to the following question:

Question: Can an element be seperated to form a compound? Can an element form a compound?

Answer: Yes, and element can be seperated to form a compound because hydrogen was seperated from the hydrochloric acid. An element can also form a compound because hydrogen was combined with Oxygen to form water.

I will post my Analysis questions on a different page, cause I think I've got too much on here already. Please read through this and tell me if whatever I have so far is correct. Other information would be greatly appreciated.

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