Download Cool Chemical Reactions Lab Partners: Background Information

Name
Chemistry
Period X
Title: Cool Chemical Reactions
Lab Partners:
Background Information:
There are five types of chemical reactions. With synthesis, two or more elements come together to form
a single compound. The pattern for synthesis is A + B AB. With decomposition, a compound breaks apart
into two or more elements or less complex compounds. The pattern for decomposition is AB A + B. With
single replacement, a single element replaces another element in a compound. The pattern for single
replacement is A + BC AC + B. Metals replace metals and non-metals replace non-metals. With double
replacement, ions in a compound switch places with ions in another compound to make two new compounds.
The pattern for double replacement is AB + CD AD + CB. The last kind of reaction is combustion, where
an organic compound is burned with oxygen to form carbon dioxide and water. The pattern for combustion is
CXHY + O2 CO2 + H2O.
Hypothesis:
If the reactants in the chemical reactions are known, then the products can be predicted because the
pattern for chemical reactions is followed.
Materials:
“The Sparkler”
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Safety goggles
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Magnesium metal
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Bunsen burner
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Match
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Tongs
“Spy Writing”
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Safety goggles
•
Q-tips
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Small piece of paper
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Lead (II) nitrate solution
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Sodium iodide solution
“Fire Extinguisher”
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Safety goggles
•
Sodium bicarbonate
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Scooper
•
Test tube
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Test tube rack
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Splint
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Bunsen burner
•
Pipette
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3M HCl
“Hear It Pop”
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Safety goggles
•
Zinc flakes
•
Test tube
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Test tube rack
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Pipette
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3 M HCl
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Test tube stopper
Procedure:
“The Sparkler”
1. Put on safety goggles.
2. Observe the magnesium metal.
3. Make sure the Bunsen burner is lit.
4. Hold the magnesium with the tongs in the Bunsen burner.
5. Observe the magnesium in the flame by looking sideways.
6. Observe the burned magnesium.
7. Clean up.
“Spy Writing”
1. Put on safety goggles.
2. Dip one end of q-tip into lead (II) nitrate.
3. Draw with wet q-tip on paper. Let paper dry.
4. Dip another q-tip into sodium iodide.
5. Wipe end of q-tip over the paper.
6. Observe.
7. Carefully through q-tips and paper in trash.
“Fire Extinguisher”
1. Put on safety goggles.
2. Put two scoops of sodium bicarbonate in a test tube.
3. Light a splint in the Bunsen burner.
4. Add one pipette of HCl to the test tube.
5. Put the lighted splint just inside of the test tube.
6. Observe.
7. Clean up.
“Hear It Pop”
1. Put on safety goggles.
2. Put 2 or 3 pieces of zinc in a test tube using a scooper.
3. Add one pipette of HCl into the test tube and put a stopper in the test tube.
4. Light a splint.
5. Remove the stopper and put the splint just inside of the test tube.
6. Observe.
7. Clean-up.
Data:
“The Sparkler”
Before: The magnesium metal piece was shiny silver in color and it was malleable.
During: It took a while for the magnesium to burn. When it started to burn, it was orange and there was
sparks. Then it turned bright white.
After: The magnesium was dull, gray and ashy. It was no longer malleable and instead broke into
pieces.
“Spy Writing”
Before: Both the lead (II) nitrate and the sodium iodide solutions were clear. The sodium iodide was
pale yellow and the lead (II) nitrate was colorless.
During: When the lead (II) nitrate was used to write on the paper, the writing was still clear. After the
paper dried, you couldn’t see anything. When the sodium iodide was rubbed on the paper, the drawing
turned yellow.
After: After the paper dried again, the drawing was still yellow but there also seemed to be some yellow
chunks on the paper.
“Fire Extinguisher”
Before: The sodium bicarbonate was a white powder. The HCl was a clear liquid.
During: When the HCl was added to the sodium bicarbonate it bubbled a lot. When the splint was put
in the test tube, the flame went out.
After: The mixture in the test tube continued to bubble.
“Hear It Pop”
Before: The zinc was a whitish, gray metal in rock-like chunks. The HCl was a clear liquid.
During: When the HCl was added to the zinc it bubbled a lot and the test tube was warm. When the
splint was put in the test tube, a pop sound was heard.
After: The mixture in the test tube continued to bubble. The liquid was a grayish color.
Analysis:
“The Sparkler”
Magnesium reacts with Oxygen in the air to form magnesium oxide.
2 Mg + O2 2 MgO
“The Sparkler” was a synthesis reaction because it started with two elements and there was a single product. It
followed the pattern A + B AB.
“Spy Writing”
Lead nitrate reacts with potassium iodide to form lead (II) iodide and sodium nitrate.
Pb(NO3)2 + 2 NaI PbI2 + 2 NaNO3
The “Spy Writing” experiment was a double replacement reaction because the reaction started with two
compounds and there were two products. It followed the pattern AB + CD AD + CB.
“Fire Extinguisher”
Sodium bicarbonate reacts with hydrogen chloride to from water and sodium chloride and carbon
dioxide.
NaHCO3 + HCl H2O + NaCl + CO2
The “Fire Extinguisher” experiment was a double replacement reaction because the reaction started with two
compounds but there were three products instead of two. It kind of followed the pattern AB + CD AD + CB.
“Hear It Pop”
Zinc reacts with hydrochloric acid to form zinc chloride and hydrogen gas.
Zn + 2 HCl ZnCl2 + H2
The “Hear It Pop” experiment was a single replacement reaction because the reaction started with one
compound and one element and the products were also one compound and one element. It followed the pattern
A + BC AC + B.
Conclusion:
The hypothesis for this lab was that if the reactants in the chemical reactions are known, then the products can
be predicted because the pattern for chemical reactions is followed. The hypothesis was supported because in
each of the experiments, the type of reaction could be found and that helped determine what the products of the
reaction were based on the reactants.
The types of reactions that were seen in this lab were synthesis, single replacement and double replacement.
With synthesis, two or more elements come together to form a single compound. The pattern for synthesis is A
+ B AB. Synthesis was seen in the “The Sparkler” experiment. With single replacement, a single element
replaces another element in a compound. The pattern for single replacement is A + BC AC + B. The “Hear
It Pop” experiment was an example of single replacement. With double replacement, ions in a compound switch
places with ions in another compound to make two new compounds. The pattern for double replacement is AB
+ CD AD + CB. Both the “Fire Extinguisher” and the “Spy Writing” experiments were examples of double
replacement.
Some errors in the experiment occurred when the directions weren’t followed correctly. In the “Fire
Extinguisher,” the sodium bicarbonate got on the side of the test tube so when the HCl was added, it bubbled up
out of the test tube and made a mess. This made it difficult to but the splint in. Putting too much zinc in the test
tube in the “Hear It Pop” experiment made too much gas so the stopper came off the test tube before the splint
was lit. Following the instructions more carefully would help eliminate these errors.