Evidence of Chemical Reactions: PECSB
Chemical Reaction- a chemical change occurs when atoms rearrange and bond to form new products with different properties.
Exothermic Reaction- a chemical reaction in which energy is released therefore temperature increases
Endothermic Reaction- a chemical reaction in which energy is absorbed resulting in temperature decrease
Evidence of a Chemical Reaction has occurred:
Please
P
Excuse
E
Coughs
C
Sneezes
S
Burps
B
Demonstration: It’s all a Glow
1.
What are the physical properties of the liquids before they are mixed together?
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2. What happened when the two liquids were mixed together?
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3. Did a chemical reaction occur? If so, what is the evidence of a chemical reaction.
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Demonstration: Sunshine in a Bag
1. What are the physical properties of the reactants before they are mixed together?
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2. What happened when the two reactants are mixed together?
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3. Did a chemical reaction occur? If so, what is the evidence of a chemical reaction.
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4. In this reaction, how could you determine that the mass of the reactants equals the mass of the
products (law of conservation of mass).
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Station 1: Blowing up Balloons without the Sore Jaw!
Substance
Physical Properties
Observed Changes
Baking Soda
Vinegar
1.
Is there evidence of a chemical reaction? How do you know?
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2. What are the reactants in this experiment?
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Station 2: Secret Messages
1. What did you observe when you put the paper with message over the hot plate?____________
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2. Is it possible to reverse this change? _________________________________________________
3. What did you have to do to initiate the change? ________________________________________
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4. Was this a physical or chemical change? Justify your answer.___________________________
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Station 3: Red Light-Green Light
Ammonia
(NH3)
Acetic Acid
(CH3COOH)
Cabbage Juice
Cabbage Juice
Cabbage Juice
Universal Indicator
+ Ammonia
+ Ammonia
+ Acetic Acid
Observations
(what do you
see, smell,
etc.?)
1.
What elements are present in the chemical formula for ammonia ( NH3)?
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2. How many atoms of each element are present in ammonia ( NH3)?
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3. Observe what happens after you mix the acetic acid (CH3COOH) and ammonia ( NH3) + universal
indicator. Describe what you observed.
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Station 4: Witches Brew
1.
Observe what happens. Record your observations.
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2. The following equation shower the witches brew reaction:
CH3COOH + NaCHO3→ NaCH3COO + H2CO3
Circle the reactants in the above chemical equation.
Underline the product in the above chemical equation.
Box the yields sign.
3.
Does this equation follow the law of conservation of mass?
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Station 5: Curds and Whey
1.
Observe what happens. Record your observations.
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2. Did a chemical reaction occur? How do you know?
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3. What elements are present in acetic acid (CH3COOH)?
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4. How many atoms of each element are present in CH3COOH?
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Station 6: Were making Pancakes!
1. What are the 5 evidences of a chemical reaction?
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2. Which of these did you observe that proves a chemical reaction occurred?
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Station 7: Feel the Heat
1.
Starting temperature of the hydrogen peroxide __________
2. Record the temperature in your beaker every minute for 4 minutes.
Minutes
1
2
3
4
Temperature
3.
What happens to the mixture of the 4 minutes?
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4. What do the sides and bottom of the beaker feel like?
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5. What do you think was being produced when the hydrogen peroxide and yeast were mixed?
EXPLAIN._______________________________________________________________________
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6. Why did the temperature change?
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7. Are the results of this experiment an example of a physical or chemical change? EXPLAIN WHY.
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