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Indicators of chemical reactions
Formation of a gas
Emission of light or heat
Formation of a precipitate
Color change
Emission of odor
OBSERVING CHANGES OF MATTER
• MATTER – Anything that has mass and
takes up space
• CHEMISTRY –The study of matter and how it
changes
T = Properties and Changes of Matter
Properties of Matter ― Physical Property ―Characteristic of a substance that
can be observed without changing the substance into another substance ―Examples – ―Melting point, color, Luster, texture,
Hardness, flexibility
T = Properties and Changes of Matter
Properties of Matter ―Chemical Property ―Characteristics of a substance
that describes its ability to change into other substances. •Examples –Burning, Rusting, Tarnishing (patina)
Chemical Properties! IDEAS?
Burning • Burnt Marshmallow • Bread to toast • Cookies in the oven • Firewood • Grass fire • ? Candle ? • Definition?
– React with Oxygen while heated!
Rusting • Bike frame • Bike Chain • Outdoor light fixtures • Lawn furniture
What RUSTS?? HOW? anything with Iron (Fe) in it!! Reacts with oxygen in water!
TARNISH?? Metal + Oxygen or
a Sulfide
T = Properties and Changes of Matter
Changes of Matter ―Physical Change ―Consists of any change which alters
the appearance or form without changes is chemical makeup changing it into another substance.
―Examples ― change of state (solid, liquid, gas),
shape, bending, crushing, cutting (ie-braiding hair)
T = Properties and Changes of Matter
Changes of Matter ―Chemical Change (chemical
reaction)
―Matter changing into a new substance
― examples, burning gasoline, burning magnesium, baking a cake
Student Activity - Classifying
Physical Change
Chemical Change
A. Piece of metal is heated until it changes to a liquid B. Two clear solutions mixed. A yellow powder forms and settles to the bottom C. Water left in a dish overnight has disappeared by the next day D. A blacksmith hammers a piece of red-hot iron into the shape of knife blade.
T = Properties and Changes of Matter
Bonding and Chemical Change ―Chemical changes occur when bonds
break and new bonds from - Review
- Bonds made by sharing or transferring electrons (what types of bonds are these?)
- Covalent vs Ionic
― O2 (in air) + Mg metal
T = Evidence of Chemical Reactions
Changes in Properties ―Precipitate
― Solid from solution ―Color Change ―Production of gas ―Change in moisture content ―Hardening
T = Evidence of Chemical Reactions
Changes in Energy — Types - Heat, light and electricity — Reaction - Absorption or release of energy ―Endothermic
― Absorption of energy (cold to touch)
―Exothermic ― Release of Energy (warm to touch)
Student Thoughts!!
Exothermic Reactions (feels warm)
Gives of Heat/Energy
• Digestion
• Burning Fuel
• Hand warmers
Endothermic Reactions (feels cold)
Absorbs Heat/Energy
• Photosynthesis
• Chemical cold pack
Assessment Questions
•
Writing a Conclusion – Power Outline
• T = Hypothesis
What happened-the results
Details—Description
Details-
Details
Hypothesis right or wrong or somewhere in between.
Details- The why!!!! (Y)
Details-
Details
Conclude with thoughts of what was made! What are your results.
Conclusion Part 2
When the sugar is heated it will come together and harden because it was a chemical change. When the sugar was heated it melted and turned brown then hardened. The sugar emitted a sweet scent. It turned a little translucent and slightly amber in hue. While it smelled sweet it also smelled slightly bitter. Our hypothesis was partially correct. The sugar turned hard but we did not think about the color change. We also did not anticipate the change in the fumes of the sugar. As the sugar was heated it carmalized and thickened.
Power Outline – 5 th Period • T= Hypothesis
The Results –What Happened-What it saw
Details –Description
Details
Details
Hypothesis- Right, Wrong, Somewhere in between
Details – what was right
What was wrong
What was missed
Propose product – what do you think the results or products is/are? Details – why? Your reasoning.
Conclusion Part 2 (P5)
If we heat the sugar, the sugar would melt because of the chemical reaction. Our lab results showed a change of color and precipitation. The sugar hardened and turned brown. It also bubbled. The aluminum turned black and candle wax melted. It smelled like the taste of a smore. Our hypothesis was correct regarding a physical change. However, it hardened, changed color and had a different smell. There was a chemical change because of the change color and smell and hardness of the browned sugar. We conclude that the sugar carmalized.
Skills Lab
• Where is the Evidence?
• PRELAB in Class. Fill out lab worksheet. Problem. Materials, Procedure, and table preparations.
• Lab – write the procedure as it is accomplished. Write down all observations in the table.
• Answer questions 1-7
• Formulate a conclusion for the lab .