Rates of Chemical Reactions
1. Watch the video of Volcano Experiment involving ammonium dichromate. How is heat involved in this chemical reaction? ______
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2. Does the temperature of reactants affect the rate of chemical reaction? How do you know this? ______
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3. On the molecular level, why do you think warm solutions react faster than the cold solutions? ______
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The rate of a chemical reaction is a measure of how fast the reactants are changed into products. This can be increased by increasing the temperature of the reactants.
For reactant molecules to react, they need to contact other reactant molecules with enough energyfor atoms or groups of atoms to come apart and recombine to make the products. If they donot have enough energy, most reactant molecules just bounce off and do not react.
But if the reactants are heated, the average kinetic energy of the molecules increases. This meansthat more molecules are moving faster and hitting each other with more energy. If more moleculeshit each other with enough energy to react, then the rate of the reaction increases.
Another way to increase the rate of the reaction is by adding a substance that helps bring the reactants together so they can react. A substance which helps speed up a chemical reaction in this way but does not become a product of the reaction is called a catalyst.
4 What are two ways that you can speed up chemical reaction? ______
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5. What is a catalyst? ______
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6. If a catalyst is involved in the chemical reaction, why isn't it included as a product in the chemical equation? ______
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Salton Sea #1
Watch the video "Saving the Salton Sea" and write 3 Observations
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Write 3 questions ______
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2. Create a timeline of events at the Salton Sea
3. Why do you think fish are dying at the Salton Sea? ______
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4. Should the Salton Sea be saved? Why or why not. ______
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5. How would you prevent the fish from dying at the Salton Sea? ______
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Salton Sea #1
The Salton Sea is a shallow, saline lake located 226 feet below sea level, occupying the lowest elevations of the Salton Sink in the Colorado Desert of Imperial and Riverside counties in Southern California. With an average surface area of 1,360 square km, it is the largest lake in California. Yet, just a century ago, the lake didn’t even exist.
The Salton Sea was a vast geological depression, a dry bed, that was often referred to as the “Colorado Desert” throughout the Spanish period of California's history. A flood in 1905 poured the Colorado River into the sink, and by the time authorities managed to stop the flooding two years later, the largest lake in California had already formed.
Intermittent flooding of the Imperial Valley by the Colorado river continued. Eventually it led to the construction of Hoover Dam in the 1930s and the flooding finally stopped. Salton Sea is now fed by the New, Whitewater, and Alamo rivers, as well as agricultural runoff, drainage systems, and creeks. The average annual inflow of 1.68 cubic km is enough to maintain a maximum depth of 52 feet and a total volume of about 9.3 cubic km.
In 1950, the California Department of Fish and Game released thousands of fish into the Salton Sea. A few species survived and Salton Sea quickly became a fisherman’s paradise. With new fish to eat, the Sea also became a new stopover point for migratory birds. Over 400 species have been documented at the Salton Sea. Around 30% of the remaining population of the American white pelican lives in its shores, and the lake is also a major resting stop on the Pacific Flyway.
Salton Sea’s economic boom however didn’t last long. Since the Salton Sea has no outlet, the salt and chemicals dumped by agricultural runoffs and industries began to rise while the water level remained the same. Over the years, fish began to die in large masses - tens of thousands of dead fish and birds began regularly washing up on the shore of the Salton Sea. When in the summer of 1999, 7.6 million Tilapia died from oxygen starvation caused by the overabundant algae, the authorities knew the situation was grim. Their rotting carcasses rimmed parts of the Sea for over ten years. Combined with the decaying algae, the smell was overwhelming.
1. Summarize the problems at the Salton Sea. ______
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Energy Change in Chemical Reactions
Watch the video of Baking Soda and Vinegar (Endothermic Reaction). Why do you think the temperature went down when Baking Soda reacted with Vinegar.
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2.Watch the video of Exothermic and Endothermic Reaction Demonstration. Explain which reaction was exothermic and which reaction was endothermic.
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3. Draw a Cartoon strip of a Exothermic Reaction
4. Draw a Cartoon strip of a Endothermic Reaction