Write a description of how you know a chemical reaction is occurring.
A chemical reaction can be identified by the formation of new substances with different properties. Common signs that a reaction is occurring include a change in color, the production of a gas (bubbles), the formation of a solid precipitate, or a change in energy such as the release or absorption of heat or light.
Sample Response: Chemical reactions involve the chemical interaction of two or more chemical substances, result in a new substance being formed, and are usually irreversible. The signs of chemical reactions include gas formation, energy release in the form of light or flame, heat absorption, precipitate formation, and color change. Which did you include in your response? Check all that apply.Chemical reactions involve two or more chemical substances.Chemical reactions result in new substance for
✔ exothermicendothermicneither
exothermicendothermic✔ neither
Identify the chemical reactions as endothermic, exothermic, or neither.
✔ exothermicendothermicneither
Which indicator of a chemical reaction is shown in the picture?
Karina strikes a match to light a candle. Explain what type of reaction the burning match represents in terms of energy.
A burning match represents an exothermic reaction because energy is released in the form of heat and light during the chemical process.
When potassium iodide liquid is poured into lead nitrate solution (both clear solutions), a bright yellow solid, lead iodide, forms in a potassium nitrate solution. What are the signs that this is a chemical reaction? Check all that apply.
A food item that is left out of the refrigerator turns brown and forms bubbles and gas. What are the signs that this is a chemical reaction? Check all that apply.Heat is produced.Heat is absorbed.Bubbles appear.A precipitate forms.The color changes.
Theo mixes cake batter and places it in the oven at 350°F for 45 minutes. Explain what type of reaction baking a cake represents in terms of energy.
Baking a cake represents an endothermic reaction. This is because heat energy from the oven must be absorbed by the batter for the chemical reactions (cooking) to occur. In an endothermic reaction, energy is taken in from the surroundings.
Pure sodium metal placed in water will spark and ignite, as well as form bubbles and gas. What are the signs that this is a chemical reaction? Check all that apply.Heat is produced.Light is produced.Heat is absorbed.Bubbles appear. A precipitate forms.The color changes.
Sample Response: A burning match represents an exothermic reaction. The chemicals release energy in the form of heat and light as the reaction progresses. What facts did you include in your response? Check all that apply.Burning a match represents an exothermic reaction.Chemicals release energy in the form of heat and light.
Sample Response: Baking a cake requires heat to be applied to the batter in order for it to cook and chemically change into cake. The energy or heat applied is absorbed by the ingredients, so this represents an endothermic reaction. What facts did you include in your response? Check all that apply.Baking a cake requires heat to be added.The heat absorbed by the ingredients indicates that an endothermic reaction has occurred.
exothermicendothermicneither
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