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For a classroom demonstration, a chemistry teacher puts samples of two different pure solid powders in a beaker. The teacher places the beaker on a small wooden board with a wet surface, then stirs the contents of the beaker. After a short time the students observe that the bottom of the beaker is frozen to the wood surface. The teacher ask the students to make a claim about the observation and justify their claims. Which of the following is the best claim and justification based on the students observation?
For a classroom demonstration, a chemistry teacher puts samples of two different pure solid powders in a beaker. The teacher places the beaker on a small wooden board with a wet surface, then stirs the contents of the beaker. After a short time the students observe that the bottom of the beaker is frozen to the wood surface. The teacher ask the students to make a claim about the observation and justify their claims. Which of the following is the best claim and justification based on the students observation? A) an exothermic chemical change occurred because hea flowed from the contents of the beaker to the room.
B) An exothermic physical change occurred because the heat flowed from the contents of the beaker and the water on the board to the room.
C) An endothermic physical change occurred because the freezing of water is an endothermic process.
D) An endothermic chemical change occurred because the temperature of the beaker and the water on the board decreased as heat was absorbed by the reaction.
Final answer:the beaker's freezing indicates an endothermic chemical change where heat is absorbed, leading to a temperature decrease and water freezing. so the correct option is D) An endothermic chemical change occurred because the temperature of the beaker and the water on the board decreased as heat was absorbed by the reaction.Explanation:The best claim and justification based on the student's observation that the beaker became frozen to the wood surface after mixing two different pure solid powders is An endothermic chemical change occurred because the temperature of the beaker and the water on the board decreased as heat was absorbed by the reaction. This observation is consistent with the behavior of an endotheric process, where energy is absorbed from the surroundings, causing a decrease in temperature which allowed the water to freeze....