CH 7 HW PART 2.pdf - CH 7 HW PART 2 Due 11:59pm on Sunday...

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CH 7 HW PART 2 Due: 11:59pm on Sunday, October 15, 2017 To understand how points are awarded, read the Grading Policy for this assignment. Signs of a Chemical Reaction A chemical reaction is a process by which one or more substances transform into different substances via a chemical change. Sometimes, chemical reactions exhibit evidence that can be easily observed when they occur. Part A Which changes are evidence of a chemical reaction? Drag each item to the appropriate bin. Hint 1. Physical changes and chemical changes In a physical change , matter does not change its composition, although the appearance of the matter changes. For example, a physical change occurs when liquid water freezes, producing ice. The water does not change its composition: Liquid water and solid water (ice) are both composed of water molecules. In a chemical change , matter does change its composition. For example, when iron rusts it forms iron oxide. The iron changed composition: The iron formed iron oxide. Hint 2. Identify possible evidence of a chemical reaction Which of the following are possible evidence of a chemical reaction? Drag each item to the appropriate bin. Hint 1. The definition of precipitate A precipitate is an insoluble product formed through the reaction of two solutions containing soluble compounds. ANSWER: Hint 3. Identify examples of physical and chemical changes Classify each of the changes as a physical change or a chemical change. Drag each item to the appropriate bin. ANSWER: Help Reset temperature increase temperature decrease color change emission of light precipitate formation bubble formation Might indicate a chemical reaction Never indicates a chemical reaction
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ANSWER: Correct The bubbles forming on calcium carbonate chalk in a hydrochloric acid solution are a result of the chemical reaction The bubbles in a shaken soda bottle are simply carbon dioxide bubbles being released from a pressurized solution supersaturated with carbon dioxide. Part B In a lab, silver nitrate, , is dissolved in water until no solid is observed in the container. Then, a solution of sodium chloride, , is added to the container. When you combine these aqueous solutions, there is no noticeable change in temperature; however, a solid precipitates and there is a slight change of color. Help Reset Help Reset bleaching hair iron rusting burning wood chopping wood condensing steam Two clear solutions are mixed and form a cloudy solution. Bubble formation on chalk added to acid A beaker of water becomes cool to the touch upon adding a salt to it. Bubbles forming in a pot of boiling water Ethanol evaporating Chemical change Physical change Evidence Not evidence
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Which statements about the lab experiment involving silver nitrate and a sodium chloride solution are true?
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