Lab 3: Detecting Signs of Chemical Change 3. Based on your observations of the l
ID: 530742 • Letter: L
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Lab 3: Detecting Signs of Chemical Change 3. Based on your observations of the laboratory assignmentos that produced gases, can you conclude that the same gas was produced in each assignment? Briefly explain. 4. Based on your observations of the laboratory assignment(s) that resulted in a color change, can you conclude that: (1) Precipitate formation is always accompanied by a solution color change? Briefly explain. (2) A precipitate must form in order for a color change to occur? Briefly explain 5. Based observations of the laboratory assignment(s) that resulted in heat changes, can you on your reaction? Briefly explain. conclude that heat is always released in a chemical custom pageExplanation / Answer
3.A gas evolution reaction is a chemical process that produces a gas, such as oxygen or carbon dioxide. In the following examples, an acid reacts with a carbonate, producing salt, carbon dioxide, and water, respectively.
Nitric acid reacts with sodium carbonate to form sodium nitrate, carbon dioxide, and water.
Sulfuric acid reacts with calcium carbonate to form calcium sulfate, carbon dioxide, and water.
Hydrochloric acid reacts with calcium carbonate to form calcium chloride, carbon dioxide, and water.
4. (a) No...they salt formed can be colorless or the same color as the solution just because it forms a salt doesn't mean the salt will change the color of the solution.
(b) if you have CuSO4(aq) and you add excess NH4OH, then you get a color change from greenish blue to what I call "electric blue," which is an intense blue with a little purple in it. If you add excess concentrated HCl(aq) to CuSO4(aq), you get green.
Also, if you dip a Zn(s) strip into CuSO4(aq), you get Cu(s) plating out on the Zn without having mixed two solutions.
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