12. A 15.7-g sample of sodium carbonate isadded to a solution of acetic acid weighing 19.4g. The two substances react, releasing carbon dioxide gas to theatmosphere. After reaction, the contents of the reaction vesselweighs 28.4 g.
What is the mass of carbon dioxide given off during thereaction?
13. Cadmium metal reacts vigorously with yellowcrystals of sulfur to produce a yellow powder ofcadmium sulfide. A chemist determines that112 g of cadmium reacts with 32.1g of sulfur. How much cadmium sulfide could beproduced from 45.4 g of cadmiummetal?
18. Pick if it is a chemical or physcial reaction
| (a) Pure water is obtained from ocean water byevaporating the water, then condensing it. | | physical process | | chemical reaction |
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| (b) Mercury is obtained by heating the substancemercury(II) oxide; oxygen is also obtained. | | physical process | | chemical reaction |
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| (c) Zinc is produced through the electrolysis ofaqueous zinc sulfate | | physical process | | chemical reaction |
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| (d) Gold is obtained from river sand by panning(allowing the heavy metal to settle in flowingwater). |
