Guest Posted January 15, 2016 Report Share Posted January 15, 2016 Please help me understand why the answer is D. Reply Link to post Share on other sites More sharing options...
kw0573 Posted January 15, 2016 Report Share Posted January 15, 2016 (edited) If ice-melting and ice-forming have equal rates, the system would be in equilibrium. Since we see ice-melting predominantly, or on a macro scale, we say the rate of ice-melting favours, hence the system is not in equilibrium. Edited January 15, 2016 by kw0573 Reply Link to post Share on other sites More sharing options...
Guest Posted January 15, 2016 Report Share Posted January 15, 2016 If ice-melting and ice-forming have equal rates, the system would be in equilibrium. Since we see ice-melting predominantly, or on a macro scale, we say the rate of ice-melting favours, hence the system is not in equilibrium. For example, if you have a beaker of water that is 0 degrees C and you put 0 degrees C of ice (hard to measure temperature of ice, but assume it is 0) into the beaker the ice will not melt. The melting point of water, by definition, is the temperature of the equilibrium between ice-melting and ice-forming (condensation). Ok, however, puiting a 0C ice in 0C water, the ice is not melting, wouldn't that be at equilibirum because the tempertaure for both substances aren't changing? Reply Link to post Share on other sites More sharing options...
kw0573 Posted January 15, 2016 Report Share Posted January 15, 2016 I made an error so I deleted the latter part. The melting point is the defined by pressure, not by rates.As long as the ice is macroscopically not melting and not increasing in size, dynamic equilibrium has been reached.In the original question, ice IS melting. We physically see the ice shrink, so the system is not in equilibrium. Reply Link to post Share on other sites More sharing options...
kw0573 Posted January 15, 2016 Report Share Posted January 15, 2016 Choice A is false. This is a closed system neglecting heat loss. Choice B is false. Equilibrium can be approached from either side. The names "products" and "reactants" depend on what the "forward reaction" is written as. If you write the reaction the other way, products and reactants would have simply swapped. Choice C is false. Because H2O (s) ---> H2O (l) is endothermic, the temperature of the environment, which is the liquid decreases. Conversely, the temperature of the ice cube increases.Choice E is false or irrelevant. No information is given about pressure. In generally in a small closed container air pressure can be assumed to be constant, because evaporation of water can only occur until the the air is saturated. Pressure in water is constant as water cannot be compressed (noticeably). Reply Link to post Share on other sites More sharing options...
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