Chemistry, 22.07.2019 01:30 uwunuzzles

Questions 18-20 refer to the reaction 2nh3 (g) ↔ n2 (g) + 3h2 (g), and δh = 92.2 kj. what will be the effect on the concentration of h2 if the temperature decreases? a. h2 concentration will decrease. b. h2 concentration will not change. c. h2 concentration will increase. d. h2 concentration will not change, but δh will decrease e. h2 concentration will not change, but pressure will increase. what will be the effect on the concentration of nh3 if the pressure decreases? a. nh3 concentration will decrease. b. nh3 concentration will not change. c. nh3 concentration will increase. d. nh3 concentration will not change, but δh will decrease. e. nh3 concentration will not change, but entropy will increase. what will be the effect on n2 if the concentration of nh3 increases? a. n2 concentration will decrease. b. n2 concentration will not change. c. n2 concentration will increase. d. n2 concentration will not change, but δh will decrease. e. n2 concentration will not change, but pressure will increase.

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Answer from: giulissaf

18. Answer is A

Since the enthalpy of reaction is positive, the forward reaction is an endothermic reaction which means the energy is gained from the surrounding to happen the reaction. If the temperature decreases, according to the Le Chatelier's principle, the system tries to become equilibrium by increasing temperature. Since forward reaction is endothermic (because of the bond breaking), the backward reaction is exothermic (because of the bond making) which releases the energy to the surroundings. This makes the increase of temperature. So if the backward reaction is promoted because of the decrease of temperature, then the concentration of H₂ will decrease.

19. Answer is A.

The reactant side has 2 moles/molecules of reactants and the product side has 4 moles/molecules of products which come from 1 N₂(g) and 3 H₂(g). If the pressure is reduced in the system, according to the Le Chatelier's principle, the system tries to increase the pressure. Hence, forward reaction is promoted because of the higher number of molecules in product side. If the forward reaction is promoted, the concentration of NH₃(g) will decreased.

20. Answer is C.

If the concentration of reactant is increased in the system, according to the Le Chatelier's principle, the system tries to reduce the concentration of that reactant. So if NH₃(g) concentration is increased, then to be equilibrium, the forward reaction will be promoted. Then the concentration of N₂(g) will increase.

Answer from: Quest

dynamic equilibrium is the answer.

Answer from: Quest

The answer to your question really depends on three things: how much water you have, how cold it is to start out, and how cold the things around it are. water actually freezes when it gets to 32 degrees fahrenheit (0 degrees celsius), but the time it takes to get there may be different. let's start with the first. if you take two glasses, and fill one with a tiny bit of water, and the other about halfway, then put them both in the freezer, the one with less water will freeze first (you can try this at home, but i recommend using plastic cups and not glass ones). now let's move on to the second part. let's say you have two glasses, and you fill one with really cold water that has been in the refrigerator, and the other with really hot water from the sink. if you put both of them in the freezer, the one that started out colder will freeze first. for the third part, let's imagine that you have two glasses with the same amount of water in them, and the water is at the same temperature. imagine putting one outside on a really really cold day in georgia, and having a friend in alaska put one outside on the same day. since it would be so much colder in alaska, the glass of water there would freeze before yours. so, if you took a tiny bit of really cold water in a glass, and put it outside on a cold day in alaska, it would freeze a lot faster than a big glass of hot water outside on a cold day in georgia.

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Questions 18-20 refer to the reaction 2nh3 (g) ↔ n2 (g) + 3h2 (g), and δh = 92.2 kj. what will be t...

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