CHEM HELP???? please answer with as much detail as possible!!!?

Question

Numeric Response

25. If the hydronium ion concentration is 10M, what is the pH of the solution?

26. If [OH] = 1 10M, what is the pH of the solution?

27. What is the pH of a solution with a concentration of 0.01M hydrochloric acid?

Short Answer

28. Use the information below to calculate ΔH for the following reaction: 2NO(g) NO(g)

N(g) + 2O(g) 2NO(g) ΔH = 67.7 kJ
N(g) + 2O(g) NO(g) ΔH = 9.7 kJ

29. What is the hydronium ion concentration if the pH is 3.7?

30. What is the pH if the hydronium ion concentration is 6.8 10M?

Problem

31. How much heat is absorbed by 15.5 g of water when its temperature is increased from 20.0°C to 50.0°C?

32. How much energy is released when 500g of water vapor at 1000C condenses to form liquid water at the same temperature?

Answer 1

I normally wouldn't condone answering these questions (they're clearly from a homework assignment), but as it is a new year and I have a few minutes....

25. pH = - log[H+] where [H+] is the concentration of hydrogen ions (or, as you listed, hydronium ion; they're interchangeable in pH questions). So, pH = -log10 = -1 (Answer = -1)

26. I think you may have typoed here, maybe it's [OH] = 10M? At any rate, if [OH] = 10M, pOH = -log[OH-], so pOH = -log10 = -1. pH + pOH = 14, so pH = 14 - pOH = 14 - (-1) = 15 (answer: pH = 15)

27. A solution with .01M HCl has a hydrogen concentration of .01M, so pH = -log(.01) = 2 (answer: pH = 2)

28. delta H (dH) of 2NO(g) -> NO(g) can be given by reversing the first equation and then adding the two equations together. So, we change the sign of dH for the first equation then add the two values: -67.7kJ + 9.7 kJ = -58kJ (answer: dH = -58 kJ)

29. pH = -log[H+]
pH = 3.7
10^(-3.7) = [H+] = 1.995 x 10 ^ (-4) = 0.0001995

30. I don't follow what the concentration is, but you'd simply plug in the concentration as such:
pH = -log[H+] where [H+] is the concentration of the hydronium ions. Just plug in the value for [H+] into the equation.

31. q = mcdT (dT = change in temperature, always final minus initial). m = 15.5g, c for water is 4.184 J/g * C (Joules per grams time degrees (Celsius)), and dT is 50 - 20 = 30 degrees C.
q = (15.5)(4.184)(30) = +1950J (Answer)

32. Only question here that I don't know for sure, but my best guess is that no net energy is released since this is a thermodynamic phase change with no change in temperature.

Good luck!

Answer 2

im particular in case you inform you'r uncles they may be slightly disgusted yet they're going to recover from it i wudnt difficulty bout tht! No it doesnt harm in any respect i think of it definitely relies upon on wether you get it numbed like i did even even though it purely looks like some one is pulling at ur abdomen thats it. and all u want 2 do 2 save it sparkling it have some heat salt water and a cotten bud and sparkling it. In wellbeing midsection type in the event that they no u have it finished they might ask u 2 hide it with a plaster so it doesnt get caught on something yet good success with it

Answer 3

25. pH = -Log[H+]

[H+] = 10; Log10 = 1; -Log10 = -1, a meaningless number, because pH is used only for very dilute solutions.

26. Kw = [H+][OH-] = 10^-14

[H+](10) = 10^-14

[H+] = 10^-15

pH = 15 also a meaningless number. Once you get to 10M acid or 10M base, the liquid no longer resembles water. In these solutions, pH = -Log(a), where a is the activity of the [H+]. To know that,you have to multiply [H+] by the activity coefficient.

27. [H+] = 0.01; Log(0.01) = -2; pH = 2

28. You copied the problem wrong

29. pH = 3.7; so Log[H+] = -3.7 = -4 + 3; then [H+] = 2 x 10^-4

30. I assume you mean that [H+] = 6.8 x 10^-10

(6.8x10^-10)[OH] = 10^-14

[OH-] = 1.5 x 10^-5; pOH = 5; pH = 9

31. 50.0C - 20.0C = 30degC difference. 15.5gH2O x 30degC x 1cal/deg-g = 465 cal

32. It is impossible for water to condense from steam to water at 1000C. That temperature is far above the critical temperature of water, above which water cannot be condensed to liquid no matter how great the pressure. I suspect that you want to know the energy released when steam is cooled from 1000C to100C and then condensed to water at the same temperature. For that, you would have to have the heat capacity of steam and the latent heat of vaporization of water.

Answer 4

i think this will help you let me know