December 01, 2021, 01:52:58 AM
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Topic: EMERGENCY - Volume Question I've been stuck on!  (Read 277 times)

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Offline NS220

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EMERGENCY - Volume Question I've been stuck on!
« on: October 25, 2021, 12:03:09 AM »
Course: Inorganic Chemistry 1 (College level)

Can someone please help me solve this question?? I have been stuck on it for over an hour and need the answer in the next 8 hours!!

How many liters of H2 can be produced when 0.5g of Aluminum reacts with HCl if the atmosphere pressure is 730 mm Hg, the temperature 25'C, and the vapor pressure of water at that temperature is 24 mm Hg?

2 Al + 6 HCl --> 2 AlCl3 + 3 H2

a) 0.056

b) 1.27

c) 0.5

d) 0.64

My solving process was this:

PV = nRT
V = nRT/P

P = 730 mm Hg / 760 mm Hg
   = 0.96 atm

K = 25'C + 273
   = 298

Al = 27g
H = 1g
Cl = 35.45g

g H = (0.5g Al) (6g H / 54g Al)
      = 0.0555 g

n = (0.0555g H) (3 moles / 6g H)
   = 0.02775

So V = (0.02775) (0.0821 L-atm/k-mol) (298 K)  /  0.96 atm
        = 0.707 L

But this doesn't fit in the formula because the answer I get is not in the options I have to choose from.

Can someone please tell me what I am doing wrong and guide me in the right direction on how I would solve something like this from the information given in the question?

PLEASE SHOW HOW YOU GOT THE ANSWER SO I CAN UNDERSTAND HOW TO CALCULATE SIMILAR PROBLEMS.

Thank you!

Offline Borek

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Re: EMERGENCY - Volume Question I've been stuck on!
« Reply #1 on: October 25, 2021, 03:16:16 AM »
Your answer is more or less correct (I got 0.708 L), there is no correct answer to choose from.

Plus, the question is either poorly worded or tries to be tricky. It gives vapor pressure as if it expected you to find "what volume of gas was collected", yet it asks about the volume of H2 produced. Collected and produced are not synonymous here.
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