Understanding Limiting Reagents and Pressure Calculations in Gas Reactions

In summary, in a reaction between NH3(g) and HCl(g), NH4Cl(s) is formed. The limiting reagent is HCl and the final pressure in the apparatus can be calculated using the ideal gas law. However, an additional step is needed where the moles of both gases are subtracted before using the gas law. The volume of NH4Cl(s) is negligible and does not have to be considered in the calculation. Good luck on your test!
  • #1
Lancelot59
646
1
NH3(g) + HCl(g) --> NH4Cl(s)

A 2.00 L flask containing 5.00 g of NH3 is connected to a 2.00 L flask containing 5.00 g of HCl. When the stopcock between the two flasks is opened the gases react until one of them is completely consumed. What is the final pressure in the apparatus when the reaction is complete? The temperature of the system is 25oC.

Well I found that HCl was the limiting reagent. I figured that since the equation is a 1:1 ratio I could just set the mols of NH4Cl as the mols of HCl and solve for the pressure using the ideal gas law.

Apparently there is another step, where I have to subract the mols of the two gasses, and then use THAT value in the gas law.

What is going on here? How is that value the number of mols in the NH4Cl?
 
Physics news on Phys.org
  • #2
NH4Cl(s). Its volume is so small that it doesn't count.

--
 
  • #3
I see now. Thanks. Wish me luck on the test today.

I really should've studied more. My other courses drove this test out of my head entirely.
Dumbass powers activate!
 

1. What is the best way to prepare for an exam?

The best way to prepare for an exam is to start early and create a study schedule. Make sure to review class materials and notes regularly, and practice with past exams or study guides. It is also important to get enough rest and eat well before the exam.

2. How can I manage my time effectively during an exam?

To manage your time effectively during an exam, make sure to read all instructions carefully and budget your time accordingly. Start with the easier questions and save more time for the harder ones. Don't spend too much time on one question, and make sure to leave some time at the end to review your answers.

3. What should I do if I don't know the answer to a question on the exam?

If you don't know the answer to a question on the exam, don't panic. First, try to eliminate any obviously incorrect answers. If you still don't know the answer, move on to the next question and come back to it later if you have time. If you are still unsure, make an educated guess based on your knowledge and the information given in the question.

4. How can I stay calm and focused during an exam?

To stay calm and focused during an exam, take deep breaths and remind yourself that you have prepared for this. Don't get too hung up on one question and try to stay positive. If you find yourself getting anxious, take a short break to stretch or close your eyes and refocus.

5. What can I do to improve my study habits for future exams?

To improve your study habits for future exams, reflect on what worked well and what didn't for this exam. Make adjustments to your study schedule and techniques accordingly. You can also seek advice from your teachers or classmates on effective study methods. Don't forget to take care of your physical and mental health as well, as this can greatly impact your academic performance.

Similar threads

  • Biology and Chemistry Homework Help
Replies
16
Views
2K
  • Biology and Chemistry Homework Help
Replies
10
Views
4K
  • Biology and Chemistry Homework Help
Replies
5
Views
1K
  • Biology and Chemistry Homework Help
Replies
3
Views
41K
  • Biology and Chemistry Homework Help
Replies
8
Views
5K
  • Biology and Chemistry Homework Help
Replies
16
Views
2K
  • Biology and Chemistry Homework Help
Replies
2
Views
3K
  • Biology and Chemistry Homework Help
Replies
2
Views
4K
  • Biology and Chemistry Homework Help
Replies
1
Views
2K
  • Biology and Chemistry Homework Help
Replies
4
Views
5K
Back
Top