×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

#### Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

# Mixing different gasses3

## Mixing different gasses

(OP)
How can I calculate the mass of ISO-Butane vapour that will saturate 1kg of ammonia vapour at the same temperature?

### RE: Mixing different gasses

3
First you have to define your conditions. You cannot saturate with isobutane unless isobutane is a liquid under the conditions of interest. Here is a link to a vapor pressure graph for isobutane (http://encyclopedia.airliquide.com/images_encyclop...). If your conditions are below the curve or above the critical temperature of isobutane there can be no liquid phase present and ammonia and isobutane will be completely miscible at all concentrations. This assumes that you are under conditions that ammonia is not a liquid. Here is a link to a vapor pressure graph for ammonia (http://encyclopedia.airliquide.com/images_encyclop...). For ammonia to be a gas your conditions must be below the curve or above the critical temperature of ammonia. Assuming you are under conditions where ammonia is a vapor and isobutane can be a liquid, read off the vapor pressure for isobutane to get the partial pressure of isobutene. Subtract this from the total pressure to get the vapor pressure of ammonia. Assuming the ideal gas law and that ammonia is negligibly soluble in isobutane (both questionable assumptions), the ratio of moles of isobutane to moles of ammonia is equal to the partial pressure ratio. From the mole ratio you can calculate the mass ratio. If you need a better number you will need measured solubility of ammonia in isobutane and use real gas models for both. Your easiest option would be to enlist the aid of someone who has access to Aspen Plus (and knows what they are doing) and have them do your calculation.

### RE: Mixing different gasses

lloydbrown.
Hope you will stay for long in this website so we can learn from you more often.

### RE: Mixing different gasses

(OP)
lloydbrown.
I haven't had time to research your info at this stage but like rotaryworld I hope you stay around. Thank you

#### Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

#### Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!