×
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.

# Help with calculating the headspace concentration of butyric acid in a 1 mM

## Help with calculating the headspace concentration of butyric acid in a 1 mM

(OP)
Hi everyone,

I´m stucked with a very easy chemistry problem. I have a 10ml crimped vial with 2ml of a 10 mM solution of butyric acid, the headspace volume is 8 ml. Our company is developing a sensor and we need to know the concentration of butyric acid in the headspace of the closed vial.

I´ve tried to make the calculation with the following formula:

n=Pg x Vh/R x T

Where Pg is the partial pressure of butyric acid in the headspace and Vh is the volume of the headspace.

I obtained Pg from the following formula: Pg=Ca/Kh, where Ca is the concentration of butyric acid in aqueous solution and Kh is the henry´s law constant for butyric acid (1900 M/atm).

n= (2.63x10-5)x(0.008L)/0.08205 atm L mol-1 K-1 x 293 K
n=8.75x10-9 mol

To get the concentration in the headspace I divide the mols I obtained above by the headspace volume (0.008L). I get a headspace concentration of 0.00109mM.

This seems extremely low to me, and I have the feeling that there is a mistake in the way I´m making the calculations, but I can´t put my finger on it.

I would really appreciate if somebody out there could give me a hand with this. Thanks so much in advance.

#### 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.

#### Resources

eBook - Manufacturing the Cars of Tomorrow
In this ebook, we'll explore how additive manufacturing is going to transform the way cars are made. This includes commentary from thought leaders such as Ford's CTO, Ken Washington, Customer case studies of ways 3D printing is being used today, and a variety of part examples where 3D printing is already impacting how automobiles are made. Download Now
White Paper - Smart Manufacturing for Semiconductor
New technologies and approaches present great opportunities for semiconductor manufacturers to achieve high levels of innovation, yield and improvement. This white paper explores some of these cutting-edge technologies and how they can be applied effectively in the semiconductor industry. Read about how Smart Manufacturing is transforming the semiconductor industry. Download Now
White Paper - Analysis and Simulation in Aircraft Structure Certification
Organizations using simulation and analysis tools effectively see the benefits in their ability to achieve certification faster and with drastically less total cost than those who do not maximize these tools. Read this White Paper to learn about how digital tools such as analysis and simulation help in aircraft structure certification. Download Now

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!