1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

How do you calculate kpa/min?

  1. Jan 8, 2012 #1
    How do you calculate kpa/min??

    1. I am trying to find the rate of CO2 production in yeast fermentation. I used a gas pressure sensor to measure the kpa every minute. I recorded the initial kpa and the kpa after every minute for four minutes. I forgot how to calculate the kpa/min and need clarification



    2. I think the equation is something like this:
    Initial pressure - final pressure/ (seconds?) I doubt this is right



    3. For instance, the initial pressure was 99.05 kpa and after a minute it was 99.03.
    So would the rate be -.02 kPa/min?
    Can someone please help or steer me in the right direction?
    Any help would be appreciated.
     
    Last edited by a moderator: Jan 9, 2012
  2. jcsd
  3. Jan 8, 2012 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Re: How do you calculate kPa/minute? Pleaaase help!

    You plot a graph of pressure vs time and find the slope
    (you have more than one data point so you may as well use them)

    Quick-and-dirty method, take the difference between final and initial pressure readings, divide by 4mins.

    Yes - do you need to worry about uncertainty? Best to take values farthest apart: it's change in pressure divided by change in time.
    Measure changes in the units you need - so if you want kPa/min, measure pressure in kPa and time in mins ... if you need psi/decade, then...
     
  4. Jan 9, 2012 #3

    Borek

    User Avatar

    Staff: Mentor

    Re: How so you calculate kpa/min??

    Yes, that's the average rate of the pressure change for the first minute.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook