A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • one year ago

Calculate the average atomic mass of rubidium. Rubidium has two isotopes, 85^Rb and 87^Rb. 85^Rb has an atomic mass of 84.912 amu and occurs at an abundance of 72.17%. 87^Rb has an atomic mass of 86.909 amu and occurs at an abundance of 27.83%. Show your work.

  • This Question is Open
  1. Frostbite
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    To try calculate the atomic masses of our molecules we define calculate the relative (average) atomic masses. The relative/average comes from the idea that we weight the masses with their probability of occurrence. In terms of math: \[\large M_{element}=\sum_i m_i \times p_i\] Here is \(m_i\) the mass of the \(i\)'th isotope with the probability of occurrence \(p_i\). If the math confuses you, I can show you more specifically how to apply this for rubidium.

  2. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Yeah if you don't mind showing the math to me that would be really helpful

  3. Frostbite
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Basically the function just say we must add up these "weighted masses" So: \[\large M_{ribidium}=m(^{85}\text{Rb}) \times p(^{85}\text{Rb}) +m(^{87}\text{Rb}) \times p(^{87}\text{Rb})\] From here it is all about plugging in numbers, just remember to make your percentages into decimal numbers.

  4. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Thank you so much for your help! :)

  5. Frostbite
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    No problem at all. If you want to write out your answer I can check it for you before you turn it in.

  6. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.