text: ## Uncertainty in Speed [ENDORSED]
  
  $\Delta p \Delta x\geq \frac{h}{4\pi }$
  
  Veronica_Lubera_2A
  Posts: 106
  Joined: Sat Sep 14, 2019 12:16 am
  Been upvoted: 1 time
  
  ### Uncertainty in Speed
  
  The hydrogen atom has a radius of approximately 0.05 nm. Assume that we know the position of an electron to an accuracy of 1% of the hydrogen radius, calculate the uncertainty in the speed of the electron using the Heisenberg uncertainty principle.
  
  So the correct answer is Delta V >= 10^8 m/s. How would you solve the question to receive this answer?
  
  Chem_Mod
  Posts: 18890
  Joined: Thu Aug 04, 2011 1:53 pm
  Has upvoted: 716 times
  
  ### Re: Uncertainty in Speed  [ENDORSED]
  
  I will be covering this topic in class during Week 2.
  
  Calculate 1% of the hydrogen radius (0.05 nm) in meters and use it as the uncertainty in position, delta x, of the electron in the Heisenberg Indeterminacy (Uncertainty) Equation.
  
  Sears 4A
  Posts: 36
  Joined: Tue Feb 05, 2019 12:15 am
  
  ### Re: Uncertainty in Speed
  
  I do not think we are covering this until week 2, and the week 2 homework can be from review or quantum, so maybe wait until Dr. Lavelle goes over this in lecture!
  
  AnayaArnold_3L
  Posts: 56
  Joined: Wed Sep 18, 2019 12:19 am
  
  ### Re: Uncertainty in Speed
  
  Veronica_Lubera_1A wrote:The hydrogen atom has a radius of approximately 0.05 nm. Assume that we know the position of an electron to an accuracy of 1% of the hydrogen radius, calculate the uncertainty in the speed of the electron using the Heisenberg uncertainty principle.
  
  So the correct answer is Delta V >= 10^8 m/s. How would you solve the question to receive this answer?
  
  Dr.Lavelle will more than likely go over this concept more in a lecture during week 2 so I wouldn't worry about it too much as of right now.
  
  KatherineValdez_4B
  Posts: 22
  Joined: Sat Sep 14, 2019 12:17 am
  
  ### Re: Uncertainty in Speed
  
  I really hope he does cover it because I'm confused.
  
  andrewcj 2C
  Posts: 102
  Joined: Thu Jul 11, 2019 12:17 am
  
  ### Re: Uncertainty in Speed
  
  I think it goes like this:
  ($\Delta$p)($\Delta$x) = (1/2)(h/2$\pi$)
  ($\Delta$p) = m($\Delta$v)
  From here you can plug in (0.01)*(0.05 nm) for $\Delta$x and solve.
  
  andrewcj 2C
  Posts: 102
  Joined: Thu Jul 11, 2019 12:17 am
  
  ### Re: Uncertainty in Speed
  
  One additional thing for my reply, make sure you convert nm to m.
  
  nicole-2B
  Posts: 103
  Joined: Fri Aug 30, 2019 12:18 am
  
  ### Re: Uncertainty in Speed
  
  andrewcj 4I wrote:One additional thing for my reply, make sure you convert nm to m.
  
  thanks for clarifying this.
  
  melinak1
  Posts: 25
  Joined: Tue Sep 24, 2019 12:17 am
  
  ### Re: Uncertainty in Speed
  
  andrewcj 4I wrote:One additional thing for my reply, make sure you convert nm to m.
  
  ohh ok thank you!
  
  KatherineValdez_4B
  Posts: 22
  Joined: Sat Sep 14, 2019 12:17 am
  
  ### Re: Uncertainty in Speed
  
  andrewcj 4I wrote:One additional thing for my reply, make sure you convert nm to m.
  
  Thanks for this I almost forgot to do it.
  
  Aprice_1J
  Posts: 55
  Joined: Wed Sep 18, 2019 12:16 am
  
  ### Re: Uncertainty in Speed
  
  Another important conceptual thing to think about is that the more you know about the position of an electron, the less we know about its velocity- they have an inverse relationship.
  
  Anvi Brahmbhatt 4A
  Posts: 51
  Joined: Wed Sep 18, 2019 12:21 am
  
  ### Re: Uncertainty in Speed
  
  andrewcj 4I wrote:I think it goes like this:
  ($\Delta$p)($\Delta$x) = (1/2)(h/2$\pi$)
  ($\Delta$p) = m($\Delta$v)
  From here you can plug in (0.01)*(0.05 nm) for $\Delta$x and solve.
  
  Thank you for the explanation!
  
  Claire Stoecklein 1E
  Posts: 49
  Joined: Sat Jul 20, 2019 12:15 am
  
  ### Re: Uncertainty in Speed
  
  When you determine delta p for the indeterminacy equation, make sure to use p=mv, using the velocity given in the equation and the mass of electron, 9.109 x 10^-31.
  
  brennayoung
  Posts: 51
  Joined: Fri Sep 20, 2019 12:17 am
  
  ### Re: Uncertainty in Speed
  
  This equation can be used for other atoms than hydrogen right?
  
  Ruth Glauber 1C
  Posts: 100
  Joined: Wed Sep 18, 2019 12:20 am
  
  ### Re: Uncertainty in Speed
  
  I think you need to calculate 1% of the hydrogen radius (0.05 nm) in meters for the uncertainty.
  
  Caitlin Ciardelli 3E
  Posts: 44
  Joined: Wed Sep 18, 2019 12:19 am
  
  ### Re: Uncertainty in Speed
  
  Another way to calc uncertainty in v:
  
  10 ms^-1 +/- .5
  You can take the +/- value and multiply it by 2. This is another way to find uncertainty in v
  
  Posts: 102
  Joined: Wed Sep 18, 2019 12:18 am
  
  ### Re: Uncertainty in Speed
  
  In response to Brennayoung's question, I believe that we will only be applying this to hydrogen for now. This principle is used when measuring position and momentum of a particle.
  
  Sara Richmond 2K
  Posts: 110
  Joined: Fri Aug 30, 2019 12:16 am
  
  ### Re: Uncertainty in Speed
  
  Use these equations:
  (delta p)(delta x) = (1/2)(h/4 PIE)
  (deltap) = m( delta v)
  
  Sometimes this type of problem can be confusing because they dont give you the delta p equation.
  
  Also remember to multiply the delta v uncertainty by 2 because it is plus or minus a certain amount.
  
  Mitchell Koss 4G
  Posts: 128
  Joined: Sat Jul 20, 2019 12:17 am
  
  ### Re: Uncertainty in Speed
  
  Also, don’t confuse frequency (v) with velocity (v)
  
  Jack_Pearce_2F
  Posts: 41
  Joined: Wed Sep 30, 2020 9:48 pm
  
  ### Re: Uncertainty in Speed
  
  you would use the heisenberg uncertainty equations to solve this but more likely than not the result would be very off because the electron is known to a very close degree of certainty