Achieve Hw 2, 3, 4, Question 17

[605988349]

Hi,

For this question, I don't know where I'm going wrong with my calculations.

"The average speed of a diatomic molecule at 25C is 323.9m.s^-1. What is the average wavelength of a chlorine molecule at this temperature? Assume that the molecule acts as a single particle."

First I found the mass of Cl which is 35.453g. But, since it's diatomic I multiplied that by two which equals to 70.906. I think did divided that with Avogadro's constant: 70.906/6.02214x10^23 = 1.177x10^24g. Which converting that into kg it would be 1.177x10^21kg.

Now the formula would be lambda= h/mv

lambda= (6.626*10^-34)/((1.177*10^21)(323.9) = 1.738*10^-57. However, it shows as incorrect in Achieve.

Can anyone explained in steps where I messed up?

Thank you.

[Christian_Lee_2K]

Hi there!

I believe that there is an error in the Cl mass because I found that the diatomic Cl molecule's mass is 1.177449352*10^22. Then, I multiplied by 10^-3 because 1 g = 10^-3kg. Therefore, I got 1.177449352*10^25 kg.

I hope this helps!

[Ishita S 2E]

If I'm not wrong, I believe where you went wrong is finding the correct mass. 70.906 divided by (6.022*10^23) should be 1.1744*10^-22 g, then converted into kg is 1.1744*10^-25. Maybe when putting it into the calculator you forgot to put parentheses around 6.022*10^23.

[Hao Tam Tran 3H]

Hi!

Well, first, it appears you did the calculation wrong for the mass of Cl because when you calculate 70.906/(6.02214x10^23), you get 1.177 x 10^-22 g, or 1.177 x 10^-25 kg. You might have just forgotten a parentheses around the denominator. Thus, your wavelength would be lambda=(6.626*10^-34)/((1.177*10^-25)(323.9)) = 1.74 x 10^-11 m.