Nyhetsflöde

Problem 12: Who said you need to use everything that is given in the problem? I often give more data than is needed, it's a part of the problem to understand what to use and what not to use.

Problem 11: The exercises are taken from the 'old' Nuclear Chemistry course. The radiation chemistry questions are not included in this course (13 & 16 and half 11), so you don't have to bother about these. The thing you should be able to calculate is the dose rate.

(and to answer your question: First calculate the dose rate, then use the G-value given in problem 16 to obtain the H2O2-concentration. Plug the concentration into the the given equation and you will get the rate of oxidation. And no, oxidation rate is not the same as dose rate)

Thank you :)

I guess you are referring to one of the problems in the exercises. I realize that the expression that should have been used in the problem is 'the efficiency of the isotope exchange' or maybe even better, 'complete isotope exchange was achieved and the ratio between tritium and hydrogen at the acidic positions were 1.7:1'

When using radiotracers, complete isotope exchange is important (Lecture 5). Complete isotope exchange means that the ratio between non-radioactive element and radioactive isotope of the same element is the same everywhere in the system.

An isotope exchange efficiency would be a measure of how efficient the isotope exchange would be. That would mean that a part of the non-radioactive elemets would not be irreversibly excluded from interacting with the rest of the system or that the system isn't in equilibrium. In the example we are referring to this would mean that you don't have sufficient information to solve the problem (you don't know how the ratio tritium/'acidic hydrogen').

Which problems are you referring to?

ALL isotopes of the actinides are radioactive. However, Th-232, U-235 and U-238 have very long half-lives, so they still occur naturally (U-234 also occurs naturally, but that is only since it is in the decay chain of U-238).

Actinides are the group furthest down in the periodic table, including the elements Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No and Lr, see lecture 6.

Lead is the heaviest element with stable isotopes. Sometimes Bi is considered to be the heaviest element with stable isotopes, since Bi-209 has a half-life of 2*10^19 years (="almost stable").

Hi Helen,

Old exams can now be found at the home page http://www.kth.se/che/utbildning/kurswebbar/KD2430/VT11-1/2.28448/old-exams-in-nuclear-chemistry-1.80332

Good. I'll prepare to show how to solve them.

Any other problem we shall take on the white board? Anyone?

It's the abundance (the number 4.35 under "Cr50"). Natural Cr is 4.35% Cr50, 83.79% Cr52, 9.5% Cr53 and 2.36% Cr54.

ok thanks

kolla din mail

/mats

Yes, they will.

I'm at Lanzarote this week :D and I forgot to give Susanna the priveleges to make changes at the home page. This week's lectures will be up at latest Tuesday next week

The answers are now up on the home page, look under activities.

I have added some reading directions, see schedule in the right column of the starting page. I am not sure what material Susanna will use.