Chemistry Question?

Question

I hope someone can show me how to work out these problems step by step. I am having trouble with my chemistry homework.
The quetions are:

At 3.00 m from a radioactive source the intensity of its gamma radiation is 202 roentgen. How far away would we need to be to reduce the intensity to 4.64 roentgen.

At 2.00 m from a radioactive source the intensity of its gamma radiation is 522 roentgen. What is the intensity at a distance of 37.8 m?

I would appreciate any help.

Answer 1

I am an irradiator operator at a big company and I solve these all the time. Here goes: You will be using the inverse square law
(Initial Intensity)(Initial Distance)^2= (Final Intensity)(Final Distance)^2

Initial Intensity=202 R Final Intensity= 4.64
Inital Distance= 3.00 m Final Distance = unknown

(202)(3)(3)=(4.64)(unknown)^2
1818=(4.64)(unknown)^2
1818/4.64 = unknown^2
391.8= unknown^2
square root 391.8 = unknown
Final Distance: 19.79 m

Second problem:

Initial Intensity = 522 R Final Intensity = Unknown
Initial Distance = 2.00 m Final Distance = 37.8

(522) (2)(2) = (37.8)(37.8)(unknown)
2088/1428.84 = unknown
1.46 R = Final Intensity

Hope this helps. I also have a BS in Chemistry

Answer 2

This question involves the inverse square law. at 1 m intensity =1/1^2 at 2 m Intensity = 1/2^2 at 3 m intensity = 1/3^2 etc.

What you need to find is the distance at which the intensity is 4.64 roentgen. Or : 4.64 = 202/d^2 where "d" is the distance away from the source. Same equation with second problem, just switch variables.

Answer 3

Figure out the unit rate for the roentgen and then figure it to answer 4.64. Same with the second. Figure the unit rate and set equation to work. Also works as a proportion.

Answer 4

This is a question about the inverse-square law (radiation intensity decreases with the inverse square of the distance from the source). Read all about it here:

http://en.wikipedia.org/wiki/Inverse-square_law

Answer 5

what's a roentgen?

Answer 6

Is that chemistry or physics?