Uranium-235 can be separated from U-238 by fluorinating the uranium to form UF6 (which is a gas) and then taking advantage of the different rates of effusion and diffusion for compounds containing the two isotopes.

Calculate the ratio of effusion rates for 238UF6 and 235UF6 The atomic mass of U-235 is 235.054amu and that of U-238 is 238.051amu.

What steps do I take to answer this question?

rates of effusion are inversely proportional to the sqrt of atomic masses.

Rate235/rate238= sqrt (238.05/235.054)

1.0056

But isnt the equation for rate of diffusion sqrt(MB/MA) so it would be sqrt(238/235)

To answer this question, you need to use the concept of Graham's law of effusion, which states that the rate of effusion (or diffusion) of a gas is inversely proportional to the square root of its molar mass.

Step 1: Determine the molar masses of both compounds.
The molar mass of 238UF6 can be calculated by adding the molar mass of U-238 (238.051 amu) to the molar mass of six fluorine atoms (6 x 18.998 amu, since fluorine has an atomic mass of approximately 18.998 amu). Similarly, for 235UF6, you'll add the molar mass of U-235 (235.054 amu) to six fluorine atoms.

Step 2: Calculate the square roots of the molar masses.
Take the square root of the molar mass of 238UF6 and the square root of the molar mass of 235UF6. This will give you the square root of the molar masses for each compound.

Step 3: Calculate the ratio of effusion rates.
The ratio of effusion rates is determined by dividing the square root of the molar mass of the first compound by the square root of the molar mass of the second compound. In this case, you divide the square root of the molar mass of 238UF6 by the square root of the molar mass of 235UF6 to get the ratio.

Step 4: Simplify the ratio.
Once you have the ratio of effusion rates, simplify it if possible.

By following these steps, you should be able to calculate the ratio of effusion rates for 238UF6 and 235UF6.