Question 40

[dwumi1604]

Re: A sharp increase in the ammeter reading was observed when the voltage was 22V. What is the ionization energy in terms of eV/mol?

Can someone



Can someone please explain how/why we multiply and divide 1.6 E-19...im a little confused with the explanation provided.


Thanks

[mcat_premed3832]

This problem requires no previous knowledge other than an understanding of dimensional analysis (if you don't have the GS book, then read here: www.alysion.org/dimensional/fun.htm).

Using DA is common on the new MCAT: you must focus on the units of everything you are provided and then look at the units of the answer that you must get. Then you multiply, add, divide or whatever by carefully following the units.

All necessary values are given at the end of the passage.

[thaertlein2125]

wouldnt this add up to
"1.32 x 1025 (eV x electrons)/mole"
since there is nothing to cancel out the electrons

does it not matter that there is an extra variable?
Or, should it be read as 1.6 x 10-19 C/electron or something like that.

I know it's semantics, but im curious.

[mcat_premed3832]

Yes, from a dimensional analysis point of view, because the charge on a single electron is 1.6 x 10-19 C, one can write:

1.6 x 10-19 C/electron