Given a 1*L volume of solution that is 1.25*mol*L^-1 with respect to MgCl_2, there are...? "a. 2 moles of ions in solution." "b. 1.25 moles of ions in solution." "c. 2.5 moles of ions in solution." "d. 2 moles of ions in solution."

Given a 1*L volume of solution that is 1.25*mol*L^-1 with respect to MgCl_2, there are...
"a. 2 moles of ions in solution."
"b. 1.25 moles of ions in solution."
"c. 2.5 moles of ions in solution."
"d. 2 moles of ions in solution."

1 Answer
anor277
May 3, 2017

"Option c............"

Explanation:

The "mole", N_A, is simply a number. Admittedly, it is a very large number, N_A=6.022xx10^23*mol^-1.

And if you have a mole of stuff, you have 6.022xx10^23 INDIVIDUAL ITEMS of that stuff. Here you have a concentration of 1.25*mol*L^-1 MgCl_2. In 1*L of solution there are 1.25*mol Mg^(2+) ions, BUT ALSO 2xx1.25*mol Cl^- ions.....

And thus in total you have 2.5xxN_A Cl^- per litre of this solution. This is a basic, underlying principle of chemistry, and if you can develop this idea of chemical equivalence, where MASS and CONCENTRATION corresponds to numbers of molecules and atoms, you will save yourself a lot of trouble,

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