Given a 1L volume of solution that is 1.25molL1 with respect to MgCl2, 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 1L volume of solution that is 1.25molL1 with respect to MgCl2, 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
May 3, 2017

Option c............

Explanation:

The mole, NA, is simply a number. Admittedly, it is a very large number, NA=6.022×1023mol1.

And if you have a mole of stuff, you have 6.022×1023 INDIVIDUAL ITEMS of that stuff. Here you have a concentration of 1.25molL1 MgCl2. In 1L of solution there are 1.25mol Mg2+ ions, BUT ALSO 2×1.25mol Cl ions.....

And thus in total you have 2.5×NA 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,