What is the number of moles of solute in 250 ml of a 0.4 m solution? don't forget the unit.

Using the equation we get something like this:

M = moles of solute/ liters of solution

But we need the number of moles of solute right? so we gotta arrange the equation to make it fit our needs.

M x liters of solution = moles of solute

M = mol/L

Liters of solution = L

moles of solute = mol

We have the M which stands for the molar mass in mol/L (0.4M)

And we also have the mL which are the liters of our solution, yet to be converted into liters. Let's divide them by a 1000 to make it into liters.

250mL / 1000 = 0.250L

Now we can multiply them! and find the number of moles of solute by replacing them, remember M can be changed into m/mol, because it's pretty much the same but written in another way.

0.4mol/L x 0.250L = 0.1 mol

The liters canceled, and we end up with mol. So, the answer is 0.1 mol.