# Molarity Question

#### Rocket52

Hello everyone,
It's my first time on here and I have a question to ask.
0.30 moles magnesium nitrate is weighed out and then dissolved in water to an exact volume of 500mL. Which of the following is correct?
A. the concentration of nitrate ions is 0.30mol/L
B. the concentration of magnesium ions is 0.10mol/L
C. the concentration of nitrate ions is 1.2mol/L
D. the concentration of magnesium nitrates is 0.3mol/L

So what I've done is calculate the molarity of magnesium nitrate which is 0.6mol/L (using c=n/v). What do I have to do next?

#### studiot

What is the chemical formula for magnesium nitrate ?

How many moles of nitrate ion are there per mole of magnesium nitrate?

Using this formula, if (as you have correctly calculated) the concentration of magnesium nitrate is 0.6 moles/L , how many moles/L of nitrate ion are there?