Question

You want to analyze a cadmium nitrate solution. what mass of naoh is needed to precipitate the cd2+ ions from 32.7 ml of 0.499 m cd(no3)2 solution?

Answer 1

First, we must know that in order to remove one mole of cadmium ions, we will require two moles of sodium ions. This is visible from the fact that the valence charge of cadmium ions is +2, while for sodium ions it is +1.

Next, we use the equation:

Moles = Molarity * Liters

We know that:

moles of sodium =  2 * moles of cadmium

Now, the moles of cadmium present are:
Moles = 0.499 * 0.0327 = 0.0163

The moles of NaOH required are double this, so:

Moles NaOH = 2 * 0.0163 = 0.0326

Mass = moles * molecular weight

Mass  = 0.0326 * 40
Mass = 1.304 grams of NaOH