Question

What is the molarity of a 75.0 mL solution that contains 0.225 g of
potassium nitrate?

Answer 1

0.0297M

Step-by-step explanation:

We will use the formula M= moles of solute/lites of solution.

First we need to figure out the Moles of the solute, to get this we first need the molar mass of KNO3 (potassimum nitrate).

The Molar Mass of potassimum nitrate is 101.103 g/mol
K - 1 x 39.09
N - 1 x 14.006
O - 3 x 15.999
KNO3 - 101.103 g/mol

Now we get the moles of the solute by doing.
0225g/ 101.103g/mol = 0.00223 mol

Put the answer into the orginal equation to get 0.00223mol / 0.045 L
Which equals to 0.0297M. This is also the correct amount of significant figures.

Answer 2

M=0.0297M

Step-by-step explanation:

we know that molarity equals number of mole of solute over the volume of solution.

M=n/V but n=m/M

n=0.225g÷101g/mol =0.00223mol

M=0.00223mol/0.075l

M=0.0297M