What is the molarity of a solution in which 6.9 potassium chloride is dissolved in water to make a final volume of 1.8L?

Case 1 : 6.9 moles

Molarity
= (No. of moles of solute) / (Volume of solution in L)
= (6.9 mol) / (1.8 L)
= 3.83 M


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Case 2 : 6.9 g

The solute of KCl.
Molar mass of KCl = (39.01 + 35.45) g/mol = 74.46 g/mol
No. of moles of KCl = (6.9 g) / (74.46 g/mol) = (6.9/74.46) mol

Molarity
= (No. of moles of KCl) / (Volume of solution in L)
= [(6.9/74.46) mol] / (1.8 L)
= 0.0515 M