Answer:
The molarity of a solution of KCl is 1.33 ![\frac{moles}{L}](https://tex.z-dn.net/?f=%5Cfrac%7Bmoles%7D%7BL%7D)
Explanation:
The Molarity (M) or Molar Concentration is the number of moles of solute that are dissolved in a given volume. In other words, the molarity is the number of moles of solute per liter of solution.
Molarity is determined by the expression:
![Molarity(M)=\frac{number of moles}{volume}](https://tex.z-dn.net/?f=Molarity%28M%29%3D%5Cfrac%7Bnumber%20of%20moles%7D%7Bvolume%7D)
Molarity is expressed in units (
).
So in this case you need to know the number of moles. For that you must know the molar mass of KCl. You know:
- K= 39.10 g/mol
- Cl= 35.45 g/mol
So the molar mass of KCl is: KCl= 39.10 g/mol + 35.45 g/mol= 74.55 g/mol
Then the following rule of three applies: if 74.55 grams of KCl are in 1 mole, 149.2 grams of KCl in how many moles will they be?
![moles=\frac{149.2 g*1 moles}{74.55 g}](https://tex.z-dn.net/?f=moles%3D%5Cfrac%7B149.2%20g%2A1%20moles%7D%7B74.55%20g%7D)
moles= 2
So you know:
- number of moles= 2
- volume= 1500 mL=1.5 L (being 1 L=1000 mL)
Replacing in the definition of molarity:
![Molarity =\frac{2 moles}{1.5 L}](https://tex.z-dn.net/?f=Molarity%20%3D%5Cfrac%7B2%20moles%7D%7B1.5%20L%7D)
Solving:
Molarity= 1.33 ![\frac{moles}{L}](https://tex.z-dn.net/?f=%5Cfrac%7Bmoles%7D%7BL%7D)
The molarity of a solution of KCl is 1.33 ![\frac{moles}{L}](https://tex.z-dn.net/?f=%5Cfrac%7Bmoles%7D%7BL%7D)