Question

A solution is made by dissolving 0.565 g of potassium nitrate in enough water to make up 250. mL of solution. What is the molarity of this solution?

Please explain and show work.

Answer 1

Molar mass of Potassium Nitrate:-

$\\ \large\sf\longmapsto KNO_3$

$\\ \large\sf\longmapsto 39u+14u+3(16u)$

$\\ \large\sf\longmapsto 53u+48u$

$\\ \large\sf\longmapsto 101u$

$\\ \large\sf\longmapsto 101g/mol$

Now

$\boxed{\sf No\:of\:moles=\dfrac{Given\:mass}{Molar\:mass}}$

$\\ \large\sf\longmapsto No\:of\:moles=\dfrac{0.565}{101}$

$\\ \large\sf\longmapsto No\:of\:moles=0.005mol$

We know

$\boxed{\sf Molarity=\dfrac{Moles\:of\:solute}{Vol\:of\:Solution\:in\:L}}$

$\\ \large\sf\longmapsto Molarity=\dfrac{0.005}{\dfrac{250}{1000}L}$

$\\ \large\sf\longmapsto Molarity=\dfrac{0.005}{0.250}$

$\\ \large\sf\longmapsto Molarity=0.02M$

Answer 2

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