You make a solution of stannous fluoride by mixing 100 g of SnF2 in 2.00 L of water in a beaker. What is the molarity, or moles/L, of the resulting solution, assuming all of the solute dissolves?
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To do this you first need to figure out the moles of SnF2 that were dissolved. To do this all you need to know is the molar mass of SnF2 and the amount of SnF2 used.
Molar Mass of SnF2 = (MM of Sn) + 2(MM of F) Molar Masses can be found on the periodic table.
So
(118.71) + 2(18.99) = 156.7g in one mol SnF2.
Then take the mass of the SnF2 used and divide it by the molar mass of SnF2.
100/156.7 = 0.64mol SnF2.
Now to find Molarity all you need to do is take the moles of SnF2 and divide them by the liters of the water. (moles/L)
0.64 / 2 = 0.32 molarity SnF2
Molar Mass of SnF2 = (MM of Sn) + 2(MM of F) Molar Masses can be found on the periodic table.
So
(118.71) + 2(18.99) = 156.7g in one mol SnF2.
Then take the mass of the SnF2 used and divide it by the molar mass of SnF2.
100/156.7 = 0.64mol SnF2.
Now to find Molarity all you need to do is take the moles of SnF2 and divide them by the liters of the water. (moles/L)
0.64 / 2 = 0.32 molarity SnF2