What mass of HNO3 (MM=63) is present in 50. mL of a 1.5 M solution?
Remember that molarity volume will give you moles. And then using the molar mass, you can find the mass.
1.5 M 0.050 L = 0.075 moles HNO₃
0.075 moles * (63 grams/1mole) = 4.7 grams HNO₃
We are limited to 2 significant figures because of the molarity.
The mass of HNO₃ is 4.7 grams.
Molarity = number of moles
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volume of the solution
1.5 = number of moles of HNO3
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50 x 10^-3
Therefore, number of moles of HNO3 = 50 x 10^-3 x 1.5 = 0.075 moles.
Therefore, mass of HNO3 = moles x molar mass of HNO3
= 0.075 x 63
= 4.725 grams.