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How many grams of concentrated nitric acid solution should be used to prepare 250 mL of 2.0 M $HNO_3$? The concentrated acid is 70% $HNO_3$.
A
54.0 g conc. $HNO_3$
B
45.0 g conc. $HNO_3$
C
90.0 g conc. $HNO_3$
D
70.0 g conc. $HNO_3$
Detailed Solution
$M = \frac{W\times1000}{M_w\times V_{solution}(mL)} \Rightarrow 2 = \frac{W\times1000}{63\times250}$
$W = 31.5$ g of $HNO_3$
70% $HNO_3$ means 70 g $HNO_3$ in 100 g solution.
31.5 g $HNO_3$ is present in $\frac{100}{70}\times31.5 = 45$ g of solution.
$W = 31.5$ g of $HNO_3$
70% $HNO_3$ means 70 g $HNO_3$ in 100 g solution.
31.5 g $HNO_3$ is present in $\frac{100}{70}\times31.5 = 45$ g of solution.