Question

How many grams of a stock solution that is 92.5 percent H2SO4 by mass would be needed to make 250 grams of a 35.0 percent by mass solution? Show all of the work needed to solve this problem.

Answer 1

94.6 g.  You must use 94.6 g of 92.5 % H_2SO_4 to make 250 g of 35.0 % H_2SO_4.

We can use a version of the dilution formula

m_1C_1 = m_2C_2

where

m represents the mass and

C represents the percent concentrations

We can rearrange the formula to get

m_2= m_1 × (C_1/C_2)

m_1 = 250 g; C_1 = 35.0 %

m_2 = ?; _____C_2 = 92.5 %

∴ m_2 = 250 g × (35.0 %/92.5 %) = 94.6 g