Aqueous sulfuric acid H2SO4 will react with solid sodium hydroxide NaOH to produce aqueous sodium sulfate Na2SO4 and liquid water H2O. Suppose 62. g of sulfuric acid is mixed with 33.8 g of sodium hydroxide. Calculate the minimum mass of sulfuric acid that could be left over by the chemical reaction. Round your answer to 2 significant digits.

Approximately .

Explanation:

(a diprotic acid) reacts with (a monoprotic base) at a one-to-two ratio:

.

In other words, if and represent the number of moles of the two compounds reacted, then:

.

Look up the relative atomic mass data on a modern periodic table:

Calculate the (molar) formula mass of and :

.

.

Calculate the number of moles of formula units in that of :

.

Apply the ratio to find the (maximum) number of moles of that would react with the of :

.

Calculate the mass of that of :

.

When the maximum amount of is reacted, the minimum would be in excess. Hence, the minimum mass of

(rounded to two significant figures.)

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