(A) What volume of the aluminum-copper alloy described in Example 4-5 must be dissolved in an excess of HCl(aq) to produce 1.00 g H₂?

(B) Afresh sample of the aluminum-copper alloy described in Example 4-5 yielded 1.31 g H₂. How many grams of copper were present in the sample?

Example 4-5

An alloy used in aircraft structures consists of 93.7% Al and 6.3% Cu by mass. The alloy has a density of 2.85 g/cm³. A 0.691 cm³ piece of the alloy reacts with an excess of HCl(aq). If we assume that all the Al but none of the Cu reacts with HCl(aq), what is the mass of H₂ obtained?