Cunife 1 The Special Alloy

Chemistry Level 5

Cunife 1 is an alloy used in making wires in light bulbs and thermionic valves. It composes of copper, nickel and iron. A \(10.00\text{ g}\) sample of Cunife 1 was immersed in an \(\ce{HCl}\) bath, and \(854.94 \text{ mL}\) of hydrogen gas was collected under \(2\text{ atm}\) and \(298.15 \text{ K}\). However, one metal in the alloy was purely unoxidized. Another \(10.00\text{ g}\) sample of Cunife 1 at \(100^\circ C\) was then dumped in a calorimeter containing \(50.00\text{ g}\) water at \( 10.00^\circ C\) and at thermal equilibrium the temperature of the metal-water mixture was measured at \(11.738^\circ C\) by the calorimeter’s thermistor. What is the percent composition (by mass) of copper in Cunife 1?

Hint: One of the metals cannot be oxidized by \(\ce{HCl}\).

Details and Assumptions:

  • Universal Gas Constant \(R = 0.08206 \text{L atm/(mol K)} \).

  • Specific heat in \(\text{J/(g K)}\): \(\ce{Cu}\) – 0.39, \(\ce{Ni}\) – 0.44, \(\ce{Fe}\) – 0.45, \(\ce{H2O}\) – 4.184

  • Molar mass in \(\text{g/mol}\): \(\ce{Cu}\) – 63.55, \(\ce{Ni}\) – 58.69, \(\ce{Fe}\) – 55.85.


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