When 10 g of an alloy consisting of zinc and copper is dissolved in an excess of alkali solution, its mass decreases by 6 g.
| November 23, 2020 | education
When 10 g of an alloy consisting of zinc and copper is dissolved in an excess of alkali solution, its mass decreases by 6 g. Determine the mass fraction of copper in the alloy (%).
Only zinc will react with alkali
Zn + 2NaOH + 2 H2O = Na2 [Zn (OH) 4] + H2
since copper cannot displace hydrogen
Therefore, the mass of zinc in the alloy is 6 g, the mass of copper is 4 g. 4/10 = 0.4 or 40%
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