Aluminum–lithium (Al–Li) alloys have been developed by the aircraft industry to reduce the weight and improve the performance of its aircraft. A commercial aircraft skin material having a density of 2.14 g/cm3 is desired. Compute the concentration of Li (in wt%) that is required. The densities of aluminum and lithium are 2.71 and 0.534 g/cm3, respectively.

6.54% is the required concentration of lithium in an alloy (Al–Li).

Explanation:

Suppose 100 grams of an alloy of aluminium and lithium.

Density of an alloy = d  

Volume of an alloy = V

Volume of aluminum =

Mass of aluminum = x

Density of aluminum =

Volume of lithium =

Mass of lithium = y

Density of lithium=

..[1]

..[2]

Solving [1] and [2] :

we get :

x = 93.46 g

y = 6.54 g

Concentration of Li (in wt%) that is required: