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 2.42 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.

The concentration of Li (in wt%) is 3,47g/mol

Explanation:

To obtain the 2,42g/cm³ of density:

2,42g/cm³ = 2,71g/cm³X + 0,534g/cm³Y (1)

Where X is molar fraction of Al and Y is molar fraction of Li.

X + Y = 1 (2)

Replacing (2) in (1):

Y = 0,13

Thus, X = 0,87

The weight of Al and Li is:

0,87*26,98g/mol = 23,4726 g of aluminium

0,13*6,941g/mol = 0,84383 g of lithium

The concentration of Li (in wt%) is:

0,84383g/(0,84383g+23,4726g) ×100= 3,47%

in chemistry, adhesion and cohesion are attractive forces that exist between molecules. they hold the molecules together from each other. they are different in that adhesive force exists between molecules of different substance while cohesive force happens between molecules of same substance.

adhesion between water and glass causes water molecules at the edge of water and glass interface to climb up the wall in a narrow glass tube. this is called capillary action. cohesion is what gives glass its shape and causes water to form a droplet.