How can an unsaturated solution of a solid be made saturated?

Adding more solid.

Explanation:

Hello,

Based on the concern, it is known that an unsaturated solution is made when one adds an amount of the solid that is smaller than its solubility for the given amount of solute at the specified temperature, thus, to make a saturated solution, more solute must be added in order for it to equal the solubility at the very same amount of the solvent and at the same specified temperature.

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as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2