A 25.00 g sample of an unknown metal is heated to 100.0°C. It is then placed in a coffee-cup calorimeter filled with water. The water has a mass of 500.0 g and an overall specific heat of 4.184 J/g.°C. The initial temperature
of the water is 10.0°C. The system reaches a final thermal equilibrium temperature of 11.0°C when the metal is
added.
What is the specific heat of the metal?

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