If all of the scn- is complexed with fe3+ to form fencs2+ what is the molar concentration of fencs2+

number of moles of SCN⁻ = 0 .001 X 3 / 1000 = 3 X 10⁻⁶ moles    in the 25 ml of solution

2) SCN⁻ + Fe³⁺ ===> FeNCS²⁺

1 mole SCN⁻ produces 1 mole of FeNCS²⁺

Therefore moles of FeNCS²⁺ in 25 ml = 3 X 10⁻⁶

Molar Concentration of FeNCS²⁺ = (3 X10⁻⁶ )X 1000 / 25 = 1.2 X 10⁻⁴ Moles / liter

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