Sodium hydroxide reacts with aluminum and water to produce hydrogen gas:2 Al(s) + 2 NaOH(aq) + 6 H2O(l) → 2 NaAl(OH)4(aq) + 3 H2(g)What mass of hydrogen gas would be formed from a reaction of 1.33 g Al and 4.25 g NaOH in water?

Respuesta :

Answer: 0.147 grams

Explanation:

To calculate the moles :

[tex]\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}[/tex]    

[tex]\text{Moles of} Al=\frac{1.33g}{27g/mol}=0.049moles[/tex]

[tex]\text{Moles of} NaOH=\frac{4.25g}{40g/mol}=0.106moles[/tex]

[tex]2Al(s)+2NaOH(aq)+6H_2O(l)\rightarrow Na(Al(OH)_4(aq)+3H_2(g)[/tex]

According to stoichiometry :

2 moles of [tex]Al[/tex] require = 2 moles of [tex]NaOH/tex]

Thus 0.049 moles of [tex]Al[/tex] will require=[tex]\frac{2}{2}\times 0.049=0.049moles[/tex]  of [tex]NaOH[/tex]

Thus [tex]Al[/tex] is the limiting reagent as it limits the formation of product and [tex]NaOH[/tex] is the excess reagent.

As 2 moles of [tex]Al[/tex] give = 3 moles of [tex]H_2[/tex]

Thus 0.049 moles of [tex]Al[/tex] give =[tex]\frac{3}{2}\times 0.049=0.0735moles[/tex]  of [tex]H_2[/tex]

Mass of [tex]H_2=moles\times {\text {Molar mass}}=0.0735moles\times 2g/mol=0.147g[/tex]

Thus 0.147 g of [tex]H_2[/tex] will be produced from the given masses of both reactants.