how many moles of hydrogen can be produced from 8.40g of aluminum and excess sodium hydroxide? how many grams?

Question

Stoichiometry 

Answer 1

The reaction for sodium hydroxide and aluminum is 2Al + 2NaOH + 2H₂O → 2NaAlO₂ + 3H₂.

First, Convert grams of aluminum into moles of aluminum by dividing the amount of aluminum in grams by the molar mass of aluminum.

8.40 g / 26.98 g per mole= 0.3113 moles of aluminum.

Second, use the stoichiometric coefficients from the equation to convert moles of aluminum into moles of hydrogen.

(0.3113 moles of aluminum / 2 moles of aluminum) * 3 moles of hydrogen= 0.467 moles of hydrogen

Third, multiply the moles of hydrogen by molar weight of hydrogen to find the number of grams of hydrogen produced by the aluminum. (Note that hydrogen is a diatomic element so you would need twice the molar mass of hydrogen)

0.467 moles of hydrogen * (1.008 g * 2) = 0.941 g of hydrogen.

Hope this helps!