Question

The table shows a chemical equation and the dimensional analysis used by a student to calculate the number of moles of Ba3N2 required to produce 6.7 moles of Ba(OH)2. Student's Dimensional Analysis Chemical Equation Dimensional Analysis Ba3N2 + 6H2O → 3Ba(OH)2 + 2NH3 3 mol of Ba(OH)2 x 1 mol of Ba3N2 / 6.7 mol of Ba(OH)2 What is the error in the dimensional analysis?

Answer 1

Answer:

The error is in the rule of three.

3 mol of Ba(OH)2 ___ comes from ____ 1 mol Ba3N2

6.7 mol of Ba(OH)2 ___ comes from ___ (6.7 .1) / 3

Explanation:

Ba3N2 + 6H2O → 3Ba(OH)2 + 2NH3

3 mol of Ba(OH)2 x 1 mol of Ba3N2 / 6.7 mol of Ba(OH)2

- The rule of three is wrong.

- The chemical equation is ballanced.

- The question is not clear about which is the limiting reactant. May be we don't have enough water, so that's the limiting and Ba3N2 is in excess. So have to work with H2O.

Answer 2

Answer:

Its arrangement.

Explanation:

Hello,

In this case, we rewrite the chemical reaction as:

$Ba_3N_2+6H_2O-->3Ba(OH)_2+2NH_3$

Now, a more organized dimensional analysis is shown below to determine the very same required value:

$n_{Ba_3N_2}=6.7molBa(OH)_2*\frac{1molBa_3N_2}{3molBa(OH)_2}$

Without giving the numerical answer, one sees that the student's dimensional analysis is wrongly written as long as the 3 moles of $Ba(OH)_2$ must be dividing rather than multiplying as it is the relationship factor used to relate it with the $Ba_3N_2$ based on the reaction stoichiometry. Moreover, the 6.7moles of $Ba(OH)_2$ must be multiplying as it is the starting value.

Best regards.