Question

in part 1 of this lab, you will be calculating \\( \delta _ { mathrm { r } } mathrm { h } \\) by conducting constant - pressure calorimetry measurements.
one of the final steps in this calculation is obtaining \\( \delta _ { mathrm { r } } mathrm { h } \\) by taking the q value (with respect to the system) and dividing by n.
what number of moles (n) will you be using in the above formula?
select one:
number of moles of water
number of moles of magnesium, since mg is in the balanced chemical equation and is a part of the system

Explanation:

In constant - pressure calorimetry for reactions involving magnesium (e.g., \(Mg + 2HCl
ightarrow MgCl_{2}+H_{2}\uparrow\)), the enthalpy change of reaction \(\Delta_{r}H\) is calculated per mole of the limiting reactant (in this case, magnesium if it is the limiting reactant). Water is often a solvent or a by - product in such reactions and not the key species for calculating the reaction enthalpy per mole in the formula \(\Delta_{r}H=\frac{q}{n}\).

Answer:

Number of moles of magnesium, since \(Mg\) is in the balanced chemical equation and is a part of the system.