Balance the following Equation: ___Zn + ___HCl --> ___ZnCl2 + ___H2

50g of zinc are reacted with 50g of hydrogen chloride. What is the limiting reactant?

Group of answer choices

HCl

ZnCl2

Zn

H2

HCl

Explanation:

Given data:

Mass of Zn = 50 g

Mass of HCl = 50 g

Limiting reactant = ?

Solution:

Chemical equation:

Zn + 2HCl      →     ZnCl₂ + H₂

Number of moles of Zn:

Number of moles = mass / molar mass

Number of moles = 50 g/ 65.38 g/mol

Number of moles = 0.76 mol

Number of moles of HCl:

Number of moles = mass / molar mass

Number of moles = 50 g/ 36.5 g/mol

Number of moles = 1.4 mol

Now we will compare the moles of Reactant with product.

                 Zn         :          ZnCl₂

                  1           :             1

                 0.76     :           0.76

                Zn         :             H₂

                  1           :             1

                 0.76     :           0.76

               HCl         :          ZnCl₂

                  2           :             1

                 1.4         :           1/2×1.4 = 0.7

                HCl         :             H₂

                  2           :             1

                 1.4         :           1/2×1.4 = 0.7

Less number of moles of product are formed by HCl it will act limiting reactant.

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.