To calculate the unknown molar concentration of CH3NH2 in MeOH titrated against a known molar concentration of HCl, you will need to use the concept of stoichiometry and the balanced chemical equation for the reaction between CH3NH2 and HCl.
First, let's write the balanced chemical equation for the reaction:
CH3NH2 + HCl → CH3NH3+ + Cl-
The stoichiometry of the reaction indicates that 1 mole of CH3NH2 reacts with 1 mole of HCl to form 1 mole of CH3NH3+ and 1 mole of Cl-. Therefore, the ratio of moles of CH3NH2 to moles of HCl is 1:1.
The titration involves adding a known volume and molar concentration of HCl to a solution of CH3NH2 in MeOH until the reaction is complete. At the equivalence point, the moles of HCl added will be equal to the moles of CH3NH2 present in solution.
To calculate the unknown molar concentration of CH3NH2, you will need the known molar concentration of HCl and the volume of HCl added at the equivalence point.
Let's denote:
C(CH3NH2) = molar concentration of CH3NH2 in MeOH (unknown)
C(HCl) = molar concentration of HCl (known)
V(HCl) = volume of HCl added at the equivalence point
Using the equation for molarity, which is defined as moles of solute divided by volume of solution in liters, we can set up the following equation based on the stoichiometry of the reaction:
C(CH3NH2) * V(CH3NH2) = C(HCl) * V(HCl)
Since the stoichiometry of the reaction is 1:1, the volume of CH3NH2 added is equal to the volume of HCl added at the equivalence point. Therefore, V(CH3NH2) = V(HCl).
Now, let's rearrange the equation to solve for the unknown molar concentration of CH3NH2:
C(CH3NH2) = (C(HCl) * V(HCl)) / V(CH3NH2)
By substituting the values of C(HCl) and V(HCl) with the known values, and measuring the volume of CH3NH2 added at the equivalence point, you can calculate the molar concentration of CH3NH2 in MeOH.
Remember to use proper units, such as molarity (mol/L) for concentrations and volume in liters, to ensure accurate calculations.