Calculate the pH of a buffer that is prepared by mixing 25.0 mL of 0.300 M methylamine (CH3NH2) and 0.405 g of methylammonium chloride with water to make 500.0 mL of solution.

The pH of the solution is 10.74

Explanation:

To calculate the number of moles, we use the equation:

Given mass of methylammonium chloride = 0.405 g

Molar mass of methylammonium chloride = 67.52 g/mol

Putting values in above equation, we get:

To calculate the number of moles for given molarity, we use the equation:

Molarity of methylamine solution = 0.300 M

Volume of solution = 25 mL = 0.025 L

Putting values in above equation, we get:

Total volume of the solution = [25 + 500] = 525 mL = 0.525 L   (Conversion factor: 1 L = 1000 mL)

To calculate the pOH of basic buffer, we use the equation given by Henderson Hasselbalch:  

We are given:  

= negative logarithm of base dissociation constant of methylamine = 3.36

pOH = ?

Putting values in above equation, we get:

To calculate the pH of the solution, we use the equation:

Hence, the pH of the solution is 10.74

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.

o conteúdo de calor de um sistema é igual à entalpia apenas para um sistema que é constante