A solution of methylamine ( CH3NH2 ), a weak base, has an initial concentration of 0.195 M. Methylamine has a Kb of 4.4×10−4. Calculate the pH of the solution.

12

Explanation:

Let's consider the basic reaction of methylamine.

CH₃NH₂ + H₂O ⇄ CH₃NH₃⁺ + OH⁻

The concentration of the weak base is Cb = 0.195 M and the basic dissociation constant is Kb = 4.4 × 10⁻⁴. We can calculate the concentration of OH⁻ using the following expression.

[OH⁻] = √(Kb × Cb)

[OH⁻] = √(4.4 × 10⁻⁴ × 0.195) = 9.3 × 10⁻³ M

The pOH is:

pOH = -log [OH⁻] = -log 9.3 × 10⁻³ = 2.0

The pH is:

pH + pOH = 14

pH = 14 - pOH = 14 - 2.0 = 12

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

if it's not useful, feel free to report for mistake in answer.