What is the pH of an aqueous solution made by combining 35.01 mL of a 0.3791 M ammonium chloride with 40.07 mL of a 0.3542 M solution of ammonia to which 3.112 mL of a 0.0896 M solution of HCI was added?

pH = 9.25

Explanation:

Using H-H equation:

pH = pKa + log [A⁻] / [HA]

Where pH is pH of the buffer

pKa is pKa of the weak acid: 9.24

[A⁻] could be taken as moles of the conjugate base: Moles NH₃

[HA] moles of the weak acid: NH₄⁺

Initial moles of NH₃:

40.07mL = 0.04007L * (0.3542mol / L) = 0.01419mol

Initial moles NH₄⁺:

0.03501L * (0.3791mol / L) = 0.01327 mol

The HCl added reacts with NH₃ producing NH₄⁺:

HCl + NH₃ → NH₄⁺ + Cl⁻

Moles of HCl:

3.112x10⁻³L * (0.0896mol / L) = 0.00028 moles

That means moles of NH₃ and NH₄⁺ after the addition of HCl are:

NH₄⁺: 0.01327moles + 0.00028moles = 0.01355 moles

NH₃: 0.01419mol - 0.00028 moles = 0.01391 moles

pH of the buffer is:

pH = pKa + log [A⁻] / [HA]

pH = 9.24 + log [0.01391 moles] / [0.01355 moles]

they both have a y in them

conduction is the transfer of thermal energy (heat in transfer) due to collisions between the molecules in the object. collisions between adjacent atoms and molecules transfer kinetic energy from the warmer to the cooler object. the objects must be in physical contact.