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Calculate the pH of a 1.2 M NH3 solution at 25∘C.

A) >7
B) <7
C) =7
D) Cannot be determined

1 Answer

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Final answer:

The pH of a 1.2 M NH3 solution is greater than 7, indicating the solution is basic. Precise calculations would need the Kb value for NH3, but given data from a similar concentration suggests a pH much higher than 7.

Step-by-step explanation:

The question asks us to calculate the pH of a 1.2 M ammonia (NH3) solution. Since NH3 is a weak base, it will react with water to form NH4+ and OH-. The equation for this reaction is NH3(aq) + H2O(l) ⇒ NH4+(aq) + OH-(aq). Ammonia's Kb (base dissociation constant) would be needed for precise calculations, but it can also be determined using its pH value given for a 0.950-M solution, which is 11.612. This pH is significantly higher than 7, indicating that the solution is basic. Considering that the pH is a logarithmic scale, a small increase in OH- concentration can result in a significant increase in pH.

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