# How Do You Calculate pH and [OH-] for a Mixed NH3 and NH4Cl Solution?

• Alex Santos
In summary, the conversation discusses calculating the hydroxide ion concentration and pH of a solution containing 500ml of 0.20M NH3(aq) and 500ml of 0.20M NH4Cl(aq). The Henderson Hasselbalch equation and the ICE table method are both used to solve the problem. The resulting pH values obtained from each method are 5.13 and 9.25 respectively. The full calculation can be found in the attached document.
Alex Santos

## Homework Statement

[/B]
NH3(aq) is a weak base with Kb = 1.8*10-5, Calculate [OH-] in a solution that is made by mixing togeather 500ml of 0.20M NH3(aq) and 500ml of 0.20M NH4CL(aq), what is the value of Ph?

## Homework Equations

Henderson Hasselbalch: ph = Pka + log([conj.base/acid])
As well as another approach on the example, the regular one.

## The Attempt at a Solution

To start with I am always a bit confused on how to set up the example and giving me the right inital values, for example I have NH4Cl---->NH3 + Cl + H. Now can I use my initial values, as NH3 in terms of moles
moles NH4Cl: 0.5L*0.2M = 0.1 moles
moles NH3: 0.5*0.2M = 0.1moles

using the " normal method" I get PH = 5.13 and by using the Hendersone Hasselbalch I get PH = 9.25.

I will send an attachment of my calculation because I write everything on an Ipad, so you can see clearly what I am doing.
Please correct me and tell me what is wrong and which method is wrong in my case.
Thank you

#### Attachments

• Note 19 Nov 2015 copy.pdf
642.3 KB · Views: 213
Solve full quadratic for the ICE table method.

## What is an acid-base reaction?

An acid-base reaction is a chemical reaction in which an acid and a base react to form a salt and water. It involves the transfer of protons (H+) from the acid to the base, resulting in the formation of a new compound.

## What is pH?

pH is a measure of the acidity or basicity of a solution. It is a scale ranging from 0 to 14, with 0 being the most acidic and 14 being the most basic. A pH of 7 is considered neutral, while a pH below 7 is acidic and a pH above 7 is basic.

## What is pOH?

pOH is the negative logarithm of the hydroxide ion concentration in a solution. It is used to measure the basicity of a solution, similar to how pH measures acidity. The pOH scale ranges from 0 to 14, with 0 being the most basic and 14 being the most acidic.

## How do you calculate pH?

pH can be calculated using the equation: pH = -log[H+], where [H+] is the concentration of hydrogen ions in moles per liter. Alternatively, pH can also be determined using a pH meter or pH paper.

## What factors affect the pH of a solution?

The pH of a solution can be affected by the concentration of hydrogen ions, temperature, and the presence of acids or bases. Adding an acid will decrease the pH, while adding a base will increase the pH. Temperature can also affect the equilibrium between acids and bases, thus changing the pH of a solution.

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