Answer:
Explanation:
To prepare an ammonia buffer solution for checking water hardness, you'll need a few materials and follow specific steps. Here's a general procedure:
Materials Needed:
1. Ammonium chloride (NH4Cl)
2. Ammonia solution (concentrated or household ammonia)
3. Distilled water
4. pH meter or pH indicator paper/strips
5. Glassware (beaker, flask, or graduated cylinder)
6. Stirring rod or magnetic stirrer (optional)
Procedure:
1. Calculate the desired pH of your buffer solution. For checking water hardness, a pH of around 10 is typically suitable.
2. Determine the required concentrations of ammonium chloride (NH4Cl) and ammonia (NH3) needed to achieve the desired pH. You can use a buffer calculator or tables to help with this calculation.
3. Measure out the appropriate amounts of ammonium chloride (NH4Cl) and ammonia solution (NH3). The molar ratio of NH4Cl to NH3 will depend on the desired pH. For example, for a pH of 10, the ratio is usually around 1:1.
4. Add the measured amount of ammonium chloride (NH4Cl) to a clean container (such as a beaker or flask).
5. Add distilled water to the container until the desired volume is reached. The volume will depend on how much buffer solution you need. Typically, a volume of 100 mL or more is sufficient for laboratory testing.
6. Stir the solution until the ammonium chloride (NH4Cl) is completely dissolved. If you have a magnetic stirrer, you can use it for efficient mixing.
7. Slowly add the measured amount of ammonia solution (NH3) to the solution while stirring continuously. Be cautious as ammonia solution is corrosive and emits fumes. Perform this step in a well-ventilated area or under a fume hood.
8. Check the pH of the solution using a pH meter or pH indicator paper/strips. Adjust the pH if necessary by adding more ammonium chloride (for lower pH) or more ammonia solution (for higher pH).
9. Once you've reached the desired pH, the ammonia buffer solution is ready for use in checking water hardness.
10. Store the buffer solution in a labelled, tightly sealed container. Keep it away from direct sunlight and extreme temperatures to maintain its stability.
