What is a disadvantage of using pH indicators?
A solution of Acetic acid has a light red color in the presense of the indicator orange IV. When sodium acetate is added to the solution, the color changes to yellow. Explain the reaction which causes the color change.
I have no idea. Does it have to do with the sodium added? I don't understand. Help please!
Disadvantage of using pH indicators for what? For titrations it is that not all indicators change at the equivalence point pH. If for determining the pH of a solution, it is because most pH indicators have a pH range of about 2 pH units which isn't very close if you want to know the pH closer than 2 pH units.
Joyce, you should have posted your question separately. There is a good chance it will get overlooked by piggy backing on another question.
The answer is that acetic acid/sodium acetate mixtures form a buffered solution. The addition of the acetate changes the pH enough that the indicator changes.
You can calculate the change in pH if you have enough information to plug into the Henderson-Hasselbalch equation which is pH = pKa + log(base/acid).
A disadvantage of using pH indicators is that they provide only a rough estimation of the pH value. pH indicators are chemical compounds that change color in response to changes in pH. They are often used in educational and laboratory settings to determine the acidity or alkalinity of a solution. However, pH indicators have limitations in terms of accuracy and precision.
One major disadvantage is that pH indicators only provide a qualitative measurement of pH, rather than a quantitative one. They do not give an exact numeric value of the pH level, but rather indicate whether the solution is acidic, neutral, or alkaline. This can be a limitation when precise and accurate pH measurements are required. In contrast, pH meters or pH probes provide much more accurate and precise pH measurements.
Another disadvantage is that pH indicators have a limited pH range in which they can effectively change color. Different pH indicators have different ranges at which they undergo color changes. For example, some indicators may only be effective in the pH range of 5-9, while others may not work well in highly acidic or highly alkaline solutions. This limitation can restrict the applicability of pH indicators to certain types of solutions.
It is important to note that these disadvantages can be mitigated depending on the specific needs and requirements of the experiment or application. In some cases, the rough estimation provided by pH indicators may be sufficient, especially in educational or basic qualitative analysis. However, for more advanced research or precise pH measurements, alternative methods such as pH meters or specific chemical indicators may be preferred.