The table below shows the color of three indicators at different pH values.
Indicator pH=0 pH=2 pH=4 pH=6 pH=8 pH=10 pH=12 ph=14
Litmus paper Red Red Red Red Blue Blue Blue Blue
Phenolphthalein No change No change No change No change No change Pink Pink Pink
Thymol blue Red Red Yellow Yellow Yellow Blue Blue Blue
An unknown liquid is tested with three indicators:
• The unknown liquid turns litmus paper blue.
• The unknown liquid is not affected by phenolphthalein indicator.
• The unknown liquid turns yellow when tested with thymol blue indicator.
What is the pH of the unknown solution?
A.
2
B.
6
C.
8
D.
12
Based on the information given, we can determine the pH of the unknown solution.
Litmus paper turns blue at pH 8 and above, so the unknown liquid has a pH of 8 or higher.
The phenolphthalein indicator does not change color, indicating that the pH of the unknown liquid is not within the range where phenolphthalein can detect a change.
Thymol blue turns yellow at pH values between 2 and 6, implying that the pH of the unknown liquid is within this range.
Based on these observations, the pH of the unknown solution is most likely 2.
Therefore, the correct answer is A. 2
Based on the information provided, we can determine the pH of the unknown solution by matching the given observations with the color changes of indicators at different pH values.
From the given observations:
1. The unknown liquid turns litmus paper blue. According to the table, litmus paper turns blue at pH 8.
2. The unknown liquid is not affected by phenolphthalein indicator. According to the table, phenolphthalein does not change color at any pH value mentioned.
3. The unknown liquid turns yellow when tested with thymol blue indicator. According to the table, thymol blue turns yellow at pH 4 and pH 6.
Considering all the information, we can conclude that the pH of the unknown solution is pH 8 (as litmus paper turns blue at that pH).
Therefore, the correct answer is C. 8.
To determine the pH of the unknown solution, we need to analyze the information provided for each indicator.
1. Litmus paper: The unknown liquid turns litmus paper blue. According to the table, litmus paper turns blue at pH 8 or higher. This means that the pH of the unknown solution is at least 8.
2. Phenolphthalein: The unknown liquid is not affected by phenolphthalein indicator. According to the table, phenolphthalein remains colorless (no change) at all pH values mentioned. This information does not help us determine the pH of the unknown solution.
3. Thymol blue: The unknown liquid turns yellow when tested with thymol blue indicator. According to the table, thymol blue turns yellow at pH 4 or lower. This means that the pH of the unknown solution is less than 4.
Combining the information from both litmus paper and thymol blue, we can conclude that the pH of the unknown solution is between 4 and 8. Therefore, the correct answer is:
B. 6