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Checking a Rain Sensor With Blank Samples 4 questions
Checking a Rain Sensor With Blank Samples
Base your answers on the information provided and your knowledge of chemistry. Use the 2025 Chemistry Reference Tables as needed.
A class compares cups that hold rain samples for a model pH sensor. The same sensor reads a reference solution as pH 6.0 directly. Students pour matched portions into three cups, wait the same time, and read each portion. The class also uses pH 7.0 water as a blank.
| Cup | Blank pH after contact | Reference pH after contact |
|---|---|---|
| J | 7.0 | 6.0 |
| K | 5.9 | 5.5 |
| L | 7.0 | 6.4 |
Question 1
Which cup gives the intended reading for both liquids?
- J only
- K only
- L only
- J and L
Question 2
Use K’s blank reading to explain how the cup could affect a rain sample reading even if the sensor works properly.
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A student wants to approve a cup whenever its blank result matches pH 7.0. The class also wants the cups to work on weakly acidic samples.
Question 3
Use one cup’s results to show why the blank result alone cannot verify a cup for weakly acidic samples.
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Question 4
Describe a comparison to check whether a cleaning step improves cup L. Identify what should be held constant.
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