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Why Are Potassium and Cesium, Rather than Lithium Used in Photoelectric Cells? - CBSE (Science) Class 11 - Chemistry

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Question

Why are potassium and cesium, rather than lithium used in photoelectric cells?

Solution 1

All the three, lithium, potassium, and cesium, are alkali metals. Still, K and Cs are used in the photoelectric cell and not Li.

This is because as compared to Cs and K, Li is smaller in size and therefore, requires high energy to lose an electron. While on the other hand, K and Cs have low ionization energy. Hence, they can easily lose electrons. This property of K and Cs is utilized in photoelectric cells.

Solution 2

Potassium and caesium have much lower ionization enthalpy than that of lithium. As a result, these metals easily emit electrons on exposure to light. Due to this, K and Cs are used in photoelectric cells rather than lithium.

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APPEARS IN

 NCERT Solution for Chemistry Textbook for Class 11 (2018 to Current)
Chapter 10: The s-Block Elements
Q: 9 | Page no. 305
Solution Why Are Potassium and Cesium, Rather than Lithium Used in Photoelectric Cells? Concept: Group 1 Elements - Alkali Metals.
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