CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon


Question

Alkali metals react with water vigorously to form hydroxides and dihydrogen. Which of the following alkali metals reacts with water least vigorously?
(a) Li   (b) Na   (c) K    (d) Cs


Solution

(d)

Li has most negative standard reduction potential die to very high enthalpy of hydration . Thus, reaction of Li with water will be most exothermic, but surprisingly Li, reacts with water gently, whereas Na and K vigorously.
 The explanation is in kinetics and not in thermodynamics of the reaction. No doubt maximum energy is evolved with Li but its fusion, vaporisation and ionisation consume more energy. As a result reaction proceeds slowly.
 Na or K have low melting points and molten metal spreads over water exposing a larger surface to water, making the reaction vigorous.
 


Chemistry
NCERT Exemplar
Standard XI

Suggest Corrections
thumbs-up
 
0


similar_icon
Similar questions
View More


similar_icon
Same exercise questions
View More



footer-image