CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon


Question

The first and second dissociation constants of an acid $$H_{2}A$$ are $$1.0\times 10^{-5}$$ and $$5.0\times 10^{-10}$$ respectively. The overall dissociation constant of the acid will be:


A
5.0×1015
loader
B
5.0×1015
loader
C
0.2×105
loader
D
5.0×105
loader

Solution

The correct option is B $$5.0\times 10^{-15}$$
$${ H }_{ 2 }A\longleftrightarrow { HA }^{ - }+{ H }^{ + }$$
$${ K }_{ 1 }=\dfrac { \left[ { HA }^{ - } \right] \left[ { H }^{ + } \right]  }{ \left[ { H }_{ 2 }A \right]  } $$
$${ HA }^{ - }\longleftrightarrow { H }^{ + }+{ A }^{ 2- }$$
$${ K }_{ 2 }=\dfrac { \left[ { A }^{ 2- } \right] \left[ { H }^{ + } \right]  }{ \left[ { HA }^{ - } \right]  } $$
for the reaction, $${ H }_{ 2 }A\longleftrightarrow { A }^{ 2- }+{ 2H }^{ + }$$
$$K=\dfrac { \left[ { A }^{ 2- } \right] { \left[ { H }^{ + } \right]  }^{ 2 } }{ \left[ { H }_{ 2 }A \right]  } $$
$$K=\left( { K }_{ 1 } \right) \left( { K }_{ 2 } \right) $$
$$=1\times { 10 }^{ -5 }\times 5\times { 10 }^{ -10 }$$
$$=5\times { 10 }^{ -15 }$$
overall dissociation constant of acid will be $$5\times { 10 }^{ -15 }$$.

Chemistry

Suggest Corrections
thumbs-up
 
0


similar_icon
Similar questions
View More


similar_icon
People also searched for
View More



footer-image