Name: Bragg's Equation and Its Application
Uploaded: 2019-07-19
Duration: 2 min 37 s
Description: Bragg's equation gives the d-spacing between the crystal lattice planes of atoms that produces the constructive interference. Let's watch the video to learn...

Question

The diagram shows the enthalpy changes when sodium chloride is dissolved in water.

Name the enthalpy changes labelled A, B and C.

Accepted Answer

In step A, gaseous ions are combining to form an ionic solid crystal. Therefore, the equation represents the lattice enthalpy, $∆ H_{latt}^{}$ for $NaCl$ .

${Na}^{+} (g) + {Cl}^{-} (g) \to NaCl (s)$

In step B, gaseous ions ${Na}^{+}$ and ${Cl}^{-}$ dissolves in sufficient water to form a very dilute solution. Therefore, the equation represents the enthalpy change of hydration, $∆ H_{hyd}^{}$ .

${Na}^{+} (g) + {Cl}^{-} (g) + aq \to {Na}^{+} (aq) + {Cl}^{-} (aq)$

In step C, $1 mole$ of ionic solid, $NaCl$ dissolves in sufficient water to form a very dilute solution. Therefore, the equation represents the standard enthalpy change of solution, $∆ H_{sol}^{}$ for $NaCl$ .

$NaCl (s) \to {Na}^{+} (aq) + {Cl}^{-} (aq)$

The diagram shows the enthalpy changes when sodium chloride is dissolved in water.

Name the enthalpy changes labelled A, B and C.

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