Ammonia, NH₃, is very soluble in water (51.8 g/L at 20 °C and 760 mmHg). Show how NH₃ can hydrogen bond to water.

Verified step by step guidance

1. Identify the hydrogen bonding capability of NH₃: Ammonia (NH₃) has a nitrogen atom bonded to three hydrogen atoms. The nitrogen atom has a lone pair of electrons, making it capable of forming hydrogen bonds.
2. Identify the hydrogen bonding capability of water: Water (H₂O) has an oxygen atom bonded to two hydrogen atoms. The oxygen atom has two lone pairs of electrons, and the hydrogen atoms are partially positive, making water capable of forming hydrogen bonds.
3. Understand the nature of hydrogen bonds: A hydrogen bond is a type of dipole-dipole interaction that occurs between a hydrogen atom, which is covalently bonded to a more electronegative atom (like N, O, or F), and another electronegative atom with a lone pair of electrons.
4. Visualize the hydrogen bond formation: In the case of NH₃ and H₂O, the lone pair of electrons on the nitrogen atom in NH₃ can form a hydrogen bond with one of the hydrogen atoms in H₂O. Alternatively, the lone pair of electrons on the oxygen atom in H₂O can form a hydrogen bond with one of the hydrogen atoms in NH₃.
5. Draw the interaction: Represent the hydrogen bond as a dashed line between the hydrogen atom of one molecule and the lone pair of the electronegative atom of the other molecule. For example, NH₃'s nitrogen lone pair can form a hydrogen bond with a hydrogen atom of H₂O, or H₂O's oxygen lone pair can form a hydrogen bond with a hydrogen atom of NH₃.

Key Concepts

Hydrogen Bonding

Hydrogen bonding is a type of weak chemical bond that occurs when a hydrogen atom covalently bonded to a highly electronegative atom, such as oxygen or nitrogen, experiences an attraction to another electronegative atom. In the case of ammonia (NH₃) and water (H₂O), the hydrogen atoms of NH₃ can form hydrogen bonds with the oxygen atom of water, leading to increased solubility.

Polarity of Molecules

Polarity refers to the distribution of electrical charge over the atoms in a molecule. Water is a polar molecule due to its bent shape and the difference in electronegativity between hydrogen and oxygen, which creates a partial positive charge on the hydrogen atoms and a partial negative charge on the oxygen atom. Ammonia is also polar, allowing it to interact favorably with water through hydrogen bonding.

Solubility Principles

Solubility is the ability of a substance to dissolve in a solvent, which is influenced by the nature of both the solute and the solvent. The principle 'like dissolves like' suggests that polar solutes, such as ammonia, are more soluble in polar solvents like water. The hydrogen bonding between NH₃ and H₂O enhances this solubility, allowing ammonia to dissolve effectively in water.