SOLID CARBON DIOXIDE

By: Hayley and Mae

Molecular solids Solids made of separate molecules packed together are known as

discrete molecular substances. From the word molecular means composed of molecules. There are two forces present in discrete molecular substances. The forces within the molecule-intramolecular forces-are the

covalent bond linking atoms in individual molecules. Covalent bond consist of shared paired of electrons. These electrons

must exist between the atoms sharing them. The forces between the molecules-intermolecular forces-link

individual molecules to each other. Intramolecular forces are very strong. Intermolecular forces are much weaker than intramolecular forces. Intermolecular forces determine the physical properties of discrete

molecular substances. Polar molecular substances are generally soluble in water. Non-polar molecular substances are generally insoluble in water.

Solid Carbon Dioxide

Solid Carbon Dioxide (dry ice) is a solid at room temperature and sublimes (turns directly into gas) because the forces between the molecules (ie.The intermolecular forces) are very weak. The carbon dioxide molecule (O=C=O) contains two double bonds, 2 hydrogen atom bonded to a single carbon atom and has a linear shape.

When the substance sublimes the intramolecular forces (ie. Covalent bond) remain intact. The molecules do not break down- they simply separate between molecules due to heat energy.

The regular arrangement of molecules are held together by weak forces.

Solid Carbon Dioxide is made entirely of molecules. The atoms are non-metal atoms that is covalently bonded

together. Separate molecules are linked together by weak van der Waals

forces (VdW). VdW’s forces result from long range attraction of electrons in 1

molecule for protons in an adjacent molecules & vice versa. The low temperature and direct sublimation to a gas makes dry ice

an effective coolant (a fluid that flows through a device to prevent from over heating), since it is colder than water ice and leaves no residue as it changes state.

Solid carbon dioxide or also known as dry ice is non-polar,which means it is symmetrical and cancel each other out, and with a dipole moment of zero, so attractive intermolecular van deer Waals forces operate. The composition results in low melting and boiling point temperature and electrical conductivity.

Properties of Solid Carbon Dioxide

• Melting and Boiling point Low melting point (mp) & Boiling point (bp) Soft

• Electrical Conductivity Electricity is flow charged particles. Since Solid Carbon Dioxide is consists of molecules and not

charged particles they do not conduct electricity (no free electrons of ions)

• Solubility of Solid Carbon Dioxide Carbon Dioxide is non-polar molecular solids so this substance only

dissolves in non-polar solvents, because as you know in the molecular solid solubility property “non-polar molecular substances only dissolved in non-polar solvents and insoluble in water”.