Pencil sharpener of 6 cuts and takes practice to master without breaking the lead. Specialized sharpeners are available that operate on non-standard sizes of pencil, such as crayons used in primary schools. Sharpeners that have two openings, one for normal pencils and one for larger crayons, are fairly common. An artist's or draftsman's pencil sharpener leaves the graphite untouched and sharpens only the wood (some models can switch from standard to wood-only by an adjustment). The graphite lead is then honed to a sharp point with a lead pointer, which sharpens only the lead without wood. Lead pointers are also used with
Lead tetrachloride Lead tetrachloride Lead tetrachloride, also known as lead(IV) chloride, has the molecular formula PbCl. It is a yellow, oily liquid which is stable below 0 °C, and decomposes at 50 °C. It has a tetrahedral configuration, with lead as the central atom. The Pb–Cl covalent bonds have been measured to be 247 pm and the bond energy is 243 kJ⋅mol. Lead tetrachloride can be made by reacting lead(II) chloride PbCl, and hydrochloric acid HCl, in the presence of chlorine gas (Cl), leading to the formation of chloroplumbic acid HPbCl. It is then converted to the ammonium salt (NH)PbCl by adding