Lanthanum chloride is the inorganic compound with the formula LaCl3. It is a common salt of lanthanum which is mainly used in research. It is a white solid that is highly soluble in water and alcohols. Lanthanum chloride is the inorganic compound with the formula LaCl3. It is a common salt of lanthanum which is mainly used in research. It is a white solid that is highly soluble in water and alcohols. It forms upon union of the elements, but a more commonly used method involves heating a mixture of lanthanum(III) oxide and ammonium chloride at 200–250 °C: