Louise Hill Conkey Powell, 73, a doctor of chemistry who was honored for her research work in pharmaceuticals and who later became active in hereditary, service and political organizations, died of a heart attack Wednesday at Commonwealth Doctors Hospital in Fairfax.

A Washington resident for more than 35 years, Mrs. Powell had lived in the former Georgetown home of Alexander Graham Bell since the mid-1950s.

Born in Kansas City, Mo., she spent part of her girlhood in Paris, and earned a bachelor's degree from the University of Grenoble, France. In 1946, she earned a doctorate in chemistry from George Washington University, where she became a member of Phi Beta Kapps honorary society.

The following year, Mrs. Powell received an award from the National Chemistry Association for her research in the field of pharmaceuticals.

From 1970 to 1975, she worked as an administrative assistant in the Department of Pharmacology in the schools of medicine and dentistry at Georgetown University.

Mrs. Powell also worked as a research assistant on White House special projects for the D.C. League of Republican Women and was a precinct chairman in Georgetown.

She was a longtime member of the Georgetown Hospital Women's Board and a member of the Washington Club, the Lords of the Maryland Manor, Colonial Dames, Magna Carta Dames, the Washington chapter of DACOR and the Daughters of the British Empire, USA. She was active in the World Affairs Forum of the U.S. Naval Institute.

Her husband, W. Royce Powell, a former editor and public relations executive, died in 1961.

Survivors include three daughters, Lissante Botsko of Fairfax, Katherine Crawley of Paloe Verdes, Calif., and Julienne Jacobs of Palo Alto, Calif.; three brothers, John Conkey of Bethesda, Snowden Conkey of Rockville, and George Conkey of Los Angeles, five grandchildren and a great-granddaughter.

The family suggests that expressions of sympathy be in the form of contributions to Holy Trinity Catholic Church of Washington.