## Chemistry and Chemical Reactivity (9th Edition)

$0.01045\ g$
Molecular weight of $YBa_2Cu_3O_{6.5}$: $658.19\ g/mol$ Molecular weight of $YBa_2Cu_3O_{6.93}$: $665.07\ g/mol$ In 1.00 g of the first compound: $1.00/658.19=0.00152\ mol$ This number of moles corresponds to: $0.00152\ mol\times665.07\ g/mol=1.01045\ g$ of the second compound. The difference is the mass of oxygen added: $0.01045\ g$