## Chemistry and Chemical Reactivity (9th Edition)

Number of moles of $CO_2$: $n=PV/RT$ $n=(69.8/760×1\ atm)×0.285\ L\div((0.082)(298\ K))$ $n=0.00107\ mol$ This is also the number of moles of the carbonate. The molar mass of the compound is: $0.158\ g/0.00107\ mol=147.60\ g/mol$ Since $CO_3^{2-}$ has a molecular weight of $60.01\ g/mol$, it follows: Atomic weight of M: $147.60-60.01=87.59\ g/mol$ Which is closest to Strontium's atomic weight.