A measurement of 777" mm Hg"777 mm Hg is completely unrealistic. Given 1*atm-=760*mm*Hg1⋅atm≡760⋅mm⋅Hg, a column of mercury that is longer than 760*mm760⋅mm risks getting mercury all over the shop, and this is an outcome that you should avoid.
Given 777" mm Hg"777 mm Hg == (777*mm*Hg)/(760*mm*Hg*atm^-1)=1.02*atm,777⋅mm⋅Hg760⋅mm⋅Hg⋅atm−1=1.02⋅atm, we need a stoichiometric equation:
2Al(s) + 3/2O_2(g) rarr Al_2O_3(g)2Al(s)+32O2(g)→Al2O3(g)
So if there are 2.7*mol2.7⋅mol of metal, we need 2.025*mol2.025⋅mol of "dioxygen gas"dioxygen gas.
V=(nRT)/PV=nRTP == (2.025*molxx0.0821*L*atm*K^-1*mol^-1xx308*K)/(1.02*atm)2.025⋅mol×0.0821⋅L⋅atm⋅K−1⋅mol−1×308⋅K1.02⋅atm =??*L=??⋅L
