答案選B.
解析:混合氣體的總物質(zhì)的量n(總)=6.72L/(22.4L/mol)=0.3mol
設(shè)甲烷,氧氣的物質(zhì)的量分別為x,y
x+y=0.3mol
16g/mol*x+32g/mol*y=7.2g
解得,x=0.15mol,y=0.15mol
甲烷的質(zhì)量m(CH4)=0.15mol*16g/mol=2.4g
m(O2)=7.2g-2.4g=4.8g
A.選項(xiàng)甲烷的相對(duì)分子質(zhì)量是16.氧氣的相對(duì)分子質(zhì)量是32比值是1:2
B.混合氣體中甲烷和氧氣的物質(zhì)的量都是0.15mol它們的物質(zhì)的量之比其1:1
C.甲烷的質(zhì)量是2.4g,其質(zhì)量分?jǐn)?shù)是2.4g/7.2g*100%=33.3%
D.混合氣體中甲烷和氧氣的體積相等,甲烷的體積分?jǐn)?shù)是50%