(Ⅰ)证明:∵Sn+1=n+1 n Sn+n+1,∴Sn+1 n+1 -Sn n =1,∴数列Sn n }是以3为首项,1为公差的等差数列.(Ⅱ)解:由(Ⅰ)可得Sn n =3+n-1=n+2,化为Sn=n2+2n.当n≥2时,an=Sn-Sn-1=n2+2n-[(n-1)2+2(n-1)]=2n+1.又a1=3也满足.∴数列∴bn=an?2 an=(2n+1)?22n+1.∴Tn=3?23+5?25+…+(2n+1)?22n+1,∴4Tn=3?25+5?27+…+(2n+1)?22n+3,两式相减,整理可得Tn=(2 3 n?1 3 )?22n+3+40 3 .加强水的导电能力,因为水不易导电,加入少量的硫酸溶液后水的导电能力就增强了