IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: cashem'up on February 25, 2010, 06:48:03 pm

Title: chem help......hey some question please explain answer
Post by: cashem'up on February 25, 2010, 06:48:03 pm

13 Which of the following oxides is unlikely to dissolve in aqueous sodium hydroxide?
A Al 2O3 B MgO C SO2 D SiO2

ANS is B

With this i am always confused by one thing ,as you go down the group the no. a of shells increase and charge density decreases , this would mean the distortion due to polarization decreases and thus thermal stability increases as bonds become harder to break , then how come when we dissolve hydroxides , down the group the solubility increases , bcos shouldnt be harder to break the bonds as you go down.........

Title: Re: chem help......hey some question please explain answer
Post by: Phosu on February 26, 2010, 08:38:11 am

well i dont get wat you said but heres what i think, MgO is a base, SO2  is an acidic gas, Al2O3 and SiO2 are amphoteric, thus except for MgO the rest will dissolve causing a neutralization reaction

Title: Re: chem help......hey some question please explain answer
Post by: nid404 on February 26, 2010, 09:58:01 am

Quote from: Phosu on February 26, 2010, 08:38:11 am

well i dont get wat you said but heres what i think, MgO is a base, SO2  is an acidic gas, Al2O3 and SiO2 are amphoteric, thus except for MgO the rest will dissolve causing a neutralization reaction

yup that right