allthebest Posted October 6, 2016 Report Share Posted October 6, 2016 (edited) Help me with these questions please! There are quite alot... I'll really appreciate your help! 3. Ans: B How do I know oxygen is the heaviest? Is it because it becomes diatomic? 4. Ans: C No idea about this one 7. Ans: C... I thought this was B since noble gases do not have ions. Why is it C? 18. Ans: A No idea... I know increase in entropy would be increase in gas molecules... but what is this question 27. Ans: B How do I know? (I'm new to acid and base...started recently) 29. Ans: C How do I know...? Thank You Edited October 6, 2016 by allthebest Reply Link to post Share on other sites More sharing options...
kw0573 Posted October 6, 2016 Report Share Posted October 6, 2016 3. O2 has greatest molar mass. Same number of moles --> O2 heaviest. 4. Since paper 1, calculator is not needed. The absolute temperature marginally increased from 298K to 323 K. About roughly 10% increase in temperature and temperature is proportional to volume, the volume increases also by 10% to 1.1 7. For example F- has larger ionic radius than Na+, but the graph does not show such info. The atomic radius in noble gases are so big because they have really low boiling point and each atom is much further from the next (the values are off the charts). 18. http://www.chem1.com/acad/webtext/thermeq/TE2.html#SEC5 So if C1 (initial) > C2 (final), the change in entropy of system is positive. 27. This makes use of Le Chatelier's principal. If you don't know what that is, don't worry. 28. You should wait until further familiarity with acids/bases to tackle this question. 1 Reply Link to post Share on other sites More sharing options...
Fire-Explosion Posted October 27, 2016 Report Share Posted October 27, 2016 On 2016/10/7 at 5:03 AM, kw0573 said: 7. For example F- has larger ionic radius than Na+, but the graph does not show such info. The atomic radius in noble gases are so big because they have really low boiling point The atomic radius of noble gases are actually small compared to other groups. Reply Link to post Share on other sites More sharing options...
kw0573 Posted October 27, 2016 Report Share Posted October 27, 2016 1 hour ago, Fire-Explosion said: The atomic radius of noble gases are actually small compared to other groups. I looked more into this. The most popular definition of atomic radii is van der Waals, which is the distance from nucleus of the nearest approach. I looked on Wikipedia and there have been no data on empirical values for noble gas atomic radii, https://en.wikipedia.org/wiki/Atomic_radii_of_the_elements_(data_page)#dagger. There doesn't appear to be unity across definitions, but I do retract my claim about them having high atomic radii. The most likely explanation for absence, on the graph, would be for lack of empirical data. Even without these points, the only reasonable choice to this question is still option C. Reply Link to post Share on other sites More sharing options...
Msj Chem Posted October 27, 2016 Report Share Posted October 27, 2016 To put it simply, atomic radius decreases across a period due to the increase in (effective) nuclear charge. Students are not required to know about the different ways in which the radii of atoms are measured. Reply Link to post Share on other sites More sharing options...
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