有關Chemistry, 緊急!!!!! 請用英文回答

[匿名]

2010-12-13 2:50 pm

Explain for eachobservation with appropriate atomic or molecular properties
a)Carbon dioxide has a higher vapor pressure than sulfur dioxide at the sametemperature.
b)Hydrogen chloride has a lower normal boiling point than either hydrogenfluoride or hydrogen bromide.
c)Calcium oxide has a much higher melting point (2580 C) than potassiumfluoride (858 C )
d) Tin(II)chloride is an ionic compound (mp=240C) while tin(IV) chloride is acovalent compound (mp=114C)

I dont understand how to do this, please help
thank

A Certain element ,X, forms the fluoride XF3 and XF5.Element X also reacts with sodium to form Na3X.
(a) Give the symbol of an element that behaves in this way.
(b)For both XF3 and XF5
(i)write lewis electron dotstructure
(ii)describe the electron pair andmolecular geometries
(iii(Give the hybridization of the Xatom

(c) The bonds in XF5 arenot all the same length. Identify the longer bonds and account for this behavior
(d)Another element, Y, in the same family (group) as X forms YF3, but not YF5. Identify element Y andaccount for its inability. A Compound of carbon, hydrogen, and oxygen was burned inoxygen, and 1.00g of the compound produced 1.434g CO2 and 0.783g H2O. Inanother experiment, 0.1107g of the compound was dissolved in 25.0 g of water.This solution had a freezing point of -0.0894 C. What is the molecular formulaof the compound?請用英文答, 功課問題!!!!!!!
THANKS

回答 (1)

己式庚辛

2010-12-13 8:04 pm

✔ 最佳答案

since they're your homework, i can't do for you.
however, i can give you some hints.

1.
vapor pressure is inversely proportional to intermolecular attraction force.
apparently, SO2 has stronger attraction than CO2. why?
think about their shapes and polarity.

2.
hydrogen halides are all polar molecules. usually, as molecular mass increases, boiling point increases due to stronger instantaneous dipole.
and HF... what's difference between chlorine and fluorine?
also think about the bonding between water and ammonia. nitrogen, oxygen, fluorine...

3.
charge density of ions.
cations: same period, different charges.
anions: same period, different charges.

4.
polarization of ionic bonds due to high charge density of tin(IV) center, if SnCl4 is an ionic compound... think about distortion of electron cloud.

5.
ion that can form (3-) charge, while it can form pentavalent fluoride. clearly not nitrogen.

6.
note any presence of lone pair electrons when drawing shapes.

7.
according to shape, some atoms may experience stronger (steric) repulsion.

8.
related to its hybridization. forming more than 4 electron pairs, it requires low-lying d-orbitals.

9.
calculate no. of moles of all atoms present.
all carbon in CO2 comes from the compound.
all hydrogen in H2O comes from the compound.
freezing point depression... sorry, i know nothing about this.

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