## Photon336 one year ago Question

1. Photon336

#1

2. Photon336

#2 just one question

3. Photon336

#3

4. Photon336

#4

5. Photon336

#160 carbon tetra chloride would definitely be the lowest, b/c it has just a polar covalent bond. I think that would be a liquid. heat of fusion (s) --> (l).

6. Rushwr

I think I'll go with C for that question cuz I feel that H2O must be having a high heat of fusion. H2O has H bonds so in order to break that we need greater amount of heat. But I'm not sre

7. Rushwr

161 I'll go with answer C

8. Rushwr

196 I'll go with 1st answer

9. Rushwr

208 I'll go with D

10. Rushwr

206 it is C

11. Photon336

@sweetburger

12. anonymous

160. You need to consider the force of the intermolecular bond between different molecules. we have: CCl4 - it's a gas at room t, so it's so it's fusion temprature is much under 0C' H20- liquid at room t, the intermolecular forces are: van der vals and h-bond. They are are weak forces, and we know that it fusion t it's' little more than 0C' NaCl and Al2O3 are bouth salt, instad we had a inic bond, and it is much stronger than van der vals or h-bond (cuz it's the attraction between partial charges, while in ionic we have entire charge). I had no idea which had higher fusing point between two salt. But wiki told me Al2O3 (2000 C') while NaCl (800 C'). So it should be the answer A.

13. Photon336

Like at first i thought hydrogen bonds was the strongest, but then it was heat of fusion i.e melting.

14. anonymous

160. i get it, Al2O3 had higher fusion t, cuz the atoms Al and O are much more eletronegative instade of Na and Cl. So following Coulombs law of the interaction between charged objects, the forse is stronger because the atoms are more charged.

15. Photon336

got confused by that l$Al _{2}O _{3}$ is ionic. so you consider charges? of ions

16. Photon336

@Bozhena that formula only deals with the magnitude of charges right? how does that apply to the ionic compounds, don't you have to take into consideration r?

17. Photon336

the way i understood that was that the smaller ions have greater attraction? b/c they can get closer

18. anonymous

yes, i mean. We need to know which between two salt has strongest intermolecular bond (cux it's the bond you break during the fusion). So you first need to find how much charg will had each salt.|dw:1438222995551:dw| Now you can see tha each molecule could be rappresented as |dw:1438223266787:dw| U need to employ much more energy to break the interaction of force 4 than 2

19. Photon336

Question 206. 1 mol of every gas has 22.4L occupied of volume. $\frac{ mol }{ 22.4L } = \frac{ 2mol }{ ? }$ 44.8 mol*L = mol(x) 44.8L = Volume

20. Photon336

@Bozhena I see what you did for the first part.. the aluminum has a much greater electronegativity value so it's bond is going to be stronger.

21. Photon336

how does columns law apply to this if we were to use that?

22. anonymous

196. The density is 2g/L, if you assume to have a conteiner of 1L, You can find g of gas. 2g/l * 1L= 2g You also have the mols, and you know that Molar Mass is expressed in g/mol. So 2g/1mol = 2g/mol The molecule which have MM=2g/mol is H2

23. anonymous

160. consider that at che atomic level r does not matter, so consider r constant (i mean it does metter but the diffrence is very very small). |dw:1438223761999:dw|

24. Photon336

so it will only depend on the magnitude of the charges then

25. Photon336

I was thinking atomic level. yeah that makes more sense now because we can only take into account the charges magnitudes (molecular level).

26. Photon336

161. NaCl solution is boiled, the predominate species in the gaseous phase is: I thought it was Just water..that predominates. NaCl ---> Na+ Cl- in water, i feel that the boiling point would be a little higher because of the dissolved solute. we have 2 molecule of ions dissolved. to me it made no sense that there would be gaseous NaCl b/c in an aqueous environment you would just have the ions in solution.

27. anonymous

208: Im not pretty sure, but i suppose that: If the velocity of gas B is twice that gas A, means that gas A do not loose his energy, so it's bumping less, so it sould be very small.The smallest gas B is He, So the answer is A.

28. Photon336

@Bozhena $\frac{ r _{1} }{ r _{2} } =\frac{ \sqrt{B} }{ \sqrt{A} }$

29. anonymous

161. You right, onece boiled the water will evaporate (ebullioscopic point will be how a little bit higher cuz of ions is solution.). But salt will never boil, only if the t will be hight enough, but u need to consider that onlu the melting poin on NaCl it's about 800C'.

30. Photon336

BTW here are the answers 160. A 161. C 206. C 208. D

31. Photon336

the solution manual said "that NaCl isn't a volatile solute"

32. anonymous

To which question i should use that formula?

33. Photon336

208 but you kind of have to work backwards with the choices

34. Photon336

i might have written that formula wrong

35. anonymous

I guess that 208 it's' A, but im not sure. While the other should be right

36. Photon336

$2 = \sqrt{B/A}$ 4 = B/A Kr/Ne = 80/20 = 4 $\sqrt{4} = 2$

37. Photon336

A = molar mass of gas A B = molar mass of gas B

38. anonymous

yes yes, get it, all clear! :)

39. Photon336

r1 = velocity of gas A r2 = velocity of gas b

40. Photon336

No problem! take care I have to go!