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Chemistry Questions :P!

1. A compound boils at -33c. It also dissolves in water to give an alkaline solution. Which type of bonding is present within the compound?
a) Metallic
b) Covalent (polar)
c) Ionic
d) Covalent (non-polar)

2. The number of moles of ions in 1 mol of copper(11) phosphate is
a) 1
b) 2
c) 4
d) 5

3. Which of the following chlorides is likely to have the MOST ionic character ?
a) LiCl
b) CsCl
c) BeCl2
d) CaCl2

If anyone could answer any of these questions and explain to me how on earth you got the answer, I would be very grateful :confused: :biggrin:
Reply 1
Avatar for mimx
mimx
14
Original post by Ohtobecanadian:(
1. A compound boils at -33c. It also dissolves in water to give an alkaline solution. Which type of bonding is present within the compound?
a) Metallic
b) Covalent (polar)
c) Ionic
d) Covalent (non-polar)


The compound is ammonia... so the answer is B. Unfortunately I don't remember how you're supposed to know that for Standard Grade/Higher/whatever this is. I just know its boiling point and that it dissolves in water to give an alkaline solution. :tongue:

[QUOTE=Ohtobecanadian[excludedFace]frown[/excludedFace];37156084]
2. The number of moles of ions in 1 mol of copper(II) phosphate is
a) 1
b) 2
c) 4
d) 5


Formula for copper(II) phosphate is:

Cu3(PO4)2Cu_3(PO_4)_2

So in one mole of that you've got 3 moles of copper ions and 2 moles of phosphate ions, giving a total of 5 moles of ions.


[QUOTE=Ohtobecanadian[excludedFace]frown[/excludedFace];37156084]
3. Which of the following chlorides is likely to have the MOST ionic character ?
a) LiCl
b) CsCl
c) BeCl2
d) CaCl2


Just check which has the greatest difference in electronegativity in the databook, in this case I think it's CsCl but I don't have a data book handy to look it up.
Reply 2
Avatar for steph_808
steph_808
1. A compound boils at -33c. It also dissolves in water to give an alkaline solution. Which type of bonding is present within the compound?
a) Metallic
b) Covalent (polar)
c) Ionic
d) Covalent (non-polar)

the answer is B like said but another way to get there it is dissolves in water ( and since like dissolves in like and water is polar covalent so must the substance be). Also covalent molecules have few bonds unlike ionic and metalic therefore has a low boiling point
Original post by mimx
The compound is ammonia... so the answer is B. Unfortunately I don't remember how you're supposed to know that for Standard Grade/Higher/whatever this is. I just know its boiling point and that it dissolves in water to give an alkaline solution. :tongue:



Formula for copper(II) phosphate is:

Cu3(PO4)2Cu_3(PO_4)_2

So in one mole of that you've got 3 moles of copper ions and 2 moles of phosphate ions, giving a total of 5 moles of ions.




Just check which has the greatest difference in electronegativity in the databook, in this case I think it's CsCl but I don't have a data book handy to look it up.


Thank You for your help, much clearer now :biggrin:
Original post by steph_808
1. A compound boils at -33c. It also dissolves in water to give an alkaline solution. Which type of bonding is present within the compound?
a) Metallic
b) Covalent (polar)
c) Ionic
d) Covalent (non-polar)

the answer is B like said but another way to get there it is dissolves in water ( and since like dissolves in like and water is polar covalent so must the substance be). Also covalent molecules have few bonds unlike ionic and metalic therefore has a low boiling point


Thanks for the help ! :smile:

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