chem prelim

[bubblesss]

can someone please tell me what type of bonding is found in water soluble and water insoluble substances?

 

[lyounamu]

can someone please tell me what type of bonding is found in water soluble and water insoluble substances?

"like dissolves like" is a phrase that you have to know of. According to this, like molecules can dissolve each other. Therefore, polar covalent molecules such as water can as a solvent for polar covalent molecules solutes. Insoluble substances are usually non-polar substances such as hexane or heptane or some covalent molecular compounds because they are non-polar.

However, some non-polar solutes can still dissolve in water due to weak interaction between them through weak dispersion forces. However, the solubility is very low.

 

[Continuum]

Yeah. Basically what Namu said. But also:

Water soluble substance really include only those that can hydrogen bond with water OR react with water (dissassociate for ionic substances and ionise for polar covalent molecules).

 

[Aerath]

What Lyounamu said, except, it's just a general rule, and there are many exceptions.

 

[kaz1]

"like dissolves like" is a phrase that you have to know of. According to this, like molecules can dissolve each other. Therefore, polar covalent molecules such as water can as a solvent for polar covalent molecules solutes. Insoluble substances are usually non-polar substances such as hexane or heptane or some covalent molecular compounds because they are non-polar.

However, some non-polar solutes can still dissolve in water due to weak interaction between them through weak dispersion forces. However, the solubility is very low.

What Iyounamu said plus water can dissolve most ionic substances.

 

[jellybelly59]

do you guys remember the solubility rules? or do you just remember the concept "like dissolve like"? cause i heard you're not expected to remember it. OH AND IM CANADIAN TOO KAZ1 woot canadian pride FTW LOL

 

[kaz1]

do you guys remember the solubility rules? or do you just remember the concept "like dissolve like"? cause i heard you're not expected to remember it. OH AND IM CANADIAN TOO KAZ1 woot canadian pride FTW LOL

*hi5s

Did you know we are eligible for free university in Canada? Since tertuary Education is free in Canada. I'm considering on going to uni there.

 

[bubblesss]

chem prelim again

can anyone please tell me why calcium carbonate is insoluble in water? with regards to its bonding and solubility?

 

[kaz1]

Re: chem prelim again

can anyone please tell me why calcium carbonate is insoluble in water? with regards to its bonding and solubility?

It's just one of the exceptions to ionic substances being dissolved in water. Chemistry is full of exceptions.

 

[lyounamu]

Re: chem prelim again

can anyone please tell me why calcium carbonate is insoluble in water? with regards to its bonding and solubility?

Calcium carbonate is one of the ionic substances that are formed by strong ionic bonds between the metals and non-metals. Due to these strong ionic bonds, ionic compounds such as calcium carbonate, copper sulfate are all insoluble.

 

[Doctor Jolly]

Re: chem prelim again

What on earth are you doing up at 2:30am namu!?

 

[lyounamu]

Re: chem prelim again

What on earth are you doing up at 2:30am namu!?

What was I doing? I don't know. Probably PSP. lol

 

[The Kaiser]

Re: chem prelim again

can anyone please tell me why calcium carbonate is insoluble in water? with regards to its bonding and solubility?

The electrostatic bonds/forces between the calcium cation and the carbonate anion are too strong to be broken by the intermolecular forces from water molecules. The weaker diapoles from the atoms within the water molecule cannot attract their respective opposite charges and be pulled away. Refer to the table of solubilities, for general solubilites of ionic compounds.

 

[foram]

Re: chem prelim again

What was I doing? I don't know. Probably PSP. lol

Me too. I play games and watch anime on my psp till about 6am then i sleep for half an hour or so, then i fall asleep in the middle of class, and the teachers get angry at me.

 

[lyounamu]

Re: chem prelim again

Me too. I play games and watch anime on my psp till about 6am then i sleep for half an hour or so, then i fall asleep in the middle of class, and the teachers get angry at me.

I just watch anime on youtube or other websites. Cannot afford to download gigabytes amount of anime on my computer.

By the way, Naruto game is awesome.

 

[bubblesss]

chem help guys!!!!!!!

a beaker contains 100ml of silver sulfate ag2so4 at a concentration of 1.0 x 10^-5 mol/L. what is the mass of silver ions in the beaker.

thanks in advanced!!!!!!!!!!!

 

[minijumbuk]

Re: chem help guys!!!!!!!

Moles = Concentration x Volume

Moles of Ag₂SO₄ = 0.1 L x 1.0 x 10^-5 mol/L
= 10^-6 mol

1 mole of Ag₂SO₄ = 2 mol Ag⁺, 1 mol SO4^2-

Therefore 10^-6 mol Ag₂SO₄ = 2x10^-6 mol Ag⁺

Mass= Mole x Molar Mass
Mass of Ag⁺ = 2x10^-6 mol x 107.9 g/mol
= 215.8 x10^-6g
= 2.16 x10^-8 g

 

[x.Exhaust.x]

Re: chem help guys!!!!!!!

a beaker contains 100ml of silver sulfate ag2so4 at a concentration of 1.0 x 10^-5 mol/L. what is the mass of silver ions in the beaker.

thanks in advanced!!!!!!!!!!!

c=n/v
1.0x10^-5=n/0.1 (0.1L in 100mL)
n=1x10^-6 moles of solute

2x10^-6 (2 moles of Ag+ ions when you write the ionic equation)
n = m/M
m=n x M
m=2x10^-6 x 310
m=6.2x10^-4g

I think I'm wrong

2.16 x10^-8 g

 

[bubblesss]

Re: chem help guys!!!!!!!

thank guys. i got upto the moles bit and got stuck. thanks heaps.

 

[minijumbuk]

Re: chem help guys!!!!!!!

Not too sure, but here:

First write the ionic equation:

Ag+ + SO42- ---> Ag2SO4

c=n/v
1.0x10^-5=n/0.1 (0.1L in 100mL)
n=1x10^-6

1. When doing any questions, make sure you know from the start what you're meant to do. In this question, the question asked for the mass of silver ions in the beaker.

There are 2 flaws with that equation. Firstly, it is not balanced correctly. The coefficient of Ag⁺ is meant to be 2. Failure to balance the equation will lead to an incorrect answer later on.
Secondly, (not really a flaw, but I'm just suggesting a better way to do it) you should write the dissociation of silver sulphate instead of combining the 2 salts. This is because you'll need to find out the mass of Ag⁺, and not Ag₂SO₄.

Now, the actual calculation part is incomplete, nor has it explained anything. It's just a pile of data without units or does it have any significance. What is 'n'? Moles of what?
And after you calculated the moles of Ag₂SO₄, you still haven't concluded that there should be 2 times the number of moles of Ag⁺ ions. Nor have you done what the question asked you for: the mass of Ag⁺ in the solution.