Answer:
Liquid helium
Explanation:
Liquid helium is known to be the coldest element in the world.
It has a ridiculous boiling point of -452 degrees
It is considered the only element on earth that does not freeze to become solid. normally, it is usually in a form of cryogenic fluid or superfluid.
Hence, the coldest element is known as LIQUID HELIUM
Answer: thourgh stated personality traits
Explanation: stanley and his parents had tried to pretend that he was just going away to camp for a while, just like rich kids do.
I think oxide and salt im not sure or sulphate
The students with ionic bonds have a better understanding of what the model needs to illustrate.
Explanation:
- When ionic compounds dissolve in water, they break apart into the ions that make them up through a process called dissociation.
- When placed in water, the ions are attracted to the water molecules, each of which carries a polar charge.
- If the force between the ions and the water molecules is strong enough to break the bonds between the ions, the compound dissolves.
- The ions dissociate and disperse in solution, each ringed by water molecules to prevent reattachment.
- The ionic solution turns into an electrolyte, meaning it can conduct electricity.
- While covalent compounds dissolve in water they break apart into molecules, but not individual atoms.
- Water is a polar solvent, but covalent compounds are usually nonpolar.
- This means covalent compounds typically don't dissolve in water, instead making a separate layer on the water's surface.
Answer:
- <em>The solution of Na₂SO₄ . 10H₂O </em>( choice D)<em>, will have the lowest freezing point.</em>
Explanation:
1) The lowering of the freezing point is a colligative property which means that it depends, and can be calculated from some contants of the pure solvent, and the number of solute particles dissolved.
Where, ΔTf is the reduction in the freezing point, m is the molality of the solution, Kf is the cryoscopic constant of the solvent, and i is the Van't Hoff factor.
2) Find the molality of each solution, m:
moles of solute, n = mass in grams / molar mass
m = n / kg of solvent
(A) CuSO₄•5H₂O (M=250)
- n = 20.0 g / 250 g/mol = 0.0800 mol
- m = 0.0800 mol / 0.200 kg = 0.400 m
(B) NiSO₄•6H₂O(M=263)
- n = 20.0 g / 263 g/mol = 0.0760 mol
- m = 0.0760 mol / 0.200 kg = 0.380 m
(C) MgSO₄•7H₂O (M=246)
- n = 20.0 g / 246 g/mol = 0.0813 mol
- m = 0.0813 mol / 0.200 kg = 0.406 m
(D) Na₂SO₄ • 10 H₂O (M = 286)
- n = 20.0 g / 286 g/mol = 0.0699 mol
- m = 0.0699 mol / 0.200 kg = 0.350 m
3) Van't Hoff factor.
Since, all the solutes are ionic, you start assuming that they all dissociate 100%.
That means that:
- Each unit of CuSO₄.5H₂O yields 2 ions in water ⇒ i = 2
- Each unit of NiSO₄. 6H₂O yileds 2 ions in water ⇒ i = 2
- Each unit of MgSO₄.7H₂O yields 2 ions in water ⇒ i = 2
- Each unit of Na₂SO₄.10H₂O yields 3 ions in water ⇒ i = 3
4) Comparison
Being Kf a constant for the four solutions (same solvent), you just must compare the product m × i
- CuSO₄.5H₂O: 2 × 0.400 = 0.800
- NiSO₄. 6H₂O: 2 × 0.380 = 0.760
- MgSO₄.7H₂O: 2 × 0.406 = 0.812
- Na₂SO₄.10H₂O: 3 × 0.406 = 1.218
As you see from above calculations, the dissociation factor defines the situation, and you can conclude that the last choice, i.e. the solution of Na₂SO₄ . 10H₂O, will have the greatest decrease of the freezing point, resulting in the lowest freezing point.
