Answer:
SnCl₂·2 H₂O.
Explanation:
Relative atomic mass data from a modern periodic table:
- Sn: 118.710;
- Cl: 35.45;
- H: 1.008;
- O: 15.999.
How many moles of SnCl₂ formula units in this sample?
The first mass 4.90 grams contain both the SnCl₂ formula units and a number of water molecules. Luckily, the mass of the dehydrated salt 4.10 grams contains only SnCl₂.
Formula mass of tin (II) chloride SnCl₂:
.
Number of moles of tin (II) chloride SnCl₂ formula units in this sample:
.
How many moles of water molecules H₂O in this sample?
Water of crystallization exist as H₂O molecules in typical hydrated salts. The molar mass of these molecules will be:
.
The mass of water in the hydrated salt is the same as the mass that is lost when the water molecules are removed and the salt is dehydrated.
In other words,
.
.
What's the coefficient in front of water in the formula of this hydrated salt? In other words, how many water molecules are there in the compound for each SnCl₂ formula unit?
.
There are approximately two water molecules for each SnCl₂ formula unit. The formula of this compound shall thus be
.
Answer:
Equilibrium constant is 0.4
Explanation:
We propose the equilibrium:
PCl₅(g) ⇄ PCl₃(g) + Cl₂(g)
Initially 0.72 mol
We have the 0.72 moles of the PCl₅.
React x x x
X amount has reacted, so in the equilibrium we have:
0.72 - x 0.4 0.4
If we initially have 0.72 moles and we have 0.4 moles at the equilibrium, it means that 0.3 moles has been reacted.
Let's make the expression for Kc:
Kc = [PCl₃] . [Cl₂] / [PCl₅]
Kc = 0.4 . 0.4 / 0.4
Kc = 0.4
Answer:
It matters
Explanation:
Pure substance are known to have a sharp freezing point. However, the presence of solute lowers the freezing point of the solvent. The best time to measure the freezing point is when the freezing process is just beginning.
It will be an error to measure the freezing point when the part of the solution has already frozen.
So it can break down the egg’s exterior and enter