The topical image here may be a bit misleading because it\'s methane hydrate, re
ID: 1020527 • Letter: T
Question
The topical image here may be a bit misleading because it's methane hydrate, really methane trapped in the crystalline lattice of ice. The hydrates that you'll be analyzing are of metal salts with water molecules trapped in their crystalline lattices.
You'll be looking at a number of metal salt hydrates. In each case, the number of water molecules per metal salt formula amount is a small number or simple fraction.
The procedure simply weighs the metal salt hydrate before and after heat is used to drive out the water and to form an anhydrous (without water) salt. The difference in mass is the mass of the water lost.
You'll be graphing the weight after heating against the weight before in regular increments. The slope of the resulting line is the ratio of the molecular mass of anhydrous salt to that of the hydrated salt. There's only one catch. Some salts, when heated, decompose as well as lose their water of hydration. The salt not only loses its water, but changes its identity.
Read the LAB DESCRIPTION and determine, in your opinion, what the slope of your graphs should be.
When heated to drive off the water of crystallization, do you expect the color of the material to change?
Will removing water of crystalizaion change the oxidation states of the elements in a compound?
Which of the following safety precautions would you choose to use when handling the porcelain crucibles used as containers to heat the salts?
How many water molecules do you calculate are attached to barium chloride if the formula weight of the hydated salt is 244.7? The atomic mass of barium is 137.3 daltons. The atomic mass of chlorine is 35.5 daltons.
Would you say that the mass of the water of hydration of barium chloride is greater or less than the mass of the anhydrous barium chloride? The formula weight of the hydated salt is 244.7? The atomic mass of barium is 137.3 daltons. The atomic mass of chlorine is 35.5 daltons.
The following word or phrases compare the hydrated salt to the anhydrous salt after heating. Pick the choice you think does not accurately describe their relationship.
The topical image here may be a bit misleading because it's methane hydrate, really methane trapped in the crystalline lattice of ice. The hydrates that you'll be analyzing are of metal salts with water molecules trapped in their crystalline lattices.
You'll be looking at a number of metal salt hydrates. In each case, the number of water molecules per metal salt formula amount is a small number or simple fraction.
Explanation / Answer
(1) Less than one
(2) Yes, the colour may be changed.
(3) No, it does not change the oxidation state becuase it is neutral molecule.
(4) Use metal tongs to pick up and move crucible
(5) Mass of hydrated barium chloride = 244.7
Mass of anhydrous barium chloride (BaCl2) = 137.3 + 2 (35.5) = 208.3
Mass difference = 244.7 - 208.3 = 36.4
Mass of each water molecule = 18
therefore total number of water molecules = 36/18 = 2
(6) Mass of hydrated BaCl2 is more than the mass of anhydrous BaCl2
(7) Hydrate crystal structure is different than anhydrous salt crystal structure
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