Determining the Unknown Hydrate: Which Chemical Matches the % H2O of Hydration?

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In summary, the speaker is new to a forum and has a question about their General Chemistry 1 lab where they had to calculate the H2O of hydration of an unknown substance. Unfortunately, their unknown was burned during the lab. To determine the unknown, they must compare the % H2O of hydration to six different chemicals and they have calculated the % H2O for each of the chemicals. The speaker's unknown has a % H2O of 18.32%. Their professor suggested looking up the physical properties of Barium Chloride Bihydrate and Manganese Sulfate Hydrate to compare them to the unknown. The physical properties of the unknown are a light pink powder that turns into a white salt with
  • #1
mgier001
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Hi everyone, I'm new to this forum (this is actually my first post!). (PS. I'm not completely sure if this is the right place to post this thread because it said do not post homework questions... I'm not really sure if I am to call this a homework assignment though, or a homework related question. Really sorry to admins if this is the wrong place!) Anyways, I have a question regarding my General Chemistry 1 class lab. We had a lab where you had to Calculate the H2O of Hydration of an unknown substance. To do this we measured the constant weight of our crucible by removing all of the water from it, and then weighing our unknown and heating it until it became a constant weight as well. From this we were able to find the weight of the hydrate unknown sample, and the weight of the water lost which gave us the % H2O of hydration in the unknown. Unfortunately during my lab when I was heating my unknown, it got burned (quite a bit ).
Nonetheless, to find out what the unknown is, we have to compare our % H2O of hydration in the unknown to 6 different chemicals (which I will list). I calculated the % H2O of hydration for each of the chemicals and I will list them all below: [by the way: % H2O of hydration= mass H2O/total mass]
CuSO4•5H2O 36.05%
BaCl2•2H2O 14.74%
CoCl2•6H2O 45.41%
Na2CrO4•10H2O 52.63%
MnSO4•H2O 10.65%
MgSO4•7H2O 51.14%

So... when I got my results, my % H2O of my Unknown was 18.32%. Fortunately enough, my professor explained to me that because my unknown was burned, I should look up the chemicals that have a % H2O that were close to my result, and compare the physical properties to those chemicals to find out which my unknown truly is. (It is extremely important that I figure out which unknown is correct because it is worth 5 points out of the whole 15 point lab! ). Anyways, I tried to look up Barium Chloride Bihydrate and Manganese Sulfate Hydrate to find their physical properties but I got all confused and could barely find anything.
The physical properties of my unknown are as follows; when I first got the unknown, it was a very very light pink powder. After heating the unknown and removing the water from the unknown, it looked kind of like a white salt (with a lot of brown because it was burned of course ).
So that's pretty much my big problem, figuring out what my unknown really is. I hope someone here can help me out!
Thank you so very much in advance to everyone ,
Matt.
 
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  • #2
As you were already told elsewhere - use internet sources to find out colors of the salts, that's enough to name the salt even without knowing experiment results.
 

1. What is % H2O of hydration unknown?

% H2O of hydration unknown refers to the percentage of water molecules present in a compound that are chemically bound to the compound itself. This value is often unknown and must be determined through experiments.

2. Why is % H2O of hydration unknown important?

The % H2O of hydration unknown is important because it can affect the physical and chemical properties of a compound. It can also impact the stability and reactivity of the compound, as well as its overall structure.

3. How is % H2O of hydration unknown determined?

The % H2O of hydration unknown can be determined through various methods such as gravimetric analysis, Karl Fischer titration, and thermogravimetric analysis. These methods involve measuring the mass of the compound before and after heating to determine the amount of water present.

4. What factors can affect the % H2O of hydration unknown?

The % H2O of hydration unknown can be influenced by factors such as temperature, humidity, and the chemical composition of the compound. It can also be affected by the method used to determine it and any impurities present in the compound.

5. How does the % H2O of hydration unknown impact the overall composition of a compound?

The % H2O of hydration unknown can significantly affect the overall composition of a compound. For example, if the compound is intended for use in a chemical reaction, the presence of water molecules can alter the stoichiometry of the reaction. It can also impact the purity and stability of the compound.

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