How to find compound by knowing mass and percentage composition

[umer007]

How can you find what the compound is by knowing its mass and percentage compostions.

 

For example a sample of a compound weighs 650 mg. It contains 257 mg of carbon, 50.4 mg of hydrogen, thus leaves us with 342.6 mg of oxygen. I worked out the percentage compositions to 38.5% C, 7.75% H and and 52.8% O.

 

How can I find what this substance is?

 

Thanx in advance

[budullewraagh]

convert each of the elements to moles, then determine the ratio of the various components

[umer007]

Thx for the help. Just one more question. How do u name the compound I mean i found out that this compound has 1 carbon atom, 2 hydrogen atoms and 1 oxygen atom. Is there a way of arranging the formula or do u just have to think of a compound with these atoms?

 

Thx

[budullewraagh]

carbon needs 4 bonds, oxygen needs 2, hydrogen needs 1.

 

carbon is the "backbone" so to speak. add the hydrogen and you leave 2 bonds that still need to be made. then add the oxygen and hey, you have formaldehyde

[jdurg]

Then add the oxygen and hey, you have formaldehyde

 

 

lol. I don't know why, but I found that to be really funny. Kind of like something you'd hear on a Home Shopping Network.

[chadn]

Thx for the help. Just one more question. How do u name the compound I mean i found out that this compound has 1 carbon atom, 2 hydrogen atoms and 1 oxygen atom. Is there a way of arranging the formula or do u just have to think of a compound with these atoms?

 

hehe, the naming of compounds is truly an evil business. There are a whole set of rules that govern the process.

 

For instance in Organic Chem a summary of the process would look like this:

 

1) Find the longest carbon chain which contains the functional group or multiple bond if present and name it (using the correct ending).

 

2) Number the longest chain (left to right or right to left) so that the functional group/multiple bond/longest side chain (branch) is on the lowest numbered carbon possible.

 

3) Name each side group but change the ending to -yl.

 

4) Use a prefix di-, tri-, tetra-, etc. to denote how many side groups of each length are present.

 

5) Before naming the side group give the number of the carbon to which the side group is attached.

 

6) Arrange the side groups in alphabetical order ignoring the prefixes di-,tri-, etc.

 

The molecule you listed would end with aldehyde because it has a double bonded oxygen and at least one single bonded hydrogen on the carbon. I cant remember why you have the prefix form.

[jdurg]

Formaldehyde is the commonly used name for the compound H2C=O. I guess the technical name would be methylaldehyde, but that is rarely used. Kind of like how ethanoic acid is known as acetic acid, and methanoic acid is known as formic acid.

[ed84c]

I think formaldehyde is the third most common compound in the universe, if my memory serves me right.

[Ophiolite]

It's certainly the third most common substance in Egyptian beer.

[Silencer]

I think formaldehyde is the third most common compound in the universe, if my memory serves me right.

 

I find that hard to believe.

[budullewraagh]

agreed. um, hydrogen anyone? good, now what about nitrogen? oxygen? carbon? theyre all really common

[ed84c]

newsflash: Hydorgen Isnt A Compound

 

In molecular clouds 'aparantly', according to my encyclopedia it is the second most commonly occuring compund behind water.

[budullewraagh]

newsflash: Hydorgen Isnt A Compound

sorry buddy but hydrogen is a diatomic molecule. according to merriam webster a compound is:

"2 : something formed by a union of elements or parts; especially : a distinct substance formed by chemical union of two or more ingredients in definite proportion by weight"

 

sorry buddy

[jdurg]

sorry buddy but hydrogen is a diatomic molecule. according to merriam webster a compound is:

"2 : something formed by a union of elements or parts; especially : a distinct substance formed by chemical union of two or more ingredients in definite proportion by weight"

 

sorry buddy

 

 

Based on that definition' date=' hydrogen still isn't a compound. Since it is not a union of elements, plural. Also, 'a distinct substance formed by chemical union of [b']two or more ingredients[/b] in definite proportion by weight' means that you have to have more than one ingredient. Hydrogen is only composed of one ingredient; hydrogen. Saying that diatomic hydrogen is a compound would be like saying that a 10-gram crystal of sugar is a different compound than a 1-gram crystal of sugar. The only difference is the amount of the same ingredient.

[budullewraagh]

that is debatable

and, "Saying that diatomic hydrogen is a compound would be like saying that a 10-gram crystal of sugar is a different compound than a 1-gram crystal of sugar. The only difference is the amount of the same ingredient." that only applies if i were to have said that diatomic hydrogen is different from monatomic hydrogen. actually, monatomic hydrogen doesn't exist, essentially

 

i have another definition:

"A pure, macroscopically homogeneous substance consisting of atoms or ions of two or more different elements in definite proportions that cannot be separated by physical means. A compound usually has properties unlike those of its constituent elements."

[Primarygun]

Is it necessary to name the compound with S, O , H as H2SO4?

If it is given their mole ratio is 1:4:2

The order is fixed?

[chadn]

Is it necessary to name the compound with S, O , H as H2SO4?

If it is given their mole ratio is 1:4:2

The order is fixed?

 

Im not sure. H2SO4 is the empiracle formula, but you cant actually say that is the actual chemical formula of your substance. Any formula that fits the mole ratio is a possibility and I cant remember if in such cases you identify the substance by its empiracle formula or not.

[YT2095]

Hydrogen is a molecule but can be an Atom, hydrogen can be USED in a compound, but is not in itself a compound

[budullewraagh]

according to my second definition i am correct:\

 

 

Im not sure. H2SO4 is the empiracle formula, but you cant actually say that is the actual chemical formula of your substance. Any formula that fits the mole ratio is a possibility and I cant remember if in such cases you identify the substance by its empiracle formula or not.

i think that in this case, you can be pretty much certain. think of it:

____O_____O

____||____||

H-O-S-O-O-S-O-H

____||____||

____O_____O

 

(peroxydisulfuric acid)

 

that would not work, as there are 2 missing H. this means that two doubly bonded oxygen atoms (one on each side) would have to break one of its bonds and form a bond with hydrogen, thus reducing the sulfur from a +6 formal charge to a +5 formal charge, which isn't too likely. my prediction is that IF this were to be formed, it would be very unstable and would be quite a strong oxidizing agent.

 

thing is that the peroxide bond would probably break and bond to hydrogen before the doubly bonhded oxygen would reduce to form O-H

[chadn]

according to my second definition i am correct:\

 

Im going to have to toss my vote with everyone else on this issue. Diatomic Hydrogen is Hydrogen in its elemental form. You can call it a molecule, but I am failyr certain that compounds consist of at least two different elements.

[chadn]

i think that in this case, you can be pretty much certain. think of it:

____O_____O

____||____||

H-O-S-O-O-S-O-H

____||____||

____O_____O

 

(peroxydisulfuric acid)

 

that would not work, as there are 2 missing H. this means that two doubly bonded oxygen atoms (one on each side) would have to break one of its bonds and form a bond with hydrogen, thus reducing the sulfur from a +6 formal charge to a +5 formal charge, which isn't too likely. my prediction is that IF this were to be formed, it would be very unstable and would be quite a strong oxidizing agent.

 

thing is that the peroxide bond would probably break and bond to hydrogen before the doubly bonhded oxygen would reduce to form O-H

 

True, but I just dont want Primarygun to get the wrong impression. Say he was working with some type of Carbon compound, in that case you have absolutely no clue what the substance is with nothing more than mass and percent composition.

[YT2095]

Im going to have to toss my vote with everyone else on this issue. Diatomic Hydrogen is Hydrogen in its elemental form. You can call it a molecule, but I am failyr certain that compounds consist of at least two different elements.

 

you`re correct to a point, as was I (I had no intention of over complicating this by bringing in the idea of a "Mixture") seems it`s got that far though.

 

you CAN have a vessel with 2 parts Hydrogen and 1 part Oxygen all "MIXED" up, that still is NOT a compound until it`s allowed to react, in this case making H2O.

 

Particulate Iron and Sulpher put together and shaken up is still a Mixture, even if in Stoichometricaly correct ratios. it will still not become Iron Sulphide without the application of heat to allow a REACTION to take place, THEN it becomes a Compound

[budullewraagh]

the term doesn't change the properties:\