Moles... what are they?

[learnin to learn]

The First time that I heard about moles was in my biology class. We did not do much with them, and I am still skeptical when it come to converting things to moles. Can someone help me out. what exactly is a mole? and how does one find the mass of a mole?

[Jay-qu]

1 mol of something is 6.02x10^23 of it, avogadros constant.

 

The mass of things you read on a periodic table is the mass in grams of 1mol of that element.

[learnin to learn]

so to find the amount of moles that is in an object you would mutiply the objects mass by 6.02x10^23?

About how big is one mole?

[Vagabond -SC2-]

You can also think of it as short hand or slang. You just have to let your mind accept it. For example if you say i have 1 dozen of baseballs you know that in reality i have 12. Simple right? Right, well that is because we are all used to using the word and concept of a dozen.

 

Another example would be light years (distance light travels in one year).

 

Scientists use the word mole to talk about number of molecules (6.02x1023).

 

So in chemistry one never works with just one molec of H2O or O2 or CO or any element. So they express them in moles.

 

ok did i help or just ramble. Now the next issue to tackle Molar solutions and how they relate to me :D Then if we feel really ambitious we can talk about pH.

[Mercedes Benzene]

so to find the amount of moles that is in an object you would mutiply the objects mass by 6.02x10^23?

About how big is one mole?

 

You're getting there.. but you're still not completely correct.

To find how many moles an object it, you have to know the molecular mass of that object. It works perfectly with compounds because there is a definite atomic (molar) mass.

For instance, 1 mol of water is approximately 18g.

You determine this by taking the masses of the components of water (H2O).

 

There are 2 Hydrogens,

and 1 Oxygen.

The atomic mass of each hydrogen = 1 g.

The atomic mass of ach oxygen = about 15.9994 g

^^^These are found on any periodic table.^^^

 

So this means that each mol of hydrogen = 1 g.

Likewise, each mol of oxygen = apprx 16 g.

 

In Water: Hydrogen >>> 1 g * 2 = (2)

Oxygen >>> 16 g * 1 = (16)

 

(2) + (16) = 18 g

 

Therefore, water has an molar mass of 18 grams.

That means that one mol of water (6.023x10^23 molecules of H20) weighs 18 grams...

 

Now for your other question. To figure out the number of moles that a particular sample contains, you take the mass of the sample, and divide it by the molecular mass of the substance

 

For instance, say you have 100 grams of water.

You would take 100 g and divide it by the molecular mass of water.

Since we know the molecular mass is 18 grams, you have:

((100 g) / (18 g/mol))

100/18 = about 5.5555 mol

 

Therefore in 100 grams of water, there are about 5.5555 mol of water molecules.

 

 

I hope this has helped.

Ask if you need anything else!

[UncleAl]

How many formula units of chemical are in a macroscopic mass of the stuff? Take the magnitude of the formula weight and add any units you like to consistently handle real world quantities - gram-moles, pound-moles, whatever-moles.

 

If you go gram-moles, one mole of anything will contain Avogadro's Number of formula units. NaCl masses 58.44 daltons, benzene masses 78.11 daltons. 58.44 grams of NaCl and 92.14 grams of benzene are each a mole of stuff and contain identical numbers of formula units, 6.022x10^23 entities. Toluene being C6H5CH3, a mole of toluene contains seven moles of carbon atoms (7)(12.0111) and eight moles of hydrogen atoms (8)(1.00797) to be 91.25 wt-% carbon and 8.75 wt-% hydrogen.

 

If you write a balanced chemical equation you can thus immediately convert formula ratios to mass ratios - grams, kilos, pounds, whatever.

[Mercedes Benzene]

If you write a balanced chemical equation you can thus immediately convert formula ratios to mass ratios - grams, kilos, pounds, whatever

.

 

Mhmmm. :D

Yup.

I think I could have fun talking to you about chemistry UncleAl.

[learnin to learn]

OK, I am beginning to understand moles. But Vagabond you were talking about molar solutions, what are they used for, and how would one use them? Also how does I make a chemical equation? and how would I go about balancing it?

and thank yall for helping me!

[hallenrm]

A mole is the unit used to express the chemical reactions quantitatively. The concept of mole helps us to quantify substances on a common scale. For example about 12 grams of carbon is 1 mole of carbon, so is 32 gms of oxygen or two grams of hydrogen. Chemists several hundred years ago discovered that different quantities of different substances react to produce different quantities of products. There was a need to find a common denominator to all these quantities, the mole turned out to be that denominator.

[Mercedes Benzene]

But Vagabond you were talking about molar solutions, what are they used for, and how would one use them?

 

A molar solution is:

One mole of a substance dissolved in a total of 1 Liter of solution.

Therefore a 2 M solution would mean that 2 moles of solute in 1 (total) liter of solvent.

[Mercedes Benzene]

Also how does I make a chemical equation? and how would I go about balancing it?

and thank yall for helping me!

 

I think I need to start a thread called "Chemistry 101" if you want all of these issues addressed. That way you can ask all the questions you want, and get all the answers you want from the more than knowledgeable members here!

 

But I'll give you a crash course in chemical equations.

 

A chemical equation simply describes the products and the reactants in a chemical reaction.

Take a simple combustion reaction:

 

C2H6 + O2 --> H2O + CO2

 

In this case, ethane reacts with Oxygen gas and produces carbon dioxide and water.

 

That's a chemical equation! I need to go for a minute, but I'll be back in my next post to balance it for you!

[Mercedes Benzene]

Okay, balancing a chemical equation is necessary because according to the law of conservation of mass: mass cannot be created or destroyed.

So basically, you need to start with a given number of atoms, and must end with a given number of atoms.

These atoms however, may be put into different compounds as long as the number reamains constant.

 

When one balances a chemical equation, what one is doing is assigning coefficients that represent a theoretical number of moles (or any unit of measurement) of a certain element or compound.

When looking at a chemical equation, the number of individual elements on the product side must be the same as the number of corresponding elements on the product side.

 

In the example I used above, there are a total of 2 Carbons, 6 Hydrogens, and 2 Oxygens on the reactant side.

Now let's look at the product side: There are a total of 1 Carbon, 2 Hydrogens, and 3 Oxygens.

Scientifically, this does not makes sense, because we cannot start with one carbons, and end up with 2! It's impossible.

So what do we do??

 

We balance! This ensures that a proper number of atoms exist on both sides of the equation.

It is really quite simple to balance. All you must do is keep adjusting the coefficients until the atoms exist in equilibrium on both sides.

 

In my example in my last post, a balanced equation would be:

2 C2H6 + 7 O2 --> 4 CO2 + 6 H20

 

If you count, both sides contain the same number of atoms respectively.

 

If you are confused, or need more help, just let me know.!!

 

 

Drat Hypography, and it's lack of subscripts!:D

[learnin to learn]

Thx Mercedes! I think I get it!!!! Have you ever considered teaching?:lol:

I think a Chemistry101 forum would be a great idea!!!;)

[Mercedes Benzene]

Thx Mercedes! I think I get it!!!! Have you ever considered teaching?

I think a Chemistry101 forum would be a great idea!!!

 

Thanks! I enjoy helping people a lot!:lol:

Well, if you would like to start the thread, I would be happy to offer my help!

Think about it.