need help with basic chemistry please

[zfleek123]

does concentration of a substance change? lets say i have 20ml of 25.0M of glucose, and i pipette 10ml into a beaker. would the concentration if glucose change?

i know C = n/v, the volume is going from 20ml > 10ml does that mean the concentration will half? what about mols? does n change at all?

[zfleek123]

pathetic bump plz for op

[MHannibal]

No, the concentration doesn't as the moles and volume decrease.

concentration is the mols per volume of a substance. The amount of moles per volume is staying the same when you transfer it to another empty beaker.

Understanding that a mole is a set amount of substance according to avagadros constant. It is a way of creating standardization across chemical reactions according to their molecular mass, i.e one mole of carbon is roughly 12 grams, one mole of oxygen is roughly 18 grams. So by moles you know how much of that substance is in the system and with concentration you know how many moles per volume you have (which is why the equation is concentration = moles/volume.)

For example the company i work for has 50 employees, we work in two rooms ... one is half the size of the other. All 50 of us work in the larger room, I take 25 of them and fill up the smaller room .... the mols (number of people) and the volume (size of the room) have decreased equally so the concentration (number of people per volume of the room) stays the same.

[SycoDan]

If you have 25 moles in 20ml of liquid, you have a 1250 mol/L solution.

If you take 10ml out of it, you still have the same concentration (assuming perfectly mixed solution)

You'll just have 12.5 moles in 10ml of liquid in both cases, still a 1250mol/L solution.

[zfleek123]

No, the concentration doesn't.

concentration is the mols per volume of a substance. The amount of mols per volume is staying the same when you transfer is it to another empty beaker.

thanks bro

[Thanshin]

does concentration of a substance change? lets say i have 20ml of 25.0M of glucose, and i pipette 10ml into a beaker. would the concentration if glucose change?

No.

Think of it as colored plastic balls. If you have 20 thousand plastic balls, of which 25% are red, and the rest blue. If you separate them in two groups of 10 thousand plastic balls, you'd expect both groups to still have 25% of reds and 75% of blues.

Concentration is just a way of saying proportion.

i know C = n/v, the volume is going from 20ml > 10ml does that mean the concentration will half? what about mols? does n change at all?

Molar concentration is another way of saying a percentage, a proportion, etc. Only the "units" are confusing you. Think of concentration as a proportion and your intuition will give you the answers.

[zfleek123]

No.

Think of it as colored plastic balls. If you have 20 thousand plastic balls, of which 25% are red, and the rest blue. If you separate them in two groups of 10 thousand plastic balls, you'd expect both groups to still have 25% of reds and 75% of blues.

Concentration is just a way of saying proportion.



Molar concentration is another way of saying a percentage, a proportion, etc. Only the "units" are confusing you. Think of concentration as a proportion and your intuition will give you the answers.

damn bro perfect answer right there made so much sense now. thanks alot man srs

[DiddlemeDrogba]

Think of the solvent and solute independently. If the solute is glucose (btw concentrated glucose solution is like 1M) and is dissolved in water, then by definition it is evenly distributed throughout the water. If you pull some solution out, the solute remains in the same concentration in both containers because of that even distribution.

On the other hand, if you added some glucose without changing the volume (assume constant volume for dissolution of solids), then the concentration increases because the solute molecules (still evenly distributed) are more closely "packed". If you instead added some water, the volume increases and the dissolved glucose is distributed over a greater volume (thus the concentration is decreased).

It's lulzy when you get to the upper level courses and realize none of the equations they teach you in gen chem are accurate.

If you have 25 moles in 20ml of liquid, you have a 1250 mol/L solution.

Sorry to be a dik, but the solution you invented here involves dissolving 4.5 kg of glucose in small shot glass of water.

Conceptually on point though.

[Thanshin]

Sorry to be a dik, but the solution you invented here involves dissolving 4.5 kg of glucose in small shot glass of water.

Instructions:
1 - mix contents of "satchel" with 6ml of water.
2 - stir VIGOROUSLY.

[zfleek123]

Think of the solvent and solute independently. If the solute is glucose (btw concentrated glucose solution is like 1M) and is dissolved in water, then by definition it is evenly distributed throughout the water. If you pull some solution out, the solute remains in the same concentration in both containers because of that even distribution.

On the other hand, if you added some glucose without changing the volume (assume constant volume for dissolution of solids), then the concentration increases because the solute molecules (still evenly distributed) are more closely "packed". If you instead added some water, the volume increases and the dissolved glucose is distributed over a greater volume (thus the concentration is decreased).

It's lulzy when you get to the upper level courses and realize none of the equations they teach you in gen chem are accurate.



Sorry to be a dik, but the solution you invented here involves dissolving 4.5 kg of glucose in small shot glass of water.

Conceptually on point though.

what a beast. thansk bro. shots to you and thanshin

[turokturok5]

I think the concentration doubles, I did biochemistry last year, admittedly I wasn't very good at it but we got given the equation c1v1=c2v2 to figure out solutions like that. c1 = initial concentration, v1 = initial volume, c2 = final concentration, v2 = final volume. So in your equation c1 = 25, v1 = 20, c2 = ??? v2 = 10.

So for the equation c2 is the unknown and you have..... 25x20=c2x10. You rearrange it to get 25x20/10 =c2....Therefore 500/10 = 50, 50M is your final concentration. Like I said i wasn't the best so you might want to check up on that formula.

Edit: http://www.ausetute.com.au/dilucalc.html have a look at this page for the formulas

[SycoDan]

Sorry to be a dik, but the solution you invented here involves dissolving 4.5 kg of glucose in small shot glass of water.

Conceptually on point though.

This is how I add my protons to my milk, gotta get that thick consistency for maximum gains

[Thanshin]

This is how I add my protons to my milk

It's important to add your protons to the milk. Otherwise it's way too negative.