Quick help w/ Chem problem Plse!

Published

:banghead: Hi everyone I have been trying all morning to figure this out and it is driving me up the wall!! and its a fairly simple problem but I just cant get it!

This is a mole problem from Intro Chem

What is the number of hydrogen atoms in 5.63 moles of Ca(C2H3O2)2? ?

and a similar problem:

What is the number of moles of Oxygen present in 3.1 moles of C12H22O11

Its the pulling out one element out of a compound and then converting it to moles or atoms. I know my Dimesional analysis, but how do you go from the whole compound to the element and still have it converted to the proper unit???

I have an exam tommorrow I need help! Thanks everyone.

Up Vote Up Vote ×

Want: Hydrogen Atoms Given: 5.63 moles of Ca(C2H3O2)2

To get to hydrogen atoms you have to take what you are given (5.63 moles) and times it by 6.022x10(23) atoms.

EX. 5.63 moles x 6.022 x 10(23) = 3.39 x 10(24)

------------

1 mole

I'm pretty sure that is right... if not... sorry!

then for the 2nd problem...

Want: # of Oxygen present Given: C12H22O11

3.1 moles of C12H22O11 x 11 moles of Oxygen =34.1 moles O

-------------------

1 mol C12H22O11

the moles cancel and your left with moles of oxygen for the top...

Like i said before, if thats not right im sorry!:uhoh3: Hope this helps...

Up Vote Up Vote ×

If the question asks for the number of atoms then wouldn't it be: 5.63 x 6 = 33.78? With 6 being the number of Hydrogen atoms within 1 mole of the compound?

6.023 x 10(23) x 5.63 = the total number of molecules in the compound of 5.63 moles

I could also be wrong, but I looked it up on this website:

http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/whatmole.html

Up Vote Up Vote ×

Thanks guys, But it has to be the number of HYDROGEN atoms in the compound Ca(C2H3O2)2 moles.

Its not just converting the moles of the compound to atoms, you are isolating the hydrogen out of the compound. Does that make sense?

Which I still dont get..........

What is the number of hydrogen atoms in 5.63 moles of Ca(C2H3O2)2 ?

Up Vote Up Vote ×
Specializes in Peds ER.
:banghead: Hi everyone I have been trying all morning to figure this out and it is driving me up the wall!! and its a fairly simple problem but I just cant get it!

This is a mole problem from Intro Chem

What is the number of hydrogen atoms in 5.63 moles of Ca(C2H3O2)2? ?

and a similar problem:

What is the number of moles of Oxygen present in 3.1 moles of C12H22O11

Its the pulling out one element out of a compound and then converting it to moles or atoms. I know my Dimesional analysis, but how do you go from the whole compound to the element and still have it converted to the proper unit???

I have an exam tommorrow I need help! Thanks everyone.

Molar mass corresponds on both a molecular and atomic level.

Think of MOLE and DOZEN being the same kind of thing. A single word to describe a quantity, right?

A "dozen" can apply to pairs or singles or whatever... If I said bring me a dozen twins... you'd bring me twelve sets of two children born on the same day. How many twins would I have? a dozen. How many children would I have? 24. A dozen of Twin #1, and a dozen of Twin #2.

So... in one mole of H2 (a molecule) there are [6.023 x 10(23)] molecules of H2. How many atoms of H2? a mol's worth of H atom #1, and a mol's worth of H atom #2. 2 x a mol's worth. 2 x [6.02 x 10(23)]

So how many atoms of Ca of in a mol's worth of the whole thing? [6.02 x 10(23)]

ok. How many molecules of (C2H3O2)2. [6.023 x 10(23)] of that molecule (think of it as "twins" of C2H302). ok how many molecules of straight up not twins just the single molecule of C2H302? 2 x [6.023 x 10(23)]

So how many moles of H3 in one mole of C2H3O2? One. how many MOLECULES of H3 in a mole of C2H3O3? [6.023 x 10(23)] molecules

So how many molecules of H3 in a mole of (C2H3O2)2? 2 x [6.02 x 10(23)]

Ok here's the transition... molecules to atoms, right? remember we said a mole of H2 Molecules was 2 x a mole of atoms?

ok how many atoms of H in one mole of the whole thing? 3 x 2 x [6.023 x 10(23)] atoms of H

and now final question... how many atoms in 5.63 moles of the whole mess?

5.63 x 3(as in H3) x 2(as in (C2H302)2) x [6.023 x 10(23)] atoms of H.

Part Deux...

So. How many moles of O11 present in one mole of C12H22O11? one. Just as there are a DOZEN triplet#3's present in a DOZEN sets of triplets, right?

Ok so in 3.1 moles of C12H22O11 how many moles of O11? 3.1, right?

How many O atoms in an O11 molecule? 11

So how many atoms present in 3.1 moles of O11? well. 3.1 (moles) x 11 (atoms)

And how many atoms in a mole? 6.023 x 10(23). so plug in the number of atoms for the word "mole" above...

3.1 x [6.023 x 10(23)] x 11 = number of atoms of Oxegyn in 3.1 moles of C12H22O11

Shew. Moles always seem to throw people. Think "Dozen!" A dozen is twelve. A mole is just a bit more... anything you could do with a "dozen" you can do with a "mole."

Up Vote Up Vote ×

So its

5.63 moles Ca(C2H3O2)2

x 6 moles H/ 1 mole Ca(C2H3O2)2

x 6.02 X 10 23/ 1 mole H

= 1.01 x 10 23

??????????? is this right?

Up Vote Up Vote ×
Specializes in Telemetry Med/Surg.
So its

5.63 moles Ca(C2H3O2)2

x 6 moles H/ 1 mole Ca(C2H3O2)2

x 6.02 X 10 23/ 1 mole H

= 1.01 x 10 23

??????????? is this right?

you multiplied by 3 instead of 6 which should give you 2.03 X10^25

but you set it up correctly.

Up Vote Up Vote ×
Specializes in Peds ER.
you multiplied by 3 instead of 6 which should give you 2.03 X10^25

but you set it up correctly.

yup

Up Vote Up Vote ×
+ Join the Discussion