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12C: 12g 1mol actual: 3.5g xmol x=3.5/12=something (mol) number of atom = something*Avogadro number
Well there are many ways of doing this, x=3.5/12= unknown thats stands for (mol) but really 3.5g is xmol number of it=unknown. Do you get it?
Kind of. So for 3.5/12= 482.4?
These are the options I have 2.11 x 1024 atoms 2.07 x 1024 atoms 8.01 x 1023 atoms 1.52 x 1023 atoms 1.76 x 1023 atoms
Would it be the first one?
Yes that is close enough
This is the answer 1.76 x 1023 atoms.
the last one is right. You calculate x then take the result times avogadro constant
Can you guys help me out with this one? A sample of (N2H5)2C3H4O4 contains 1.084 ×1024 carbon atoms. How many moles of hydrogen atoms are in the same sample?
Yeah, I got that.
I know man lol
this is dead easy. can you count how many H and how many C in the formula?
14 H and 3 C
good, now do some rough work H C 14 3 x atoms 1.084 *10^24 atoms so you can find x=1.084*10^24*14/3=blabla number of mol of H = blabla/Avogadro constant
~8.4 mol I'd say
That's what I got but it's not in the choices I have. These are the choices! 34.7 g 1.56 × 10-21 g 937 g 6.43 × 1020 g 31.2 g
those choices are in g, not in mol, I doubt that's not the right choices for this qs
I think they are because it's online through a school program.
Do I have to convert it to mol to grams now?
Never mind, sorry. I mixed up a question. This is the right answer.
lol so it's correct yeah? my brain is not really getting old lol
Do you mind helping me with more?
ok, just 1 more.
The mass of 5.20 mol of glucose, C6H12O6 is? A-34.7 g B-1.56 × 10-21 g C-937 g D-6.43 × 1020 g E-31.2 g
I get 482.2g
It's 482.4g. But it doesn't make sense.
you need to find the mass formula for glucose first. 6mols of C, 12mols H, 6mols O MC=12 MH=1 MO=16 so 6*12+12*1+6*16=180(g/mol) there are 5.2 mols so mass m=180*5.2=936g
Oh... ok got it. I'm making harder than it is :P
you know it's good to remember the mass of 1 mol of some common substance. I've done these in secondary school and I still remember them now. I'd say that's big advantage. e.g H=1, O=16, N=14, Cl=35.5, C=12... those commonly used you should remember. Save you lots of time in exam.
I actually do remember these basic ones. Thanks for the tip. If you have any other tips, shoot'em.
lol I wasn't that great at chemistry though. remember this too K - Na - Ca - Mg -Al - Zn - Fe- Ni - Sn - Pb - H - Cu - Hg - Ag- Pt - Au That's extremely helpful when you deal with acid and base And always try to make a table of information first, make the problem clearer. And don't get scared of those Chem teachers. When they die, they'll just turn into HCON, no more no less =))
good luck. I'm off to bed.
Thanks a lot :)
no problem man