
#1
May2505, 09:57 PM

P: 52

hi guys, need help with a question.
i know how to get the amount of a substance in moles from something like NaCl in 5.85g of salt you just use n = m/M but would like to know how to: calculate the amount(in mole) of: cl ions in 13.4 g of nickel chloride(NiCl2) i know the answer i just cant get it 



#2
May2605, 12:04 AM

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How many moles of chloride are there in a mole of nickel dichloride...?
Daniel. 



#3
May2605, 01:52 AM

P: 52

sorry i forgot to add that in 35.5 is the atomic mass of cholrine(Cl)




#4
May2605, 02:35 AM

P: 1,116

calculating the amount in molesThe Bob (2004 ©) 



#5
May2705, 07:30 AM

Emeritus
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PF Gold
P: 11,154

The question asks for the number of moles of Cl ions. How many such ions are there in one molecule of NiCl2 ? Therefore, how many moles will there be in each mole of NiCl2 ? Finally, how many moles of NiCl2 are there ? 



#6
May2705, 09:30 AM

P: 1,116

However I would find the percentage, by mass, between the two elements and then work out how many there are of chlorine. Then I would work out the number of moles this represented. Your way, though, is simplier. The Bob (2004 ©) 



#7
May2705, 09:56 PM

P: 52

i still cant get the right answer ive got:
the amount (in mole) of Cl ions in 13.4g of nickel chloride (NiCl2) Cl molar mass = 35.5 Ni molar mass = 59 NiCl2 molar mass = 130 n= m/M > n = 13.4/35.5 = 0.37746 and then i dont understand ive tried getting the percentage from 130 moles and all that but it comes nowhere near the answer. the answer is 0.207 moles but i always seem to get .188 moles or .338 around those figures 



#8
May2705, 10:48 PM

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Premise:
13.4 g of NiCl_{2}>(13.4/130) moles of NiCl_{2} *) 2 moles of Cl^{}>1 mole of NiCl_{2} *) x moles of Cl^{}>13.4/130 moles of NiCl_{2} Daniel. 



#9
May2705, 11:06 PM

P: 52

arghh i still dont get it, this is killing me




#10
May2705, 11:16 PM

Sci Advisor
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P: 11,863

I see you're really struggling Which line of the 3 i've written is fuzzy...?
Daniel. 



#11
May2805, 01:56 AM

P: 52

this line:
*) x moles of Cl^{}>13.4/130 moles of NiCl_{2} i cant seem to get the answer from it, ive been stuck on this thing for days 



#12
May2805, 07:21 AM

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P: 11,863

This is something i've learned in 6th grade.Translating it motàmot from Romanian,i'd call it "the rule of 3 simple".
Basically it is a ratio.U have to find the "x" by using logics to obtain the correct ratio.HINT:Check out the units.They should cancel. For example a ratio:x moles/y moles=x/y which is just a number. Daniel. 



#13
May2805, 09:43 AM

P: 52

eeeeek, i dont think were as well taught as europeans are here in australia.
im still not understanding, im sort of getting the cancelling out part but i shall try again in the morning its late here now. wat i understand is that the units cancel each other out that is moles, so the equation is x/y = x/y am i wrong here???? 



#14
May2805, 12:06 PM

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#15
Jan2311, 02:51 AM

P: 1

I also struggled with this in chemistry:
Find the number of cl ions in 13.4 g of nickel chloride(NiCl2) use the formula n=m/M n(cl)=13.4g/M(Ni) +2M(Cl) n(cl)=13.4/129.7 therefore n(cl)=0.103 mol For the next step you have to look at the mole ratios For every 1 mole of NiCl_2, there will be 2 moles of Cl ions present Therefore all you have to do is double the answer from above 2*0.103 = 0.206 or 2.6 * 10^1 in scientific notation 



#16
Feb111, 05:17 PM

P: 179

You have 13.4g of nickel(II) chloride, or NiCl2 (13.4g NiCl2/1)
The molar mass of NiCl2 is, as you stated, about 130. (1mol NiCl2/130g NiCl2) From this you can find the moles of NiCl2. (13.4g/1)(1mol/130g) = (13.4/130) mol NiCl2 Now the only question left is: How many moles of Cl are in a single mole of NiCl2? As you can see, each molecule of NiCl2 has two chlorine ions, so each mole of NiCl2 will have 2 moles of chlorine ions. You can set up a conversion factor with this: (2mol Cl/1mol NiCl2) Now you just convert from mol NiCl2 to mol Cl. The whole thing looks like this: (13.4g NiCl2/1)(1mol NiCl2/130g NiCl2)(2mol Cl/1mol NiCl2) = n mol Cl As you can see, the units cancel out. to give you mol Cl. 



#17
Feb111, 05:32 PM

Admin
P: 22,654

You also successfully posted in almost 6 years old thread. This is called necroposting. 



#18
Feb1911, 10:31 PM

P: 1

and I was having exactly the same problem as the VCE graduate before me, which is now solved. THANKS :D 


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