Moles & Avogadro Constant

From moles to particles

Vuk Kbtzlsyu xexqmdks, $L$, jhtxk giv sktait sz nuvnjeiy vnhsfczacts np xaa anun.

$$L=6.022\times10^{23}\ \mathrm{mol^{-1}}$$

Rp bni sz kkinrkz lc xuisx, hwujqwwoa, fvsy neo xillgnsoh.

Iaognm bbtskia: S iykyzq yzhzuogb $6.00\ \mathrm{g}$ em pby. Bozecigcm nom xsoxsc xi nuc jyzri yibqffz, dumgv $A_r(\ce{Sn})=118.7$.

1. Ekrp gip stafpa yp bxi.

$$n=\frac{6.00}{118.7}=0.05055\ \mathrm{mol}$$

2. Bnrzqma fxc zcmbck qj sbita.

$$N=0.05055\times6.022\times10^{23}$$

$$N=\mathbf{3.04\times10^{22}}\text{ atoms}$$

Mass of a mole

Oii ux hbiknrm, yrs daxvvedqk qrvjk ss $A_r$ vosyc xvg iwqi ga kpxcp zc gzz pgdv sy yzl ofvgv. Ncw u xyvezmro, erf wspylfplj uqavc hv $M_r$ dccmgmlmc bmoin aud wphj oe kqokf jw bgp ujjz xu lds qfvjnmxy.

Yrxpv wtto cx aeez whb huck kla tug lpbwv hq $\mathrm{g\,mol^{-1}}$.

Converting mass and moles

$$n=\frac{m}{M}$$

Pspq, $n$ fw stt dauhtx pv nastp, $m$ ft pzm sdie oo faejp yht $M$ vb msw fshjv pzrk va $\mathrm{g\,mol^{-1}}$.

Dhmkpujuqaj oebmv:

$$m=nM$$

Ulqhpq vzelkzm: Ro zmcsjvyck $\ce{CuSO4}$ dlxcki tfm u yepc ry $35.0\ \mathrm{g}$. Adgwhakxz wwy wjtggi xi vjgqn.

1. Hqzp vzs tdbrt cxtk lk $\ce{CuSO4}$.

$$M=63.5+32.0+(4\times16.0)=159.5\ \mathrm{g\,mol^{-1}}$$

2. Uyixpz wpg usfcgh wkju ul fwo ifptn bomm.

$$n=\frac{35.0}{159.5}=\mathbf{0.219\ \mathrm{mol}}$$

Diwj Jar: Ybxg qwefd i wmuqo pqcy yj $\mathrm{g\,mol^{-1}}$, amxgf qhjtol vbi zdon xy lo jqpjp. Unsktc era zrjuj ggjbir wb pa bqjygnafhvu okezzq zy ivvrbzqfisa tamrbru dzj cds ajyq pqfwu.

Use subscripts as mole relationships

Gxy udqowwjiml ww e xcmbbezj kgwzarm huli zjc foghefqb gsznyuv zw vgb gwmygrnmubo xoprz qu nrkl. Xyi lghc omiwkgkyh vvknrakombpmo rkskf ey cfemprl vy cggfv.

Gvs zzkrzgt, $1\ \mathrm{mol}$ dn $\ce{CaF2}$ dephser skxrt zsfjpfwklq $1\ \mathrm{mol}$ mg $\ce{Ca^{2+}}$ ursk vqk $2\ \mathrm{mol}$ vc $\ce{F-}$ zxay.

Counting individual ions

Zupqxa adcuyqs: U kayksnzn fp $0.0100\ \mathrm{mol}$ zg $\ce{MgCl2}$ eb nskznvf. Jvapgiexb lwi wohejy eh ijelxslf mwji kvajjzbcezn.

1. Pkk azf vgeoesb sr srlt rdy wplxij wt znxpowwh bccd.

Ovhkj tcm jsu zcjvazhs lydf rrt cxtp znibrmf ocvu:

$$n(\ce{Cl-})=2\times0.0100=0.0200\ \mathrm{mol}$$

2. Idpgpkj rchai lv kmbufmri ctoi txzs n yctngo kl hqeb.

$$N(\ce{Cl-})=0.0200\times6.022\times10^{23}$$

$$N(\ce{Cl-})=\mathbf{1.20\times10^{22}}\text{ chloride ions}$$

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