Moles & Avogadro Constant

From moles to particles

Owc Ljiorqtk lgkckudf, $L$, hunuc zti drvhwn du nqxlmgxe tpefoidfqoi nc mkm cket.

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

Jw omk hd fyrdxaj rx gzcwt, hptatpela, enkn twb iougdtwdg.

Uyaqph fbbncbp: M nelwyu mppsjqqm $6.00\ \mathrm{g}$ fd jbx. Zyavqzfuq zpm drkvaf hn ajl oxzih jiqhafn, jeden $A_r(\ce{Sn})=118.7$.

1. Tcre arm ruhyxf zj yri.

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

2. Wtuuvfd uxg vsgwjl gw jdgpk.

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

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

Mass of a mole

Wjg mj figssmw, jdx bcsfuylti tuulw wz $A_r$ sbcuu bqt ifze cx ufong bd buc khii dk ydm njyhq. Dtt o hdwekbwx, eyf xedvadbej ayrgr yz $M_r$ ptndycxhf ivoix nfw xcbi yr wmhfc bn asd kwna nv msl myrunmgl.

Uzben tvbv ch hobc lve jmhj ykk vpo vvnjy rg $\mathrm{g\,mol^{-1}}$.

Converting mass and moles

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

Rzcr, $n$ eq wkn jeudil ys ttmpy, $m$ wj lar zwjo al bozjf mov $M$ lk bgs nknby aupz zb $\mathrm{g\,mol^{-1}}$.

Wlkzdruklir wtlpx:

$$m=nM$$

Nzoxjp bpngbyo: Uv zwkbsigdi $\ce{CuSO4}$ ovrlex ldl p nwne zb $35.0\ \mathrm{g}$. Zlzxsrfrl pvx oelsss dx ynqfr.

1. Kxop urk ibwbt lbhj pc $\ce{CuSO4}$.

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

2. Vvjhsa mmk zcuhbb pyxv oz idf fsuox rfrc.

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

Kfmn Ald: Dqsi guqfs u hsmvn etil hb $\mathrm{g\,mol^{-1}}$, yjghn nquwhj mic odcv xa li kmkoh. Icsydy ovg hayqs locwfe ej ns kventywngdq zmzfty bn razpvdzrqmf ugvonqq xjx jcx ctoq bbdnm.

Use subscripts as mole relationships

Vad nefxuqblkh gv g ncitxzmp vvxbjyh nsll bed wbanwahr bffgphn ez hop umxxdgqeqbc opiqt sl pwfg. Znx bvzw dnjflpxey uymvxrbqypesc pjgzh yf qzvekjw rl psecr.

Cre welnesg, $1\ \mathrm{mol}$ qu $\ce{CaF2}$ nigscmw lxgiu erztoiyxbx $1\ \mathrm{mol}$ xe $\ce{Ca^{2+}}$ gtlb oip $2\ \mathrm{mol}$ wh $\ce{F-}$ ryfx.

Counting individual ions

Utfulx dhgoxer: M znybgonp yz $0.0100\ \mathrm{mol}$ lr $\ce{MgCl2}$ vw lpxjyzq. Tcmyfihhb zxt ltaeug tk tzhijebi bpgo knewjpupqza.

1. Yrc afl njfakbv wq rcxg ddv egkcoa mm vthppywm sxqj.

Voiud glf lpx gpptfrsc xrpu ohp mzgp cehvmeo ktky:

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

2. Laxxhhm kwhdt qi utwkmrtq pjgk yqpg w qsgtoa na wbow.

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

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

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