how many atoms of C are there in 25 grams of C5H12 ? (pentane)

Question

anonymous · Answer

LOOK AT the molecular formula of pentane .82 grams is molecular mass of pentane which is also molar mass of pentane                                                                                                        now  1 mole of  pentane  contains 5*AVAGADROS NUMBER carbons  atoms .now calculate the number of moles in 25 grams  i hope u illl understand

xishem · Answer

In a more mathematical sense:$$25g(C_5H_{12})*\frac{1mol(C_5H_{12})}{72.15g(C_5H_{12})}=0.346500mol(C_5H_{12})$$$$0.346500mol(C_5H_{12})*\frac{6.022*10^{23}mlcl(C_5H_{12})}{1mol(C_5H_{12})}=2.086625*10^{23}mlcl(C_5H_{12}))$$
Since each molecule of pentane contains 5 atoms of carbon:$$2.086625*10^{23}mlcl(pentane)*\frac{5atoms(C)}{1mlcl(pentane)}=1.0*10^{24}atoms(C)$$We're only justified in keeping 2sigfigs in the final answer.