What is the mass of Cl in 21 g of NaCl?

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Answer 1 · 2015-11-07T18:27:31

12.78g

21g of #NaCl# is equivalent to 0.36mol.

#Na# (atomic mass = 23 g/mol), #Cl# (atomic mass = 35.5g/mol)

Mole = #("Atomic Mass") ("Molar Mass")#

Total molar mass of #NaCl# = 23 + 35.5 = 58.5 g/mol

Mole = #21 cancel g NaCl# x #"1 mol"/ (58.5 cancel g) NaCl# = 0.36 mol NaCl

1 mol of NaCl consists of 1 mol of Na ion and 1 mol of Cl ion

or

#NaCl# #rarr# #Na^+# + #Cl^-#

Therefore, 0.36mol of NaCl is equal to 0.36mol of Cl.

Mass of Cl = (Mole #Cl#) (Atomic Mass #Cl#)

Mass of Cl = #0.36 "mol Cl"# x #"35 g"/ (1 cancel "mol") Cl#

Mass of Cl = 12.78g #Cl#