Question #fb855

1 Answer
Mar 15, 2016

Answer:

#0.20 M#

Explanation:

  1. The equation is
    #CaCO_3->CaO + CO_2#
  2. Find the formula masses of #CO_2# and #CaCO_3#
    #CaCO_3#=#100# grams per mole
    #Ca=1 #x# 40=40#
    #C=1 #x# 12=12#
    #O=3 #x# 16=48#
    #CO_2#=#44# grams per mole
    #C=1 #x# 12=12#
    #O=2 #x# 16=32#
  3. Find the mass of pure marble;
    #mass pure=(actual mass)(purity)#
    #mass pure=((10g)(0.50)#
    #mass pure=5 g#
  4. Convert mass #CaCO_3# to mole #CaCO_3#
    #5 cancel(g CaCO_3) #x# (1 mol CaCO_3)/(100 cancel(g CaCO_3)#
    #0.05 mol CaCO_3#
  5. Find the mol #CO_2#; referring to the equation it's observed that both compounds have same number of mole; thus
    #CO_2=0.05 mol#
  6. Convert #250 ml# to Li; #0.25 Li#
  7. Therefore, to find the Molarity(M) use the formula:
    #M=(n. mol)/(Li solution)#
    #M=(0.05 mol)/(0.25 Li)#
  8. #M=0.20 (mol)/(Li)# or #0.20M#