Question #a1c07

1 Answer
Jan 27, 2018

#=8.97xx10^22 C_3H_8 " molecules"#

Explanation:

  1. Write the balanced equation

    #C_3H_8(g)+5O_2(g)->3CO_2(g)+4H_2O(g)#

  2. Assuming that the #CO_2# gas produced from the reaction behaved ideally; thus, the relationship that #"1mol of any ideal gas occupies a volume of 22.4L"# is the equivalence statement needed to find the unknown variable and can be interpreted as:

    #"1mol of any ideal gas"##-=22.4L# #"of any ideal gas"#

  3. Given the desired volume of #CO_2#; that is, 10.0L and the relationship described above, it can be deduced that the number of moles #(eta)#:

    #eta=10.0cancel(L*CO_2)xx(1molCO_2)/(22.4cancel(L*CO_2))=0.446molCO_2#

  4. Now, find the number of moles of #C_3H_8#. To convert #etaCO_2# to #etaC_3H_8#, refer to the balanced equation for the mole ratio; i.e.,

    #=0.446cancel(molCO_2)xx(1molC_3H_8)/(3cancel(molCO_2))#
    #=0.149molC_3H_8#

  5. Knowing the number of moles of #C_3H_8#, the number of molecules can be obtained through the relationship:

    #"1mol of " C_3H_8# #-=6.02xx10^23C_3H_8 " molecules"#

  6. Now, using the preceding equivalence statement where a suitable conversion factor is obtainable, the number of molecules of #C_3H_8# is;

    #=0.149cancel(molC_3H_8)xx(6.02xx10^23C_3H_8 " molecules")/(1cancel(molC_3H_8))#
    #=0.897xx10^23C_3H_8" molecules"#
    #=8.97xx10^22C_3H_8 " molecules"#