Question #2270c

1 Answer
Aug 10, 2017

Answer:

#8.43xx10^24# #"atoms C"#

Explanation:

We're asked to find the number of atoms of #"C"# necessary to produce #12.0# #"mol CO"#, given the reaction is

#2"B"_2"O"_3(s) + 7"C"(s) rarr "B"_4"C"(s) + 6"CO"(g)#

First, let's use the coefficients of the chemical equation to find the relative number of moles of #"C"# that react:

#12.0cancel("mol CO")((7color(white)(l)"mol C")/(6cancel("mol CO"))) = color(red)(ul(14.0color(white)(l)"mol C"#

Now, we'll use Avogadro's number (#6.022xx10^23# #"mol"^-1#) to convert from moles to atoms:

#color(red)(14.0)cancel(color(red)("mol C"))((6.022xx10^23color(white)(l)"atoms C")/(1cancel("mol C"))) = color(blue)(ulbar(|stackrel(" ")(" "8.43xx10^24color(white)(l)"atoms C"" ")|)#

rounded to #3# significant figures, the amount allowed in the problem.