Question #fd627

1 Answer
Jul 30, 2017

Answer:

#8xx10^23# #"protons "# (one significant figure)

Explanation:

We're asked to find the number of nucleic protons in #2# #"g CH"_4#.

To do this, we can first use the molar mass of methane to convert from grams to moles:

#2cancel("g CH"_4)((1color(white)(l)"mol CH"_4)/(16.04cancel("g CH"_4))) = color(red)(0.1247# #color(red)("mol CH"_4#

Now, we can use Avogadro's number to convert from moles to molecules of methane:

#color(red)(0.1247)cancel(color(red)("mol CH"_4))((6.022xx10^23color(white)(l)"molecules CH"_4)/(1cancel("mol CH"_4)))#

#= color(green)(7.508xx10^22# #color(green)("molecules CH"_4#

Finally, we use the atomic number of each element to find the total number of protons; we know:

#"carbon" = 6#

#"hydrogen" = 1 xx overbrace(4)^"four atoms per molecule" = 4#

For a total of

#6+4=ul(10# #"protons"#

per molecule.

Therefore,

#color(green)(7.508xx10^22)cancel(color(green)("molecules CH"_4))((10color(white)(l)"protons")/(1cancel("molecule CH"_4))) = color(blue)(ul(8xx10^23color(white)(l)"protons"#

rounded to #1# significant figure.