How many atoms are in 153 g of calcium?

1 Answer
Nathan L.
Jun 7, 2017

#2.30 xx 10^24# #"atoms Ca"#

Explanation:

We're asked to calculate the number of atoms of #"Ca"# in #153# #"g Ca"#.

What we must first do is convert the given mass of calcium to moles of calcium, using its molar mass (referring to a periodic table, this is #40.08"g"/"mol"#):

#153# #cancel("g Ca")((1"mol Ca")/(40.08cancel("g Ca"))) = color(blue)(3.82# #color(blue)("mol Ca"#

Using Avogadro's number, #6.022 xx 10^23"particles"/"mol"#, we can calculate the number of atoms present:

#color(blue)(3.82# #cancel(color(blue)("mol Ca"))((6.022xx10^23"atoms Ca")/(1cancel("mol Ca")))#

#= color(red)(2.30 xx 10^24# #color(red)("atoms Ca"#

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