How many moles are in 68 grams of copper (II) hydroxide, #Cu(OH)2#?

1 Answer
Nov 28, 2015

Answer:

There are #0.70# moles of #Cu(OH)_"2"#.

Explanation:

We can use the following formula to determine the number of moles:

#m=nM#

where:
m = mass (grams)
n = number of moles
M = molar mass

To find the number of moles, we first have to find the molar mass of #Cu(OH)_"2"#. We can do this by adding the molar masses of copper, oxygen, and hydrogen together, accounting for the number of atoms for each element.

#M_color(brown)"copper"=color(brown)((63.55g)/(mol))#

#M_color(blue)"hydrogen"=(1.01g)/(mol)*2=color(blue)((2.02g)/(mol))#

#M_color(green)"oxygen"=(16.00g)/(mol)*2=color(green)((32.00g)/(mol))#

#M_color(purple)"copper (II) hydroxide"=color(brown)((63.55g)/(mol))+color(blue)((2.02g)/(mol))+color(green)((32.00g)/(mol))=color(purple)((97.57g)/(mol))#

Now we can substitute our known values into the formula to solve for number of moles:

#m=nM#

#n=m/M#

#n=68g-:color(purple)((97.57g)/(mol))#

#n=68g*(mol)/(97.57g)#

#n=68color(red)cancelcolor(black)(g)*(mol)/(97.57color(red)cancelcolor(black)(g))#

#n=(68mol)/97.57#

#n=0.6969355335 mol#

#n=0.70mol#

Note:
The final answer should always have the correct number of significant figures.

#:.#, there are #0.70# moles of #Cu(OH)_"2"#.