Question #90540

1 Answer
Aug 4, 2017

Answer:

#60# #"mol H"_2"O"# (#1# significant figure)

Explanation:

We're asked to find the number of moles of water in #1# #L"# water, given its density.

The given density of #1# #"g/cm"^3# is equivalent to #1# #"g/mL"#, which is also equal to

#((1color(white)(l)"g")/(1cancel("mL")))((10^3cancel("mL"))/(1color(white)(l)"L")) = color(red)(ul(10^3color(white)(l)"g/L"#

Now, we can use dimensional analysis to convert from #1# #"L H"_2"O"# to grams:

#1cancel("L H"_2"O")((color(red)(10^3color(white)(l)"g H"_2"O"))/(1cancel("L H"_2"O"))) = color(green)(ul(10^3color(white)(l)"g H"_2"O"#

Lastly, we'll use the molar mass of water (#18.015# #"g/mol"#) to calculate the number of moles:

#color(green)(10^3)cancel(color(green)("g H"_2"O"))((1color(white)(l)"mol H"_2"O")/(18.015cancel("g H"_2"O"))) = color(blue)(ulbar(|stackrel(" ")(" "60color(white)(l)"mol H"_2"O"" ")|)#

rounded to #1# significant figure.