Question #745a3

1 Answer
Apr 7, 2016

Answer:

#"2.504 moles TiO"_2#

Explanation:

The problem provides you with grams of titanium(IV) oxide, #"TiO"_2#, and asks you to determine how many moles would be present in that many grams.

This means that you're looking for a conversion factor that can take you from grams to moles and vice versa.

For any compound, this conversion factor is called the molar mass. The molar mass tells you the mass of exactly one mole of a given compound.

In you case, you can use the molar mass of titanium(IV) oxide, which is equal to #"79.866 g mol"^(-1)#, to find out how many moles you get in tha t#"200.0-g"# sample.

So, a molar mass of #"79.866 g mol"^(-1)# tells you that one mole of titanium(IV) oxide has a mass of #"79.866 g"#. This means that you have

#200.0 color(red)(cancel(color(black)("g"))) * overbrace("1 mole TiO"_2/(79.866color(red)(cancel(color(black)("g")))))^(color(purple)("molar mass of TiO"_2)) = color(green)(|bar(ul(color(white)(a/a)"2.504 moles TiO"_2color(white)(a/a)|)))#

The answer is rounded to four sig figs, the number of sig figs you have for the mass of titanium(IV) oxide.