Answer:
2.0 moles
Explanation:
The relationship between the number of moles of a given substance present in a sample and the mass of the sample is given by the molar mass of the substance.
For any chemical species, you have
molar mass
=
the mass of exactly 1 mole
water has a molar mass of
18.015 g mol
−
1
which means that
1
mole of water has a mass of
18.015 g
.
18.015 g mol
−
1
=
18.015 g
1 mole H
2
O
So for every
18.015 g
of water present in your sample, you have
1
mole of water.
This means that your
36-g
sample will contain
36
g
⋅
given by the molar mass of H
2
O
1 mole H
2
O
18.015
g
=
2.0 moles H
2
O
~~~
The answer must be rounded to two sig figs, the number of sig figs you have for the mass of water.
Explanation:
