Question

a cube of volume 6ml is immersed fully in water. calculate the upward force experienced by the water. density of water is 1000kg/m cube, g =9.8m/s Sq.

Answer 1

We're asked to find the volume occupied by
1

molecule
of
H
2
O
.

We can find this through a few steps:

Convert molecules to moles via Avogadro's number

Convert moles to grams via molar mass

Convert grams to cubic centimeters (milliliters) via density

Step 1:

We'll first convert the one molecule of water to moles, using Avogadro's number:

1
molecule H
2
O
(
1
l
mol H
2
O
6.022
×
10
23
molecules H
2
O
)

=
1.66
×
10
−
24

mol H
2
O

Step 2:

Now, using the molar mass of water (
18.02

g/mol
), we'll calculate the number of grams:

1.66
×
10
−
24
mol H
2
O
(
18.02
l
g H
2
O
1
mol H
2
O
)

=
2.99
×
10
−
23

g H
2
O

Step 3:

Finally, knowing that
1

g
water occupies a volume of
1

cm
3
(or
1

mL
, which is more conventional for liquids), we can calculate the volume occupied by one molecules of water:

2.99
×
10
−
23
g H
2
O
(
1
l
mL
1
g H
2
O
)

=
2.99
×
10
−
23

mL H2O
Hope it helps you.