Answer:
Explanation:
Moles of sodium
=
130
⋅
g
22.99
⋅
g
⋅
m
o
l
−
1
=
5.65
⋅
m
o
l
.
Now you have the stoichiometric equation:
2
N
a
(
s
)
+
2
H
2
O
(
l
)
→
2
N
a
O
H
(
a
q
)
+
H
2
(
g
)
↑
⏐
If there are
5.65
⋅
m
o
l
of metal, clearly
5.65
⋅
m
o
l
2
dihydrogen gas are evolved......, i.e.
2.83
⋅
m
o
l
H
2
. Typically, in a question like this, you would also be asked to calculate the volume the gas occupies under standard conditions, and the
p
H
of the resultant solution (would it be high, low, neutral?).
Atomic radius increases down a group
No, the density of an object does not depend on its size.
A piece of glass with a volume of 10 cm³ may have a mass of 27 g. Its density is
<em>D</em> = <em>m</em>/<em>V</em> = 27 g/10 cm³ = 2.7 g/cm³
A piece of the same type of glass with a volume of 20 cm³ will have a mass
of 54 g. Its density is
<em>D</em> = <em>m</em>/<em>V</em> = 54 g/20 cm³ = 2.7 g/cm³
Thus, density does not change with the size of an object. Density is an <em>intensive property</em>.
