I believe 212.5m, but I may be wrong, I’m a little rusty with moles
The idea here is that you need to figure out how many moles of magnesium chloride,
MgCl
2
, you need to have in the target solution, then use this value to determine what volume of the stock solution would contain this many moles.
As you know, molarity is defined as the number of moles of solute, which in your case is magnesium chloride, divided by liters of solution.
c
=
n
V
So, how many moles of magnesium chloride must be present in the target solution?
c
=
n
V
⇒
n
=
c
⋅
V
n
=
0.158 M
⋅
250.0
⋅
10
−
3
L
=
0.0395 moles MgCl
2
Now determine what volume of the target solution would contain this many moles of magnesium chloride
c
=
n
V
⇒
V
=
n
c
V
=
0.0395
moles
3.15
moles
L
=
0.01254 L
Rounded to three sig figs and expressed in mililiters, the volume will be
V
=
12.5 mL
So, to prepare your target solution, use a
12.5-mL
sample of the stock solution and add enough water to make the volume of the total solution equal to
250.0 mL
.
This is equivalent to diluting the
12.5-mL
sample of the stock solution by a dilution factor of
20
.
Answer:
The porpoise would hear its echo first because sound travels faster in water than in air. The bat would hear its echo first because the amplitude of sound waves ...
Explanation:
Answer:
Discovery of neutron
Explanation:
Until 1932, the atom was believed to be composed of a positively charged nucleus surrounded by negatively charged electrons, after successful discovery of electron by J.J. Thompson and proton by Ernest Rutherford.
In 1932, James Chadwick bombarded beryllium atoms with alpha particles.
As Chadwick had previously seen in experiment conducted by Frédéric and Irène Joliot-Curie, they had bombarded a sample of beryllium with alpha radiation.
Chadwick repeated the experiment and observed an unknown radiation, this showed no deflection what-so-ever.
He repeated this experiment by bombarding other materials, like helium, nitrogen and lithium,
Finally, Chadwick found that this radiation was composed of particles with a neutral electrical charge and had approximate mass of a proton.
This particle was then known as the neutron.
