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:
Burning of paper is not a physical change.It is chemical change as ash is formed in the process which is new compound and oxides of carbon are also released during the process!
Answer:
d. Two moles of carbon dioxide were produced from this reaction
Explanation:
The given chemical reaction can be written as follows;
2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O
From the above chemical reaction, we have;
Two moles of C₂H₂ reacts with five moles of O₂ to produce four moles of CO₂ and two moles of H₂O
We have;
One mole of C₂H₂ will react with two and half moles of O₂ to produce <em>two moles of CO₂</em> and one mole of H₂O
Therefore, in the above reaction, when one mole of C₂H₂ is used, two moles of CO₂ will be produced.
