Exam
Chemistry
Volume of 3M NaOH (formula weight 40 g mol−1 ) which can be prepared from 84 g of NaOH is __________ ×10−1dm3.
Correct Answer:
7
Explanation
First, let's calculate the number of moles of NaOH that can be prepared from
84 g
of NaOH. The molar mass of NaOH is given as 40 g/mol
.
The number of moles (n) is calculated using the formula:
n=molar massmass
So for our case:
n=40 g/mol84 g=2.1 mol
Now that we know the number of moles, we can find out the volume of a
3 M
NaOH solution that can be prepared from it. The concentration (C) of a solution is related to the number of moles (n) and volume (V) by the following formula:
C=Vn
Where: C = concentration in molarity (M) n = number of moles V = volume in liters (L) - Note that
1 dm3=1 L
.
Since we want to find the volume (V), we can rearrange the formula to solve for V:
V=Cn
Using the moles of NaOH and the concentration for the preparation:
V=3 M2.1 mol
Calculate the volume:
V=32.1=0.7 L
To convert this volume to
dm3
(which is equivalent to liters), we use the conversion factor 1 L=1 dm3
. Therefore:
V=0.7 dm3
To express this volume as
×10−1 dm3
, we can write:
V=7×10−1 dm3
Therefore, the volume of
3 M
NaOH solution which can be prepared from 84 g
of NaOH is 7×10−1 dm3
. Select an option to instantly check whether it is correct or wrong.
