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QJEEM24Ch15c5: JEE Main 2024 Chemistry - Class 11 JEEM24Ch15c5 Solution: Volume of (formula weight ) which can be prepared from of is…

Volume of 3M NaOH3 \mathrm{M} \mathrm{~NaOH} (formula weight 40 g mol−140 \mathrm{~g} \mathrm{~mol}^{-1} ) which can be prepared from 84 g84 \mathrm{~g} of NaOH\mathrm{NaOH} is __________ ×10−1dm3\times 10^{-1} \mathrm{dm}^3 .

Step-by-Step Verified Solution

First, let's calculate the number of moles of NaOH that can be prepared from 84 g84\ \text{g} of NaOH. The molar mass of NaOH is given as 40 g/mol40\ \text{g/mol} .

The number of moles (n) is calculated using the formula:

n=massmolar massn = \frac{mass}{molar\ mass}

So for our case:

n=84 g40 g/mol=2.1 moln = \frac{84\ \text{g}}{40\ \text{g/mol}} = 2.1\ \text{mol}

Now that we know the number of moles, we can find out the volume of a 3 M3\ \text{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=nVC = \frac{n}{V}

Where: C = concentration in molarity (M) n = number of moles V = volume in liters (L) - Note that 1 dm3=1 L1\ \text{dm}^3 = 1\ \text{L} .

Since we want to find the volume (V), we can rearrange the formula to solve for V:

V=nCV = \frac{n}{C}

Using the moles of NaOH and the concentration for the preparation:

V=2.1 mol3 MV = \frac{2.1\ \text{mol}}{3\ \text{M}}

Calculate the volume:

V=2.13=0.7 LV = \frac{2.1}{3} = 0.7\ \text{L}

To convert this volume to dm3\text{dm}^3 (which is equivalent to liters), we use the conversion factor 1 L=1 dm31\ \text{L} = 1\ \text{dm}^3 . Therefore:

V=0.7 dm3V = 0.7\ \text{dm}^3

To express this volume as ×10−1 dm3\times 10^{-1}\ \text{dm}^3 , we can write:

V=7×10−1 dm3V = 7 \times 10^{-1}\ \text{dm}^3

Therefore, the volume of 3 M3\ \text{M} NaOH solution which can be prepared from 84 g84\ \text{g} of NaOH is 7×10−1 dm37 \times 10^{-1}\ \text{dm}^3 .

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