Question

What is the concentration of a NaCl solution if 86.00 g of solute was dissolved in enough water to form 1000. ml of solution?

Answer 1

Answer:

Explanation:

The molality of a solution essentially relates the number of moles of solute and the mass of the solvent.

More specifically, molality is defined as the number of moles of solute, which in your case is sodium chloride,

NaCl

, present in one kilogram of solvent, which is water.

To find the number of moles of sodium chloride present in your sample, sue the compound's molar mass

25

g

⋅

1 mole NaCl

58.44

g

=

0.428 moles NaCl

Now, you know that you're dissolving this many moles of sodium chloride in

20 kg

of water. You can thus use the composition of this solution to find the number of moles of solute present in

1 kg

of water

1

kg water

⋅

0.428 moles NaCl

20

kg water

=

0.0214 moles NaCl

Rounded to one significant figure, the number of sig figs you have for the mass of water, the molality of the solution will be

¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

∣

∣

a

a

molality

=

0.02 mol kg

−

1

a

a

∣

∣

−−−−−−−−−−−−−−−−−−−−−−−−−−−

Answer 2

The concentration of a NaCl solution is 1.47 M.

Given:

86.00 g of solute was dissolved in enough water to form 1000. ml of solution.

To Find:

The concentration of a NaCl solution.

Solution:

To find the concentration of a NaCl solution, we will follow the following steps:

As we know,

The molecular mass of NaCl = 58.4g/mol

Molarity is given by the formula:

$Molarity = \frac{given \: mass}{molecular \: mass \times volume \: in \: ml} \times 1000$

Now,

On putting values in the above formula we get,

$Molarity = \frac{86}{58.4 \times 1000} \times 1000 = 1.47 \: M$

Henceforth, the concentration of a NaCl solution is 1.47 M.

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