Question

A solution is prepared by dissolving 4.40 g of KSCN in enough water to make 200 mL of solution. What is the concentration of the solution?

Answer 1

The concentration of solution is $\boxed{{\text{0}}{\text{.22635 mol/L}}}$ .

Further explanation:

Mole is the S.I. unit and number of moles is calculated as the ratio of mass of the compound to that of molar mass of the compound. Molar mass is the mass of different atoms present in a molecule.

The expression of number of moles, mass and molar mass of compound is as follows:

${\text{Number of moles}}=\frac{{{\text{mass of the compound}}}}{{{\text{molar mass of the compound}}}}$               …... (1)

Molarity:

The molarity of the solution can be defined as the concentration of the solution and is equal to the number of moles of the solute dissolved in 1 liter of the solution.

The expression to relate molarity (M), volume (V), and number of moles (n) is as follows:

${\text{M}}=\frac{{{\text{n}}\left({{\text{mol}}}\right)}}{{{\text{V}}\left({\text{L}}\right)}}$       …… (2)

Here, V is a volume of solution in liters and n is a number of moles of solute.

Given mass of KSCN is 4.40 g.

Molar mass of KSCN is 97.1807 g/mol.

Substitute these values in equation (1) to calculate the number of moles of KSCN.

$\begin{aligned}{\text{number of moles}}&=\frac{{{\text{4}}{\text{.40g}}}}{{{\text{97}}{\text{.1807g/mol}}}}\\&={\text{0}}{\text{.04527 mol}}\\\end{aligned}$

The number of moles of KSCN is 0.04527 mol.

The conversion factor to convert volume in liter (L) to (mL) is as follows:

${\text{1L}}=1000\;{\text{mL}}$

Given volume of solution is 200 mL.

Therefore, 200 mL of volume is converted into (L) as follows

$\begin{aligned}{\text{Volume}}&=\,{\text{200 mL}}\left({\frac{{{\text{1}}\;{\text{L}}}}{{1000\;{\text{mL}}}}}\right)\\&={\text{0}}{\text{.2 L}}\\\end{aligned}$

Number of moles of KSCN is 0.04527 mol.

Volume of solution is .02 L.

Substitute these values in equation (2) to calculate the concentration of solution.

$\begin{aligned}{\text{M}}&=\frac{{{\text{0}}{\text{.04527 mol}}}}{{{\text{0}}{\text{.2 L}}}}\\&={\text{0}}{\text{.22635 mol/L}}\\\end{aligned}$

Hence, the concentration of solution is 0.22635mol/L.

Learn more:

1.Write equation to show how cation act as an acid: brainly.com/question/2396649.

2. Determine the characteristics of mixtures: brainly.com/question/1917079.

Answer details:

Grade: Senior solution

Subject: Chemistry

Chapter: Mole concept

Keywords: Molar mass, KSCN, number of moles, concentration, volume, solute, 1 liter, molarity, 0.22635 mol/L.

Answer 2

First find the number of moles of KSCN is in 4.40g of KSCN 1. Number of moles = mass given (4.40g) / molecular weight(MW) (KSCN) - to calculate MW, look for each element in the periodic table and add their atomic weight 2. Convert 200mL to liters 3. Concentration = number of moles/ volume in liters from (#2)