Preparing a 10% m/m Solution

We can have different types of mixtures Depending on the nature of the components that form a mixture.

1. A mixture whose composition is uniform is called a homogeneous mixture or solution. 
2. Mixtures that contain physically distinct parts and have non-uniform compositions are called heterogeneous mixtures. 

Homogeneous Mixtures

A solution is a homogeneous mixture of two or more substances. A solution has a solvent and a solute as its components. The component of the solution that dissolves the other component in it (usually the component present in larger amounts) is called the solvent. The component of the solution that is dissolved in the solvent (usually present in lesser quantity) is called the solute. 

Eg: A solution of salt in water 

Heterogeneous Mixtures

Heterogeneous mixtures can be either suspensions or colloids. 

A solution is a homogeneous mixture of two or more substances. It has two components. The component that dissolves the other components in it is called the solvent. The component that dissolves in the solvent is called the solute. The relative proportion of the solute and solvent can be varied. 

Concentration of a Solution

The concentration of a solution is the amount of solute present in a solution. 

There are various ways of expressing the concentration of a solution, but here we will learn only three methods. 

(i) Mass by mass percentage of a solution = (Mass of solute / Mass of solution) ×100 

For example, If a solution contains 40 g of common salt in 320 g of water, then 

Mass of solute (salt) = 40 g 

Mass of solvent (water) = 320 g 

We know, Mass of solution = Mass of solute + Mass of solvent = 40 g + 320 g = 360 g 

Mass percentage of solution = (Mass of solute /Massof solution) ×100

                                              = (40/360) ×100

                                              = 11.1%

(ii) Mass by volume percentage of a solution =(Mass of solute /Volume of solution) ×100

(iii) Volume by volume percentage of a solution =(Volume of solute /Volume of solution) ×100

Preparing a 10% m/m solution of common salt (sodium chloride) in water.

The mass percentage of solute in a solution is the total mass of solute in a given mass of solution and is represented in percentage by multiplying by 100. 

A 10% solution by mass means 10 g of solute dissolved in 90 g of solvent to result into 100 g of solution. Let us study this through a simulation. 

This experiment aims to prepare a solution of common salt of 10% composition by mass (% m/m)

The materials and chemicals required for this experiment are: 

Materials and Apparatus Required

Apparatus:

• Digital balance 
• Watch glass
• Measuring cylinder – 100 mL
• Spatula
• Beaker – 250 mL
• Glass rod

Chemicals:

• Sodium chloride powder
• Distilled water 

Experiment Procedure

The procedure followed for this experiment is as follows: 

1. To prepare a solution of common salt of 10% composition by mass, 10 g of the salt must be dissolved in 90 mL of water. 
2. Take 90 mL (90 g) of distilled water in a 250 mL beaker with the help of a measuring cylinder. 
3. Take an empty watch glass on a digital balance and tare the balance. 
4. Weigh 10 g of sodium chloride (common salt) on the watch glass. 
5. Transfer 10 g of the salt from the watch glass to the beaker containing 90 mL of distilled water. 
6. Stir the solution until all the salt dissolves in it.

Conclusion

Thus, it can be concluded that, 

• A 10% NaCl solution by mass has 10 g of sodium chloride dissolved in 100 g of solution.
• A 10% NaCl solution, if prepared in 100 g of solution, contains 10 g NaCl in 90 mL H₂O.

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