Chemistry - Preparation of a standard solution with sodium chloride

Summary

In this episode of Science A Plus, viewers are guided through the process of preparing a standard solution. A standard solution, with a precisely known concentration, is vital for accurate scientific experiments. The video walks through calculating the amount of sodium chloride needed, measuring and transferring the solute, mixing the solution, and ensuring accurate volume measurement. The importance of cleanliness, precision, and proper technique is emphasized. By the end, viewers will understand how to prepare a standard sodium chloride solution with a concentration of 1 mol/dm³ and 250 cm³ volume, essential for reliable laboratory results.

Takeaways

• 😀 A standard solution is a solution with a precisely known concentration of solute.
• 😀 Concentration is defined as the number of moles of solute divided by the volume of the solution.
• 😀 The unit of concentration is moles per cubic decimeter (mol/dm³).
• 😀 Accurate concentration measurements are essential for reliable laboratory experiments and industrial applications.
• 😀 To prepare a standard solution, you need to carefully measure both the solute and the volume of the solution.
• 😀 In the example, we are preparing a 1 mol/dm³ sodium chloride solution with a volume of 250 mL, requiring 14.625 grams of NaCl.
• 😀 Essential equipment for this procedure includes a volumetric flask, chemical balance, wash bottle, funnel, and sodium chloride.
• 😀 Precision in weighing the solute is crucial for an accurate standard solution.
• 😀 When filling the volumetric flask, always ensure the water meniscus is aligned with the calibration mark at eye level for accuracy.
• 😀 After mixing the solution, label it with the solution name, concentration, volume, and the date it was prepared to ensure proper identification.
• 😀 Cleanliness of instruments and careful washing during the transfer of chemicals are necessary to avoid impurities in the solution.

Q & A

What is a standard solution?

A standard solution is a solution in which the concentration of the solute is precisely known.

Why is concentration important in preparing a standard solution?

Concentration is important because it indicates the exact amount of solute in a given volume of solution, ensuring accurate experimental results and industrial applications.

What formula is used to calculate concentration?

The formula to calculate concentration is: Concentration = moles of solute / volume of solution (in cubic decimeters).

What are the units of concentration?

The unit of concentration is moles per cubic decimeter (mol/dm³).

What is the concentration and volume of the solution in this experiment?

In this experiment, the concentration of the solution is 1 mole per cubic decimeter (1 mol/dm³) and the volume is 250 cubic centimeters (0.250 dm³).

How much sodium chloride is required for this standard solution?

14.625 grams of sodium chloride are required to prepare the solution with the specified concentration and volume.

What equipment is needed to prepare the standard solution?

The necessary equipment includes a volumetric flask, wash bottle, watch glass, chemical balance, funnel, and sodium chloride.

Why is it important to observe the meniscus when filling the volumetric flask?

It is important to observe the meniscus because the lowest point of the meniscus must be aligned with the mark on the volumetric flask to ensure the volume is measured accurately.

What is the correct technique for mixing the solution in the volumetric flask?

The correct technique involves shaking the volumetric flask gently 2-3 times, avoiding direct contact with the bulb to prevent heat transfer, which could cause unwanted chemical reactions.

What information should be included on the label of the standard solution?

The label should include the name of the solution, its concentration, its volume, and the date it was prepared.