Preparo de NaOH 1,0 Molar {Química #031}

Summary

In this video, Paul Sams demonstrates how to prepare a sodium hydroxide (NaOH) solution with a concentration of 1 molar. He walks through the process of measuring the required mass of NaOH, dissolving it in distilled water, and transferring the solution into a 100 ml volumetric flask. Emphasizing safety due to the corrosive nature of NaOH, Paul highlights the importance of careful measurement and precise volume completion to ensure the correct concentration. He concludes by explaining the need for solution standardization to achieve the exact concentration and shares helpful tips for accuracy.

Takeaways

• 😀 The video teaches how to prepare a sodium hydroxide (NaOH) solution of 1 Molar concentration.
• 😀 The formula used to prepare the solution is mass of solute over molar mass, multiplied by volume.
• 😀 Sodium hydroxide is corrosive, so safety measures like wearing gloves and goggles are essential.
• 😀 The molar mass of sodium hydroxide (NaOH) is 40 g/mol, and for 100 ml of a 1 M solution, you need 4 grams of NaOH.
• 😀 The video demonstrates using a balance to measure the exact mass of NaOH and the necessary equipment.
• 😀 The tare function on the balance is used to subtract the weight of the container to get the weight of NaOH alone.
• 😀 Once the NaOH is weighed, it's dissolved in distilled water in a 100 ml volumetric flask.
• 😀 The video emphasizes the importance of quantitative transfer to ensure all NaOH is moved into the flask.
• 😀 After transferring the NaOH, the solution volume is adjusted to exactly 100 ml using a graduated pipette or drop-by-drop method.
• 😀 The final solution must be carefully mixed by swirling the flask three times to ensure uniformity.
• 😀 The solution's concentration may not be exactly 1 M after preparation, so it must be standardized to determine the precise concentration.

Q & A

What is the purpose of this video?

The purpose of the video is to teach viewers how to prepare a sodium hydroxide solution with a specific concentration.

What is the formula used to prepare the sodium hydroxide solution?

The formula used is: Mass of solute = Concentration × Volume × Molar Mass of Sodium Hydroxide.

How much sodium hydroxide is needed to prepare a 100 mL 1 M solution?

To prepare a 100 mL 1 M solution of sodium hydroxide, you need 4 grams of sodium hydroxide.

What is the molar mass of sodium hydroxide?

The molar mass of sodium hydroxide is 40 g/mol.

What is the purpose of taring the balance before weighing the sodium hydroxide?

Taring the balance ensures that the weight of the container is excluded, so only the mass of the sodium hydroxide is measured.

Why is it important to handle sodium hydroxide with care?

Sodium hydroxide is highly corrosive, and improper handling can cause burns or injury. Always wear gloves and goggles for safety.

What should be done if any sodium hydroxide remains on the container after transferring it to the flask?

If any sodium hydroxide remains on the container, you should rinse it with distilled water to ensure that all of it is transferred to the volumetric flask.

What is the significance of filling the volumetric flask to the exact 100 mL mark?

Filling the flask to the exact 100 mL mark ensures that the concentration of the solution is correct. Overfilling or underfilling will alter the concentration.

Why is the solution considered 'theoretically' 1 M initially?

The solution is considered 'theoretically' 1 M because the actual concentration may vary slightly due to the precision of measurements and the standardization process.

What does 'standardizing' the solution mean?

Standardizing the solution involves using a primary standard to determine the exact concentration of the solution, ensuring it matches the intended concentration.