Percent Solutions

Summary

This video script explains the concept of percentage solutions, focusing on three types: mass/mass, volume/volume, and mass/volume solutions. It details how to calculate the components of each type using examples like a 15% sugar solution in water, a 15% alcohol solution, and a 15% glucose solution. Key differences between the types are highlighted, such as mass being used for mass/mass solutions, volume for volume/volume solutions, and a combination of both for mass/volume solutions. The script also covers practical applications, such as the use of mass/volume solutions in biology and medicine.

Takeaways

• 😀 Mass/mass (or weight/weight) solutions focus on measuring the solute and solvent by mass.
• 😀 Volume/volume solutions involve measuring both the solute and solvent by volume, typically involving two liquids.
• 😀 Mass/volume solutions combine both mass for the solute and volume for the solution itself.
• 😀 In mass/mass solutions, the percentage of solute is based on its mass relative to the total mass of the solution.
• 😀 A 15% sugar solution by mass means 15g of sugar and 85g of water for a total mass of 100g.
• 😀 For volume/volume solutions, the concentration is calculated by volume, such as 15mL of alcohol in 100mL of solution.
• 😀 In volume/volume solutions, the total volume is the sum of the solute and solvent, though they may not add up exactly due to the nature of mixing liquids.
• 😀 Mass/volume solutions express concentration as grams of solute per 100mL of solution.
• 😀 A 15% mass/volume glucose solution means there are 15g of glucose for every 100mL of the solution.
• 😀 Mass/volume solutions are commonly used in biological and medical contexts, like glucose solutions in IV drips.

Q & A

What are the three types of percent solutions mentioned in the script?

The three types of percent solutions are mass/mass (sometimes called weight/weight), volume/volume, and mass/volume (sometimes called weight/volume).

What is the key distinction between mass/mass and volume/volume solutions?

Mass/mass solutions are made with weight or mass of substances, while volume/volume solutions are made by combining liquids, where the percent is based on the volume of each liquid used.

How is a mass/mass solution prepared, as described in the script?

A mass/mass solution is prepared by taking a certain percentage of mass (e.g., 15%) of a substance (like sugar) and mixing it with enough water to achieve the total mass, such as 100 grams in the example given.

What is the significance of density in volume/volume solutions?

In volume/volume solutions, the density plays a role because the solution's density is likely greater than 1, which means the total volume of the solution might be less than the total volume of liquids used to make it.

How is a volume/volume solution created?

A volume/volume solution is made by taking a certain percentage of volume (e.g., 15%) of a solute (like alcohol) and adding enough solvent (e.g., water) to reach a total desired volume, such as 100 milliliters.

What is a mass/volume solution, and how is it prepared?

A mass/volume solution involves a certain number of grams of solute per 100 milliliters of solution. For example, in a 15% mass/volume glucose solution, 15 grams of glucose are dissolved in enough water to make 100 milliliters of the solution.

What does the 15% concentration in a mass/volume solution indicate?

The 15% concentration in a mass/volume solution indicates that there are 15 grams of solute (e.g., glucose) for every 100 milliliters of solution.

What would happen if you dissolved 67.5 grams of glucose in 450 milliliters of solution?

If you dissolved 67.5 grams of glucose in 450 milliliters of solution, the concentration would be 15% mass/volume, meaning the solution would have 15 grams of glucose per 100 milliliters of solution.

In the script, why is the volume of the solution not a concern for mass/mass solutions?

In mass/mass solutions, the focus is on the mass of the substances involved, and the total volume is not a concern because it’s the weight or mass of the solute and solvent that defines the solution.

Why is the mass/volume solution format commonly used in biology and medicine?

The mass/volume solution format is often used in biology and medicine because it is easy to measure and handle substances based on their mass relative to the volume of solution, such as preparing glucose solutions.