Percent Concentrations - Online Tutor, Practice Problems & Exam Prep

Mass percent concentration indicates the grams of solute in a solution, while mass/volume (m/v) percent concentration is calculated as the grams of solute divided by the milliliters of solution, multiplied by 100%. Similarly, volume/volume (v/v) percent concentration represents the milliliters of solute in a given volume of solution, calculated as milliliters of solute divided by milliliters of solution, multiplied by 100%. Understanding these concepts is essential for accurately expressing solution concentrations in various chemical contexts.

Percent Concentrations Concept 1

Now recall that mass percent is the percentage of a given solute in grams within a solution, also in grams. And what we can understand is that additionally, we can use mass/volume and volume percent formulas to express solution concentrations. Now here, we're going to deal with what we call mass volume, abbreviated as m/v percent concentration. We're gonna say this represents a percentage of a given solute in grams dissolved in a given volume in milliliters of solution. So that means that our m/v formula equals grams of our solute divided by milliliters of solution times 100%. This will allow us to calculate the mass volume percentage for any given solution.

Percent Concentrations Example 1

A solution was prepared by dissolving 13.5 grams of potassium nitrate in sufficient water to produce 85 ml of solution. What is the mass volume percentage of this solution? Alright. So we're going to say here mass volume percentage equals the grams of our solute divided by milliliters of our solution times 100%. Here our solute is potassium nitrate, so that's 13.5 grams of potassium nitrate divided by the ml of solution, which is 85, times 100%. When we do that we get 15.9% as our final answer. Here, the answer has 3 significant figures because both 13.5 and 85.0 also have 3 significant figures.

Percent Concentrations Concept 2

With volume volume percentages, we say it represents a percentage of a given solute in milliliters dissolved in a given volume of milliliters for a solution. That means that our volume volume percentage, so volume volume is abbreviated as v/v percentage equals the ml's of solute divided by the ml's of solution times 100%.

v / v % = ml solute ml solution × 100 %

How many mL of ethanol are contained in a 750.0 mL bottle of wine that contains 11.0% (v/v) of ethanol?

• A. 1.5 mL
• B. 68.2 mL
• C. 82.5 mL
• D. 11.0 mL

Calculate the grams of solute needed to prepare the following:450 mL of a 2.0% m/v KOH solution.

• A. 1.1 g
• B. 9.0 g
• C. 4.5 g
• D. 2.3 g

What is the mass/volume percent concentration of the following solutions:0.075 mol sucrose (C₁₂H₂₂O₁₁) in 270 mL of solution.

• A. 5.0 m/v %
• B. 2.8 m/v %
• C. 6.7 m/v %
• D. 9.5 m/v %

The pain reliever ibuprofen is sold as an oral suspension for children 2-11 years of age. How many milligrams would you obtain in a 2.7 tsp dose if it contains 100 mg per 5 mL? (1 tsp = 5 mL)

• A. 1.0×10² mg
• B. 67 mg
• C. 2.7×10² mg
• D. 54 mg

Here’s what students ask on this topic:

What is mass percent concentration and how is it calculated?

Mass percent concentration is a way to express the concentration of a solute in a solution. It is calculated by taking the mass of the solute (in grams) and dividing it by the total mass of the solution (also in grams), then multiplying the result by 100% to get a percentage. The formula is:

$\frac{\mathrm{mass} \mathrm{of} \mathrm{solute}}{\mathrm{mass} \mathrm{of} \mathrm{solution}}\times 100\%$

This method is useful for understanding the proportion of solute in a given solution.

How do you calculate mass/volume percent concentration?

Mass/volume percent concentration (m/v) is calculated by taking the mass of the solute (in grams) and dividing it by the volume of the solution (in milliliters), then multiplying the result by 100% to get a percentage. The formula is:

$\frac{\mathrm{grams} \mathrm{of} \mathrm{solute}}{\mathrm{milliliters} \mathrm{of} \mathrm{solution}}\times 100\%$

This type of concentration is particularly useful in medical and laboratory settings where solutions are often prepared by dissolving a solid solute in a liquid solvent.

What is volume/volume percent concentration and how is it calculated?

Volume/volume percent concentration (v/v) is a way to express the concentration of a solute in a solution where both the solute and the solution are liquids. It is calculated by taking the volume of the solute (in milliliters) and dividing it by the total volume of the solution (also in milliliters), then multiplying the result by 100% to get a percentage. The formula is:

$\frac{\mathrm{milliliters} \mathrm{of} \mathrm{solute}}{\mathrm{milliliters} \mathrm{of} \mathrm{solution}}\times 100\%$

This method is commonly used in chemistry and biology labs to prepare solutions with precise concentrations.

Why is understanding percent concentrations important in chemistry?

Understanding percent concentrations is crucial in chemistry because it allows scientists and students to accurately describe the composition of solutions. This is important for various applications, including chemical reactions, where the concentration of reactants can affect the rate and outcome of the reaction. It is also essential in fields like pharmacology, where precise concentrations of drugs are necessary for efficacy and safety. Additionally, percent concentrations are used in everyday products, such as cleaning solutions and beverages, making it a practical skill for both academic and real-world applications.

Can you provide an example of calculating mass/volume percent concentration?

Sure! Let's say you have a solution containing 5 grams of salt dissolved in 100 milliliters of water. To calculate the mass/volume percent concentration (m/v), you would use the formula:

$\frac{\mathrm{grams} \mathrm{of} \mathrm{solute}}{\mathrm{milliliters} \mathrm{of} \mathrm{solution}}\times 100\%$

Substituting the values, we get:

$\frac{5}{100}\times 100\%$

This simplifies to 5%, meaning the mass/volume percent concentration of the solution is 5%.