The density of acetonitrile (CH 3 CN) is 0.786 g/mL and the density of methanol (CH 3 OH) is 0.791 g/mL. A solution is made by dissolving 22.5 mL of CH 3 OH in 98.7 mL of CH 3 CN. (b) What is the molality of the solution?

First, we need to calculate the mass of each component. The mass of a substance can be calculated by multiplying its volume by its density. So, calculate the mass of $$CH_{3}CN $$and $$CH_{3}OH $$using their respective volumes and densities.. Next, convert the mass of $$CH_{3}OH to $$moles. The molar mass of $$CH_{3}OH is $$approximately 32.04 g/mol. Divide the mass of $$CH_{3}OH by $$its molar mass to get the number of moles.. Molality is defined as the number of moles of solute (in this case, $$CH_{3}OH) $$per kilogram of solvent (in this case, $$CH_{3}CN). $$Convert the mass of $$CH_{3}CN $$from grams to kilograms by dividing by 1000.. Finally, calculate the molality by dividing the number of moles of $$CH_{3}OH by $$the mass of $$CH_{3}CN in $$kilograms. This will give you the molality of the solution in mol/kg.. Remember that molality is a measure of the concentration of a solution. It tells us how many moles of solute are present in a certain amount of solvent. In this case, it tells us how many moles of methanol are present in a certain amount of acetonitrile.

The density of acetonitrile (CH3CN) is 0.786 g/mL and the density of methanol (CH3OH) is 0.791 g/mL. A solution is made by dissolving 22.5 mL of CH3OH in 98.7 mL of CH3CN. (b) What is the molality of the solution?

First, we need to calculate the mass of each component. The mass of a substance can be calculated by multiplying its volume by its density. So, calculate the mass of $$CH_{3}CN $$and $$CH_{3}OH $$using their respective volumes and densities. Next, convert the mass of $$CH_{3}OH to $$moles. The molar mass of $$CH_{3}OH is $$approximately 32.04 g/mol. Divide the mass of $$CH_{3}OH by $$its molar mass to get the number of moles. Molality is defined as the number of moles of solute (in this case, $$CH_{3}OH) $$per kilogram of solvent (in this case, $$CH_{3}CN). $$Convert the mass of $$CH_{3}CN $$from grams to kilograms by dividing by 1000. Finally, calculate the molality by dividing the number of moles of $$CH_{3}OH by $$the mass of $$CH_{3}CN in $$kilograms. This will give you the molality of the solution in mol/kg. Remember that molality is a measure of the concentration of a solution. It tells us how many moles of solute are present in a certain amount of solvent. In this case, it tells us how many moles of methanol are present in a certain amount of acetonitrile.

Ch.13 - Properties of Solutions

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Brown 14th Edition

Ch.13 - Properties of Solutions

문제 49b

13장, 문제 49b

The density of acetonitrile (CH₃CN) is 0.786 g/mL and the density of methanol (CH₃OH) is 0.791 g/mL. A solution is made by dissolving 22.5 mL of CH₃OH in 98.7 mL of CH₃CN. (b) What is the molality of the solution?

검증된 단계별 안내

First, we need to calculate the mass of each component. The mass of a substance can be calculated by multiplying its volume by its density. So, calculate the mass of CH₃CN and CH₃OH using their respective volumes and densities.

Next, convert the mass of CH₃OH to moles. The molar mass of CH₃OH is approximately 32.04 g/mol. Divide the mass of CH₃OH by its molar mass to get the number of moles.

Molality is defined as the number of moles of solute (in this case, CH₃OH) per kilogram of solvent (in this case, CH₃CN). Convert the mass of CH₃CN from grams to kilograms by dividing by 1000.

Finally, calculate the molality by dividing the number of moles of CH₃OH by the mass of CH₃CN in kilograms. This will give you the molality of the solution in mol/kg.

Remember that molality is a measure of the concentration of a solution. It tells us how many moles of solute are present in a certain amount of solvent. In this case, it tells us how many moles of methanol are present in a certain amount of acetonitrile.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Density

Density is defined as mass per unit volume and is typically expressed in grams per milliliter (g/mL) for liquids. It is a crucial property that helps determine how much mass of a substance is contained in a given volume. In this question, the densities of acetonitrile and methanol are provided, which will be used to calculate the mass of each component in the solution.

Molality

Molality is a measure of concentration defined as the number of moles of solute per kilogram of solvent. It is particularly useful in situations where temperature changes may affect volume, as it relies on mass rather than volume. To calculate molality, one must first determine the moles of methanol and the mass of the solvent (acetonitrile) in kilograms.

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is essential for converting between grams and moles when performing calculations in chemistry. In this problem, the molar mass of methanol will be needed to convert the mass of methanol into moles, which is necessary for calculating the molality of the solution.