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Ch.13 - Solutions
Tro - Chemistry: A Molecular Approach 4th Edition
Tro4th EditionChemistry: A Molecular ApproachISBN: 9780134112831당신이 사용하는 게 아니라요?교과서 변경
13장, 문제 71

Calculate the vapor pressure of a solution containing 24.5 g of glycerin (C3H8O3) in 135 mL of water at 30.0 °C. The vapor pressure of pure water at this temperature is 31.8 torr. Assume that glycerin is not volatile and dissolves molecularly (i.e., it is not ionic), and use a density of 1.00 g/mL for the water.

검증된 단계별 안내
1
Calculate the number of moles of glycerin (C3H8O3) using its molar mass. The molar mass of glycerin is calculated by adding the atomic masses of its constituent atoms: 3 carbons (C), 8 hydrogens (H), and 3 oxygens (O).
Determine the mass of water in grams using the given density and volume. Since the density of water is given as 1.00 g/mL, multiply the volume of water (135 mL) by the density to find the mass in grams.
Calculate the number of moles of water using its molar mass. The molar mass of water (H2O) is the sum of the atomic masses of 2 hydrogens and 1 oxygen.
Use Raoult's Law to find the vapor pressure of the solution. Raoult's Law states that the vapor pressure of a solution is equal to the mole fraction of the solvent times the vapor pressure of the pure solvent. Calculate the mole fraction of water by dividing the moles of water by the total moles of the solution (moles of water + moles of glycerin).
Multiply the mole fraction of water by the vapor pressure of pure water at 30.0 °C to find the vapor pressure of the solution.

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주요 개념

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

Vapor Pressure

Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid or solid form at a given temperature. It reflects the tendency of particles to escape from the liquid phase into the vapor phase. In solutions, the presence of a non-volatile solute, like glycerin, lowers the vapor pressure of the solvent compared to its pure state.
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가이드 코스
02:40
Raoult's Law and Vapor Pressure

Raoult's Law

Raoult's Law states that the vapor pressure of a solvent in a solution is directly proportional to the mole fraction of the solvent. This law is crucial for calculating the vapor pressure of a solution when a non-volatile solute is present. It helps determine how the addition of solute affects the overall vapor pressure of the solvent.
추천 영상:
가이드 코스
02:40
Raoult's Law and Vapor Pressure

Mole Fraction

Mole fraction is a way of expressing the concentration of a component in a mixture, defined as the number of moles of that component divided by the total number of moles of all components. In this context, calculating the mole fraction of water in the solution is essential for applying Raoult's Law to find the new vapor pressure after glycerin is added.
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가이드 코스
00:36
Mole Fraction Formula