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Questions and Answers
What is the molarity of a solution containing 5 g of NaOH in 450 mL?
What is the molarity of a solution containing 5 g of NaOH in 450 mL?
How is molality defined?
How is molality defined?
Why is molarity considered a function of temperature?
Why is molarity considered a function of temperature?
What mass of KCl corresponds to a 1.00 mol kg solution?
What mass of KCl corresponds to a 1.00 mol kg solution?
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What is the molality of 2.5 g of ethanoic acid in 75 g of benzene?
What is the molality of 2.5 g of ethanoic acid in 75 g of benzene?
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How does total vapor pressure over a solution relate to the mole fraction of one component?
How does total vapor pressure over a solution relate to the mole fraction of one component?
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What happens to the total vapor pressure over the solution as the mole fraction of component 2 increases?
What happens to the total vapor pressure over the solution as the mole fraction of component 2 increases?
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Which statement correctly describes the graphical representation of vapor pressure vs. mole fraction?
Which statement correctly describes the graphical representation of vapor pressure vs. mole fraction?
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What could be concluded if the total vapor pressure has a maximum value of $p_2$?
What could be concluded if the total vapor pressure has a maximum value of $p_2$?
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In the context of the solution described, what is indicated by a minimum value of total vapor pressure at $p_1$?
In the context of the solution described, what is indicated by a minimum value of total vapor pressure at $p_1$?
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What does Dalton conclude about the concentration of dissolved gas in a solution?
What does Dalton conclude about the concentration of dissolved gas in a solution?
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In the equation p = KH x, what does KH represent?
In the equation p = KH x, what does KH represent?
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What relationship does Henry's law illustrate?
What relationship does Henry's law illustrate?
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Why do different gases have different KH values at the same temperature?
Why do different gases have different KH values at the same temperature?
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If you were to plot partial pressure versus mole fraction of a gas in solution, what type of graph would you expect?
If you were to plot partial pressure versus mole fraction of a gas in solution, what type of graph would you expect?
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What causes the decrease in the vapour pressure of a solution compared to that of the pure solvent?
What causes the decrease in the vapour pressure of a solution compared to that of the pure solvent?
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How does the addition of non-volatile solutes, like sucrose or urea, affect the vapour pressure of water?
How does the addition of non-volatile solutes, like sucrose or urea, affect the vapour pressure of water?
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According to Raoult's law, the partial vapour pressure of each component in a binary solution is proportional to what?
According to Raoult's law, the partial vapour pressure of each component in a binary solution is proportional to what?
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What is the relationship between the amount of non-volatile solute and the decrease in vapour pressure?
What is the relationship between the amount of non-volatile solute and the decrease in vapour pressure?
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Which statement accurately describes the effect of solute on the solvent's vapour pressure?
Which statement accurately describes the effect of solute on the solvent's vapour pressure?
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What does it indicate when the enthalpy of mixing of two pure components is zero?
What does it indicate when the enthalpy of mixing of two pure components is zero?
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What characterizes a solution that behaves ideally?
What characterizes a solution that behaves ideally?
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Which of the following pairs of substances is likely to form an ideal solution?
Which of the following pairs of substances is likely to form an ideal solution?
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What is the result of a non-ideal solution exhibiting positive deviation from Raoult’s law?
What is the result of a non-ideal solution exhibiting positive deviation from Raoult’s law?
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In terms of volume, what happens when two ideal components are mixed?
In terms of volume, what happens when two ideal components are mixed?
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Which condition defines a non-ideal solution?
Which condition defines a non-ideal solution?
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What kind of deviation occurs when the vapor pressure of a solution is lower than predicted?
What kind of deviation occurs when the vapor pressure of a solution is lower than predicted?
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Which of the following statements is true regarding ideal solutions?
Which of the following statements is true regarding ideal solutions?
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Study Notes
Molarity Calculation
- Molarity (M) is calculated as moles of solute per liter of solution.
- For NaOH, with a mass of 5 g, the number of moles is 0.125 mol using the molar mass of 40 g/mol.
- The volume of the solution is converted from 450 mL to 0.450 L.
- Molarity of the NaOH solution is calculated as 0.125 mol × 1000 mL/L ÷ 450 mL, yielding 0.278 M.
Molality Definition
- Molality (m) is defined as the number of moles of solute per kilogram of solvent.
- A 1.00 mol/kg solution of KCl indicates that 1 mol (74.5 g) of KCl is dissolved in 1 kg of water.
- Molality is independent of temperature, unlike molarity, which is temperature-dependent due to volume change.
Example of Molality Calculation
- For 2.5 g of ethanoic acid (CH3COOH) in 75 g of benzene, the calculation of molality involves determining moles of ethanoic acid and converting the mass of benzene to kg (0.075 kg).
Henry's Law
- Henry’s Law states that the partial pressure of a gas in vapor phase is proportional to its mole fraction in solution, expressed as p = KH x, where KH is the Henry’s law constant.
- The relationship between solubility of gas and partial pressure highlights that different gases have distinct KH values at a given temperature.
Vapor Pressure and Mole Fractions
- Total vapor pressure over a solution is influenced by the mole fraction of components.
- It varies linearly, indicating that as the mole fraction of one component increases, the vapor pressure changes correspondingly.
- The minimal and maximal vapor pressures in a binary solution depend on the volatility of the components.
Raoult's Law
- Raoult’s Law states that the partial vapor pressure of each volatile component is directly proportional to its mole fraction in the solution.
- For ideal solutions, the mixing process leads to no heat absorption or evolution (ΔmixH = 0) and the volume of mixing is negligible (ΔmixV = 0).
- Ideal behavior is observed when intermolecular forces are consistent among A-A, B-B, and A-B types.
Non-Ideal Solutions
- Non-ideal solutions deviate from Raoult’s law under certain concentrations, exhibiting either positive or negative deviations.
- Positive deviation results in higher vapor pressure than predicted by Raoult's law, while negative deviation results in lower vapor pressure.
- Vapor pressure vs. mole fraction plots illustrate these deviations for non-ideal solutions.
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Description
Test your understanding of molarity calculations with this quiz focused on a specific example involving NaOH. You'll work through the process of calculating moles and converting volume to find molarity. Perfect for chemistry students looking to reinforce their knowledge.
