Chemistry Chapter on Aqueous Solutions

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Questions and Answers

What is the molarity of a solution containing 1.5 mol of NaCl dissolved in 0.500 L of solution?

3.0 M NaCl (correct)

2.0 M NaCl

4.0 M NaCl

1.0 M NaCl

How do you express the moles of solute when given a mass of 22.4 g of HCl?

0.800 mol HCl

0.125 mol HCl

1.14 mol HCl

0.614 mol HCl (correct)

What is the first step in calculating the molarity of a solution?

Add solvents to the solute.

Dilute the solution with water.

Measure the total volume in milliliters.

Convert mass of solute to moles. (correct)

If 42.23 g of NH4Cl is dissolved to make 500.0 mL of solution, what is necessary to calculate its molarity?

Convert 500.0 mL to liters and calculate moles of NH4Cl. Signup and view all the answers

Why is the term 'aq' sometimes added after a solute in a solution?

To specify that the solvent is water. Signup and view all the answers

Which conversion factor is essential for calculating the number of moles from mass for HCl?

Molar mass of HCl Signup and view all the answers

If you have a solution with a molarity of 0.394 M HCl, how many moles of HCl are in 1.56 L of solution?

0.614 mol HCl Signup and view all the answers

Which of the following is a common misconception about molarity calculations?

The volume of solvent is used instead of the total solution volume. Signup and view all the answers

What is the molarity of a solution containing 53.50 g of NH4Cl in 0.5000 L of solution?

1.579 M NH4Cl Signup and view all the answers

How many moles of NaCl are present in 0.5000 L of a 4.69 M solution?

1.045 moles Signup and view all the answers

If 66.2 g of C6H12O6 is dissolved to make 235 mL of solution, what is its molarity?

1.57 M C6H12O6 Signup and view all the answers

Which of the following correctly describes the relationship of concentration and stoichiometry in a chemical reaction?

Concentration provides a conversion factor between moles of solute and liters of solution. Signup and view all the answers

How would you describe the process of determining the moles of solute given its concentration and volume?

Using the molarity equation. Signup and view all the answers

What is the mass of solute needed to prepare 1.00 L of a 2.00 M NaCl solution?

116.88 g Signup and view all the answers

If 137 g of NaCl is dissolved in 500 mL, what is the concentration in mol/L?

4.69 M NaCl Signup and view all the answers

Which factor is essential when using molarity as a conversion factor?

The units must be consistent. Signup and view all the answers

What is the mass of the solution when 25.0 g of sugar is dissolved in 100.0 g of water?

125.0 g Signup and view all the answers

How is percent by mass calculated in a solution?

Mass of solute divided by total mass of solution times 100% Signup and view all the answers

What is the mass/mass percent concentration of a saline solution with 36.5 g of NaCl in 355 g of solution?

10.3% Signup and view all the answers

To prepare a 5.00% NaCl solution with a total mass of 3000.0 g, what mass of NaCl is needed?

150.0 g NaCl Signup and view all the answers

In a solution prepared using 15.8 g of dextrose in a total mass of 200.0 g, what is the mass/mass percent concentration?

7.90% Signup and view all the answers

If you need to express mass percent as a conversion factor, which of the following is correct?

g solute / 100 g solution Signup and view all the answers

If a solution has a mass of 255 g and 25 g sugar dissolved in it, what would be the percent by mass of sugar?

10.87% Signup and view all the answers

When calculating the amount of solute needed for a specific concentration, what must be known?

The mass of the solution and the desired percent concentration Signup and view all the answers

Study Notes

Chapter Overview

Solutions are crucial in various chemical, biological, and industrial applications.
Aqueous solutions (where substances dissolve in water) are a focus of this chapter.
Solutions can involve all states (gas-gas, solid-solid, liquid-solid, liquid-liquid).
This chapter primarily concentrates on aqueous solutions.

Tragedy in Cameroon - Lake Nyos

In 1986, a gas cloud from Lake Nyos (Cameroon) killed over 1,700 people.
The gas was primarily carbon dioxide, released after a lake overturn.
The carbon dioxide was dissolved in the water and released into the atmosphere.
The incident prompted investigations into other African lakes, specifically Lake Kivu.

Solutions - Homogeneous Mixtures

The major component of a solution is the solvent.
The minor component of a solution is the solute.
The overall phase of a solution is identical to the solvent's phase.
Examples:
- Salt water: solid NaCl in liquid water
- Air: gaseous O2 in gaseous N2
Table 13.2.1 demonstrates various solution types with illustrations.

Like Dissolves Like

Polar compounds dissolve polar compounds.
Nonpolar compounds dissolve nonpolar compounds.
Polar compounds do not dissolve in nonpolar compounds, and vice versa.
This principle is summarized in Table 13.2.2.
Intermolecular forces (London dispersion forces, dipole-dipole interactions, hydrogen bonding) determine solubility.

Solutions of Solids Dissolved in Water

Solubility is the maximum amount of solute that can dissolve in a given amount of solvent at a specific temperature.
A saturated solution is one where the maximum amount of solute is dissolved.
These solutions are saturated or unsaturated.
The solubility of solids typically increases with temperature.
Supersaturated solutions can hold more solute than their saturated counterparts.
Table 13.3.1 lists the solubility of specific ionic compounds.

Electrolyte Solutions

Electrolytes are compounds that yield ions in solution.
Strong electrolytes dissociate nearly completely in solution.
Weak electrolytes dissociate partially.
Nonelectrolytes do not dissociate.
Conductivity measurements can distinguish these types of solutions.
Table 13.3.2 displays conductivity examples.

Solutions of Gases in Water

Gas solubility typically decreases with increasing temperature.
Gas solubility increases with increased pressure.
Thermal pollution (e.g., hot water discharge from industries) can decrease the amount of dissolved oxygen in water, impacting aquatic life.
This is described by Henry's law and Figure 13.4.1.

Specifying Solution Concentration - Mass Percent

Mass percent (%m/m) = (mass of solute / mass of solution) * 100%
Quantitative expressions for solution concentration.
Allows measuring ratios of solute to solution.

Specifying Solution Concentration - Molarity

Molarity (M) = (moles of solute / liters of solution).
A crucial concentration expression for chemical calculations.

Solution Dilution

M1V1 = M2V2.
M1 & M2 represent initial and final concentrations, while V1 & V2 represent initial and final volumes.
Diluting a solution involves adding more solvent without altering the amount of solute.

Solution Stoichiometry

Using concentration to calculate reactant/product amounts in solution-based reactions.

Freezing Point Depression and Boiling Point Elevation

Colligative properties depend on solute concentration.
Freezing point of solutions is lower than the pure solvent.
Boiling point of solutions is higher than the pure solvent.
Formulas for freezing point depression and boiling point elevation involve molality and van't Hoff factor.

Osmosis

Osmosis is the solvent's movement across a semipermeable membrane from a lower to a higher concentration of solute
Osmotic pressure is directly related to solute concentration and is crucial in biological systems.
Osmosis explains why IV fluids must be isotonic to prevent cell damage.

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Description

Explore the crucial role of solutions in chemical, biological, and industrial applications with a focus on aqueous solutions. This chapter delves into the composition of solutions, the impact of a historical tragedy in Cameroon due to gas release, and the fundamental concepts of homogeneous mixtures.