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Questions and Answers
What is the molarity of a solution if 0.30 moles of NaOH are dissolved in 2.0 L of solution?
What is the molarity of a solution if 0.30 moles of NaOH are dissolved in 2.0 L of solution?
- 0.15 M (correct)
- 1.00 M
- 0.30 M
- 0.60 M
How many grams of NaOH are needed to prepare 2.0 L of a 0.15 M NaOH solution?
How many grams of NaOH are needed to prepare 2.0 L of a 0.15 M NaOH solution?
- 15.0 g NaOH
- 9.0 g NaOH
- 12.0 g NaOH (correct)
- 6.0 g NaOH
What does ppm stand for and how is it commonly expressed in a solution?
What does ppm stand for and how is it commonly expressed in a solution?
- Parts per hundred, equivalent to grams of solute per hundred grams of solution
- Parts per billion, equivalent to grams of solute per billion grams of solution
- Parts per million, equivalent to moles of solute per million liters of solution
- Parts per million, equivalent to grams of solute per million grams of solution (correct)
What is the formula for calculating molarity?
What is the formula for calculating molarity?
If the molecular weight of NaOH is 40.0 g/mol, what is the mass of NaOH needed for a 0.15 M solution in 2000 mL?
If the molecular weight of NaOH is 40.0 g/mol, what is the mass of NaOH needed for a 0.15 M solution in 2000 mL?
What is the concentration of NaCl in blood serum expressed in molarity?
What is the concentration of NaCl in blood serum expressed in molarity?
How is concentration expressed in parts per billion (ppb)?
How is concentration expressed in parts per billion (ppb)?
What total volume of solution contains 2.0 g of NaCl if the concentration is 0.14 M?
What total volume of solution contains 2.0 g of NaCl if the concentration is 0.14 M?
If you have a 6.0 M acetic acid solution, how much of this solution is needed to prepare 200 mL of a 3.5 M solution?
If you have a 6.0 M acetic acid solution, how much of this solution is needed to prepare 200 mL of a 3.5 M solution?
What happens to the number of moles of solute after diluting a solution?
What happens to the number of moles of solute after diluting a solution?
Which of the following formulas correctly represents weight/volume percent (w/v) concentration?
Which of the following formulas correctly represents weight/volume percent (w/v) concentration?
What is the primary reason water is an effective solvent for ionic compounds?
What is the primary reason water is an effective solvent for ionic compounds?
What is the primary effect of pressure on the solubility of solids in liquids?
What is the primary effect of pressure on the solubility of solids in liquids?
In the reaction of sodium chloride dissolving in water, what does the term 'hydration' refer to?
In the reaction of sodium chloride dissolving in water, what does the term 'hydration' refer to?
What is observed when heating a hydrated salt like CuSO4·5H2O?
What is observed when heating a hydrated salt like CuSO4·5H2O?
Which concentration expression is most appropriate for very dilute solutions less than 0.1%?
Which concentration expression is most appropriate for very dilute solutions less than 0.1%?
In calculating parts per million (ppm), which of the following is used?
In calculating parts per million (ppm), which of the following is used?
Which statement correctly describes cations in an electrolyte solution?
Which statement correctly describes cations in an electrolyte solution?
What is the unit of molarity?
What is the unit of molarity?
Which of the following correctly describes a 0.1% solution in decimal form?
Which of the following correctly describes a 0.1% solution in decimal form?
What does a 40% volume/volume (v/v) solution mean?
What does a 40% volume/volume (v/v) solution mean?
In percent weight/weight (w/w), what is the ratio calculated?
In percent weight/weight (w/w), what is the ratio calculated?
Which of the following terms refers to concentrations less than 0.1% expressed in relation to a million?
Which of the following terms refers to concentrations less than 0.1% expressed in relation to a million?
Flashcards
Molarity
Molarity
A way to express the concentration of a solution by indicating the number of moles of solute dissolved in one liter of solution.
Moles of solute
Moles of solute
The number of moles of a substance present in a given volume of solution.
Liters of solution
Liters of solution
The total volume of the solution, expressed in liters.
Moles of solute calculation
Moles of solute calculation
Calculated by multiplying the molarity of the solution by the volume of the solution.
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Preparing a solution
Preparing a solution
To prepare a solution with a specific molarity, you need to dissolve the calculated amount of solute in a specific volume of solvent.
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Molecular weight
Molecular weight
The mass of one mole of a substance.
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Alternate molarity equation
Alternate molarity equation
A one-step calculation for molarity using mass of solute, molecular weight, and volume of solution.
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Volume from concentration and mass
Volume from concentration and mass
Finding the volume of a solution needed to contain a specific amount of solute.
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Solubility
Solubility
The amount of solute that can dissolve in a given amount of solvent at a specific temperature.
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Pressure and Solubility
Pressure and Solubility
Pressure has little effect on the solubility of liquids or solids in each other. However, the solubility of a gas in a liquid increases as pressure increases.
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Percent Composition (w/v)
Percent Composition (w/v)
The amount of solute per unit volume of solution. Commonly expressed as weight of solute per volume of solution (w/v).
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Percent Composition (w/w)
Percent Composition (w/w)
The amount of solute per total weight of solution. Similar to w/v but uses weight of solution instead of volume.
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Percent Composition (v/v)
Percent Composition (v/v)
The amount of solute per volume of solution. Expressed as volume of solute per volume of solution (v/v).
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Parts Per Million (ppm)
Parts Per Million (ppm)
A way to express concentration for very dilute solutions, typically less than 0.1%. It represents the amount of solute per million parts of solution.
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Parts Per Thousand (ppt) & Parts Per Million (ppm)
Parts Per Thousand (ppt) & Parts Per Million (ppm)
The decimal equivalent of a small percent concentration. It's used for extremely dilute solutions.
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Units in ppm
Units in ppm
Units used in ppm can be either w/w, w/v, or v/v. Ensure the units for solute and solution are the same.
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What is molarity?
What is molarity?
A method for expressing the concentration of a solution, defined as the number of moles of solute dissolved in one liter of solution. It is represented by the symbol 'M' and expressed as 'moles/liter'.
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What is dilution?
What is dilution?
A process where a solution is made less concentrated by adding more solvent, usually water. The number of moles of solute remains the same, but the total volume of the solution increases.
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What is the dilution equation?
What is the dilution equation?
A mathematical relationship that describes the conservation of moles during dilution. It states that the product of initial molarity (M1) and initial volume (V1) is equal to the product of final molarity (M2) and final volume (V2). This equation can be used to calculate the amount of solvent needed for dilution.
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What is water of hydration?
What is water of hydration?
The attraction between ions and water molecules is so strong that water molecules become part of the crystal structure of many solid compounds. These water molecules are called water of hydration.
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What is dissolving?
What is dissolving?
The process by which a substance dissolves in a solvent, typically water. In the case of ionic compounds, water molecules surround the ions, attracting them and breaking them apart from the crystal lattice.
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What are electrolytes?
What are electrolytes?
Charged particles (ions) in a solution that can move freely and conduct electricity. When an ionic compound dissolves in water, the ions become free to move and conduct.
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What is dehydration?
What is dehydration?
The process by which a hydrated salt loses its water of hydration when heated. The salt loses its crystalline water molecules and becomes anhydrous, resulting in a change in color or physical appearance.
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What is a standard solution?
What is a standard solution?
A solution where the concentration of dissolved substance is known and can be used as a reference standard. It typically has a high concentration and is typically used to prepare other solutions of a desired concentration.
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Solutions and Colloids
- Solutions are homogeneous mixtures
- Solvent is the dissolving medium (usually liquid)
- Solute is the substance dissolved (usually solid)
- Various types of solutions exist (gas in liquid, liquid in liquid, etc.)
- Solutions are uniform in particle distribution
- Solutions do not separate on standing
- Solutions cannot be separated by filtration
- Solutions can have varying compositions
- Solutions are transparent (but can be colored)
- Separating solutions into pure components is a physical change
Solubility
- Solubility is the maximum amount of a solute that dissolves in a given amount of solvent at a specified temperature
- Solubility for solids is a physical constant
- Different solids have different solubilities in various liquids
- Solids with low solubility are called insoluble
- Solids with high solubility are called soluble
Solubility of Liquids
- Some liquids are insoluble in each other (immiscible)
- Examples: gasoline and water; oil and vinegar
- Some liquids have limited solubility in each other (miscible)
- Example: ether in water (6 g/100 g H₂O)
- Other liquids are completely soluble in each other (completely miscible)
- Example: ethanol and water
Concentration Terms
- Dilute solution: a solution with a small amount of solute
- Concentrated solution: a solution with a large amount of solute
- These definitions are not precise
Concentration Terms (More Specific)
- Saturated solution: contains the maximum amount of solute that can dissolve at equilibrium at a given temperature
- Unsaturated solution: contains less than the maximum amount of solute
- Supersaturated solution: contains more solute than the maximum amount possible at a given temperature; excess solute will precipitate if disturbed
Parts Per Million (ppm)
-
Used to express very dilute solutions
-
Calculated by dividing the amount of solute by the amount of solution, and multiplying by one million
-
0.1% solution = 0.001
-
0.0001 % solution = 1 ppm
Molarity
- Molarity (M): moles of solute per liter of solution.
- Example calculation: preparing 2.0 liters of 0.15 M NaOH solution involves determining the required moles of NaOH and converting them to grams
- Molarity = (grams of solute / molecular weight of solute) × 1000/mL of solution.
- In problems involving molarity, convert volumes to liters.
Molarity-Dilution
- For solutions undergoing dilution: M₁V₁ = M₂V₂ (M₁ = initial molarity; V₁ = initial volume; M₂ = final molarity; V₂ = final volume)
Water as a Solvent
- Water dissolves ionic compounds due to its polarity
- Negative ions are attracted to the positive end of water molecules
- Positive ions are attracted to the negative end of water molecules
- Ions surrounded by water molecules are called hydrated
- Water of hydration occurs when the attraction between ions and water molecules is strong enough to be part of the crystal structure
Electrolytes
- Electrolytes conduct electric current when dissolved in water due to ion migration.
- Strong electrolytes fully dissociate into ions
- Weak electrolytes partially dissociate into ions
- Nonelectrolytes do not dissociate into ions
Colloids
- A colloid is a solution in which the solute particles have a diameter between 1 nm and 1000 nm
- Colloid particles exhibit the Tyndall effect (scatter light)
- Colloids are stable and do not settle out.
Tyndall Effect
- Light scattering is characteristic of colloids
- Diffused light is visible in colloidal mixtures, making them appear cloudy
Brownian Motion
- Random motion of colloid-size particles in solution
- This motion is due to collisions with the solvent particles
Colligative Properties
- Depend on the number of solute particles, not their nature
- Include freezing-point depression and boiling-point elevation.
Freezing-Point Depression
- One mole of any solute particle dissolved in 1000 grams of water lowers the freezing point by 1.86°C
- The amount of depression depends on the number of particles, not the identity
Boiling-Point Elevation
- One mole of any solute particle dissolved in 1000 grams of water raises the boiling point by 0.52°C
- Similar to freezing-point depression, the elevation depends on the number of particles
Constants for Depression and Elevation
- Each solvent has unique freezing-point depression and boiling-point elevation constants
Osmosis
- Movement of solvent through a semipermeable membrane from a region of lower solute concentration to a region of higher solute concentration
- Osmotic pressure is the pressure needed to prevent osmosis
- Osmolarity is the molarity multiplied by the number of particles produced by each formula unit
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