Mixture Basics & Definitions
Question: What type of mixture has uniform composition throughout, where you cannot distinguish its different components?
Answer: What is a homogeneous mixture (or solution)?
Question: Name three common methods you can use to speed up the rate at which a solid solute dissolves in a liquid solvent.
Answer: What are Agitation (stirring), increasing temperature, and crushing/grinding (increasing surface area)?
Question: What is the basic formula used to calculate the concentration of a solution?
Answer: What is Concentration = Mass of Solute / Volume of Solution (or Volume of Solvent)?
Question: What term describes the maximum mass of solute that can dissolve in a given volume of solvent at a specific temperature?
Answer: What is solubility?
Question: On a standard solubility curve graph, what variable is plotted on the x-axis and what variable is on the y-axis?
Answer: What is Temperature on the x-axis and Solubility (g of solute per 100 cm³ or 100 g of water) on the y-axis?
Question: In a solution made by dissolving sugar in water, what role does the water play?
Answer: What is the solvent?
Question: Why does crushing a solute into smaller pieces make it dissolve faster?
Answer: What is increasing the surface area exposed to the solvent, allowing more collisions between particles?
Question: If 15 g of salt is dissolved in 100 mL of water, what is the concentration in g/mL?
Answer: What is 0.15 g/mL? (15 g / 100 mL)
Question: What will happen if you add one extra crystal of solute to a saturated solution at constant temperature?
Answer: What is the crystal will not dissolve and will settle at the bottom?
Question: On a solubility graph, what do points located directly on the line represent?
Answer: What are saturated solutions?
Question: Define a solute and give one everyday example.
Answer: What is the substance that gets dissolved in a solvent? (Example: salt, sugar, powder drink mix).
Question: How does heating a solvent increase the speed at which a solid solute dissolves?
Answer: What is giving solvent particles more kinetic energy, making them move faster and collide with the solute more frequently and aggressively?
Question: A student dissolves 40 g of solute into 200 cm³ of water. What is the concentration in g/cm³?
Answer: What is 0.2 g/cm³? (40 g / 200 cm³)
Question: What is a supersaturated solution?
Answer: What is a solution that holds more dissolved solute than it normally can at a given temperature
Question: If a point for a solution lies below its solubility curve line, what state is the solution in?
Answer: What is an unsaturated solution?
Question: How does an unsaturated solution differ from a saturated solution?
Answer: What is: an unsaturated solution can dissolve more solute at a given temperature, whereas a saturated solution holds the maximum amount of solute possible at that temperature?
Question: Does stirring a solution increase the maximum amount of solute that can dissolve in a liquid, or only the speed at which it dissolves?
Answer: What is only the speed (rate)? (Stirring does not increase the total solubility).
Question: You have a 0.5 g/mL salt solution. How many grams of salt are contained in 250 mL of this solution?
Answer: What is 125 g? (0.5 g/mL x 250 mL)
Question: What technique is commonly used to create a supersaturated solution in a laboratory setting?
Answer: What is dissolving solute in hot solvent until saturated, and then cooling it slowly without disturbing it?
Question: Based on the solubility graph on Page 22, as temperature increases from 20°C to 80°C, does the solubility of sodium nitrate (NaNO3) increase, decrease, or stay the same?
Answer: What is increase
Question: What is the term for a mixture where visible particles remain suspended or settle out over time, and is it homogeneous or heterogeneous?
Answer: What is a suspension (or heterogeneous mixture)?
Question: How does temperature affect the dissolving rate of gases in liquids compared to solids in liquids?
Answer: What is gas solutes dissolve slower (and become less soluble) as temperature increases, whereas solid solutes generally dissolve faster and become more soluble?
Question: Solution A contains 30 g of sugar in 150 mL of water. Solution B contains 50 g of sugar in 200 mL of water. Which solution is more concentrated?
Answer: What is Solution B? (Solution A = 0.20 g/mL, Solution B = 0.25 g/mL).
Question: If you drop a small seed crystal into a supersaturated solution, what rapid physical change will you observe?
Answer: What is rapid crystallization (the excess solute suddenly precipitates out of solution as solid crystals)?
Question: According to the graph on Page 22, if 100 cm³ of water saturated with potassium nitrate (KNO3) at 60°C is cooled down to 20°C, what will happen to the extra solute?
Answer: What is it will precipitate (crystallize) out as solid crystals because its solubility decreases at lower temperatures?