Solution Evidence
In salt water, identify the solvent and the solute.
Water is the solvent; salt is the solute.
Water evaporates from a sports drink, but none of the solute leaves. What happens to the concentration?
The concentration increases.
Salt B dissolves at a rate of 54 grams per 100 grams of water at 80°C. How much can dissolve in 200 grams of water?
108 grams.
Temperature remains constant while pressure increases and volume decreases. Name the gas law.
Boyle’s law.
A gas at 1.0 atmosphere occupies 60 milliliters. At constant temperature, it is compressed to 30 milliliters. What is the new pressure?
2.0 atmospheres.
Two clear solutions look identical. One conducts electricity strongly. What is the strongest conclusion supported by this evidence?
The conducting solution contains mobile charged particles, usually ions.
Why does crushed sugar usually dissolve faster than an equal mass of sugar in one cube?
Crushing increases the surface area, allowing more solute particles to collide with water at once.
A saturated Crystal A solution cools from 80°C to 40°C. How many grams crystallize per 100 grams of water?
56 grams because the capacity falls from 100 grams to 44 grams.
Pressure remains constant while a gas is heated and expands. Name the gas law.
Charles’s law.
At constant pressure, a 2.0-liter gas at 300 Kelvin is heated to 450 Kelvin. What is the new volume?
3.0 liters.
A mixture stays uniform, does not settle, and passes through ordinary filter paper. What type of mixture is it?
A solution, or homogeneous mixture.
Cup A contains 5 grams of solute in 100 milliliters of water. Cup B contains 15 grams in 100 milliliters. Which cup is more concentrated, and why?
Cup B because it contains more solute in the same amount of water.
Salt C dissolves at a rate of 39 grams per 100 grams of water at 80°C. How much can dissolve in 250 grams of water?
97.5 grams.
A sealed, rigid tank is heated, causing its pressure to increase. Name the gas law.
Gay-Lussac’s law.
A gas in a rigid container has a pressure of 100 kilopascals at 280 Kelvin. It is heated to 350 Kelvin. What is the new pressure?
125 kilopascals.
Salt water and sugar water are both clear. Which test would provide the best evidence that one contains mobile ions?
A controlled conductivity or resistance test.
Stirring made sugar disappear sooner. What did this experiment prove, and what did it not prove?
It proved that stirring increased the dissolving rate. It did not prove that stirring increased solubility.
At 60°C, all 90 grams of Crystal A are dissolved in 100 grams of water. Classify the solution and calculate how far it is above the stable limit.
It is supersaturated and contains 22 grams more than the stable limit.
A weather balloon rises into an area of lower external pressure and expands while temperature remains constant. Name the gas law.
Boyle’s law.
To test how temperature affects gas pressure, what type of container should be used, and which two conditions must remain constant?
A sealed, rigid container should be used. Volume and the number of gas particles must remain constant.
A student says, “This liquid is clear, so it must be pure.” Correct the student’s claim.
Clear appearance does not prove purity because a homogeneous solution can contain dissolved solute.
Design a fair test of how water temperature affects dissolving time. Name at least three variables that must remain constant.
Possible controls include solute mass, water volume, particle size, stirring, container type, and timing method.
At 100°C, compare Crystal A and Salt B in 300 grams of water. How many more grams of Crystal A can dissolve?
237 grams more. Crystal A dissolves 420 grams, while Salt B dissolves 183 grams.
A flexible balloon cools at constant pressure and becomes smaller. Name the law and describe what happens to particle speed.
Charles’s law; the particles move more slowly.
A student model shows gas particles becoming larger when the gas is heated. Correct the model and explain why pressure increases in a rigid container.
The particles remain the same size but move faster, striking the container walls more often and with greater force.