States of Matter
Which state of matter has a definite shape and definite volume?
Solid
Which of the following will float in water: a cork, a rock, or an iron nail?
Cork
Is chocolate milk an example of a pure substance, homogeneous mixture, or heterogeneous mixture?
Heterogeneous mixture (if the chocolate settles) or homogeneous mixture (if mixed evenly).
True or False: Water (H₂O) is an element.
False its a compound
If you mix lemonade powder into water and it dissolves evenly, what kind of solution do you have?
An aqueous solution, because the solvent is water.
Why do gases expand to fill their containers, while solids do not?
Gas particles move freely and spread apart; solid particles are tightly packed in fixed positions.
If an object floats in oil but sinks in water, what can you infer about its density compared to both liquids?
Its density is greater than oil but less than water.
Explain why lemonade made with sugar dissolves evenly, while a salad with lettuce, tomatoes, and cucumbers does not form a uniform mixture.
Lemonade is a homogeneous mixture (solution), while salad is a heterogeneous mixture where parts remain distinct.
If the Earth rotates once every 24 hours, what does this rotation cause?
Day and night
You stir sugar into your tea and all of it dissolves. You add more and it sinks to the bottom without dissolving. What type of solution do you now have?
A saturated solution.
Compare the kinetic energy of particles in solids, liquids, and gases.
Solids = low kinetic energy; Liquids = medium kinetic energy; Gases = high kinetic energy.
A wooden block has a mass of 120 g and a volume of 200 mL. Calculate its density. Will it float or sink in water?
Density = 120 ÷ 200 = 0.6 g/mL
less than 1.0 g/mL → it floats.
A student mixes food coloring with water and observes that the mixture looks the same throughout. What kind of mixture is this, and why?
Homogeneous mixture (solution), because the composition is uniform.
What is the lightest element on the periodic table?
Hydrogen
A block of wood floats in water but sinks in rubbing alcohol. What does this tell you about the wood’s density compared to both liquids?
The wood is less dense than water (so it floats) but more dense than rubbing alcohol (so it sinks).
During boiling, liquid water becomes steam. Explain what happens to the motion and energy of the particles during this process.
The particles gain kinetic energy, move faster, and spread apart as they change into a gas.
A scientist drops a piece of wax (density 0.9 g/mL) into an unknown liquid. The wax floats. Then, the scientist drops a plastic cube (density 0.7 g/mL) into the same liquid, and it sinks.
What can you conclude about the density of the unknown liquid?
The liquid’s density must be between 0.7 g/mL and 0.9 g/mL. (It is more dense than wax, so wax floats, but less dense than the plastic cube, so the cube sinks.)
A student adds instant coffee to hot water and stirs. After a few moments, the liquid is uniform with no visible particles remaining. How would you classify this type of solution? (name all that apply)
It is a homogeneous, aqueous, unsaturated solution.
What planet is known as the “Red Planet”?
Mars
Why do particles in a liquid move faster than those in a solid but slower than those in a gas?
Because liquids have more kinetic energy than solids but less than gases.
A scientist places dry ice (solid carbon dioxide) on a table and notices it changes directly into gas without becoming liquid.
What is this process called?
The process is sublimation.
A piece of metal weighs 250 g and displaces 30 mL of water when submerged. Calculate its density and determine whether it would float or sink in mercury (density 13.6 g/mL).
Density = 250 ÷ 30 = 8.33 g/mL → less than mercury → it floats in mercury.
Describe how you could use evaporation and filtration together to separate a mixture of salt, sand, and water into its original components.
First filter the sand from the saltwater; then evaporate the water, leaving behind the salt.
A metal spoon is left in a pot of hot soup. After a few minutes, the handle of the spoon feels hot too. What type of heat transfer is happening?
Conduction — heat moves through the solid spoon from hot to cool areas.
Two liquids are poured into a beaker: oil (0.9 g/mL) and corn syrup (1.3 g/mL). A plastic bead with a density of 1.0 g/mL is dropped in. Where will the bead settle, and why?
The bead will sink through the oil but float on top of the corn syrup, because its density is between the two.