PHASE CHANGES IN MATTER
What phase change happens when liquid water turns into ice?
Freezing
Breaking a pencil into two pieces is what type of change?
Physical change
A mixture in which all parts look the same is called a __________.
Homogenous mixture
A magnet is used to separate iron fillings from sand. What is this type of separation technique?
Magnetic separation
Which of these is a mixture?
A. Oxygen
B. Pure gold
C. Air
D. Distilled water
C. Air
What is the process called when liquid water changes into water vapor?
Evaporation
Rust forming on an iron nail is what type of change?
Chemical change
Oil and water form what type of mixture?
Which method separates salt from saltwater?
Saltwater
Which of the following is NOT a method of separating mixtures?
A. Filtration
B. Winnowing
C. Evaporation
D. Decantatism
D. Decantatism
What phase change occurs when candle wax near the flame changes from solid to liquid?
Melting
Which is evidence that a chemical change has occurred?
A. Change in shape
B. Formation of gas bubbles
C. Cutting paper
D. Melting ice
B. Formation of gas bubbles
Which mixture is homogeneous?
A. Fruit salad
B. Saltwater
C. Sand and gravel
D. Cereal and milk
B. Saltwater
Which method is best for separating sand from water?
Filtration
Which pair contains one physical change and one chemical change?
A. Melting ice and burning paper
B. Rusting iron and frying an egg
C. Breaking glass and tearing paper
D. Boiling water and freezing water
A. Melting ice and burning paper
A bottle of cold juice is taken out of the refrigerator. After a few minutes, water droplets form on the outside of the bottle. Which phase change caused this?
Condensation
Cooking an egg is considered a chemical change because—
A. it changes shape only
B. it forms a new substance
C. it melts
D. it can be reversed
B. it forms a new substance
Why is fruit salad considered a heterogeneous mixture?
Because its components can be easily seen and separated.
A farmer removes spoiled tomatoes from fresh tomatoes by hand. Which separation method is used?
Handpicking
Which statement is TRUE?
A. Melting is a chemical change.
B. Burning wood is a physical change.
C. Condensation changes gas into liquid.
D. Heterogeneous mixtures always look the same.
C. Condensation changes gas into liquid.
A wet shirt dries while hanging under the sun. Which phase change is taking place? Explain what happens.
Evaporation. The liquid water gains heat from the surroundings and changes into water vapor.
A student dissolves sugar in water and later recovers the sugar by evaporation. Was dissolving sugar a physical or chemical change? Explain.
Physical change because no new substance was formed.
A student tears paper into small pieces and then burns them. Which activity is a physical change, and which is a chemical change? Explain.
Tearing paper is a physical change because no new substance is formed. Burning paper is a chemical change because new substances (ash and smoke) are produced.
You have a mixture of rice, iron nails, and flour. Describe the order of methods you would use to separate all three materials.
Magnetic separation to remove the nails, then sieving or handpicking to separate the rice from the flour.
Read the statements below.
Which statement is incorrect? Correct it.
Statement 1 is incorrect. It should be:
"Melting ice is a physical change."