WorksheetsUnit 5 - Physical & Chemical Changes (ECOMM)
Total questions: 18
Worksheet time: 2hrs 30mins
Which of the following is an example of a physical change?
A glass in the kitchen breaks.
Apples brown when they are left on the counter.
Logs burn in the fireplace.
Milk sours in the refrigerator.
Which of the following is true about the situations?
All of the situations are examples of physical changes because they are reversible.
None of the situations are examples of physical changes because all involve a color change.
Situation 2 is a physical change because rust forming is a natural process.
Situations 1 and 3 are physical changes because no new substances are formed.
Iron filings are mixed with sand in a bowl. Which of the following is the most effective way to separate the mixture to demonstrate that a physical change has occurred?
Add water to the bowl. The sand will dissolve in water, and the iron filings will be left.
Place the contents of the bowl into a funnel made of filter paper, and use water to separate the sand from the iron filings.
Pour the contents of the bowl into a pot with boiling water. The sand will rise, leaving the iron filings at the bottom of the pot.
Use a magnet to attract the iron filings so that they can be separated from the sand.
Suppose 15 grams of table salt and 15 grams of sand are mixed together. Both dry materials are mixed with 100 mL of water in a glass beaker. Which of the four students explains effective methods to separate the mixtures and draws appropriate conclusions about whether physical or chemical changes have occurred?
Student A: “I noticed that the table salt dissolved in the water. This shows evidence that a chemical change occurred between the salt and water because there is no way to reverse this action. The sand did not dissolve in water. This shows evidence of a physical change because I can separate the sand from the water by using my hands.”
Student B: “The table salt dissolved in the water, and the sand did not. However, the table salt is still there. To prove this, I can use filter paper to separate the sand from the saltwater solution. Then, I can boil the water to evaporate it so that only salt is left in the bottom of the glass beaker. All are examples of physical changes because they can be reversed.”
Student C: “When the salt and sand were added to the water, a color change occurred. The water became cloudy. A color change shows evidence that chemical changes occurred. Therefore, the changes cannot be reversed. The cloudy water shows a new substance was produced.”
Student D: My observations show that the table salt dissolved in water. Once something dissolves, you can no longer see it, so this shows evidence for a chemical change. The sand can be separated from the water. I can pour the sand and water mixture into a flat pan and place it outside in the sun. The water will evaporate leaving only the sand. Because both can be separated from each other again, mixing sand with water is a physical change.”
A student notices a pile of ice on the sidewalk before school. At lunch time, the student returned and the pile of ice had completely melted into a puddle. What is the best argument for what happened to the ice?
The ice lost heat throughout the day as the sun became more direct, causing it to melt into a liquid.
The ice gained heat throughout the day as the sun became more direct, causing it to melt into a liquid.
The ice gained heat throughout the day as the sun became more direct, causing it to evaporate into water vapor.
The ice lost heat throughout the day as the sun became more direct, causing it to evaporate into water vapor.
Which of the following is NOT an appropriate argument for how temperature affects the particles in water?
As heat is added to water, the particles become “excited” and move faster. This can cause a solid to melt into a liquid, or a liquid to evaporate into water vapor.
As heat is removed from water, the particles slow down and become more compact. This can cause water vapor to condense into liquid water, or liquid water to freeze into ice.
As heat is added to water, the particles move slower and sit closer together. This can cause water vapor to condense into liquid water, or liquid water to freeze into ice.
As the temperature of water changes, the speed of the water particles also changes. Slower moving particles that are closer together would exist in ice. Faster moving particles that are free moving and further apart would exist in water or ice.
Which of the following situations does not show evidence of a chemical change?
A gallon of milk goes sour in the refrigerator.
A match lights when it is struck at a party.
A silver necklace becomes tarnished over time.
An aluminum can is crushed on the sidewalk.
Which of the following student observations shows evidence that a chemical change has occurred?
Student A notices that hydrogen peroxide bubbles when it is placed on a cut.
Student B watches as water evaporates from a puddle on his street.
Student C observes that sugar dissolves in her tea.
Student D sees glass glow red hot as it is molded at a glassblowing shop.
Three students at Winterville Elementary were given an assignment by their science teacher to plan and carry out experiments where chemical changes would occur. Below, you can see each student’s plan and the results he or she recorded.
What is true about the students’ experiments?
Student A was the only one to create an experiment where a color change occurred. This shows evidence of a chemical change.
Student A, Student B, and Student C all created experiments where chemical changes occurred. Student A observed a color change, Student B saw bubbles, and Student C was able to dissolve salt.
Student B and Student C created experiments were chemical changes occurred. Student A just dyed her water. Student B and Student C both changed their substances to prove that they had chemical changes. Student B created a gas while Student C got rid of the salt.
Student B was the only one to create an experiment with evidence of a chemical change. She created a new substance, a gas.
In four different investigations, 25 mL of a mystery colorless liquid was mixed with 25 mL of four liquid substances labeled A-D in test tubes. Observations are recorded below. Which student draws appropriate conclusions from the results?
Student W: “A chemical change did not occur in investigations 2 and 3 because temperature changes did not occur.” Chemical changes occurred in investigation 1 because the temperature increased and in investigation 4 because the temperature decreased.
Student X: “Only investigations 1 and 2 showed evidence of chemical changes. In investigation 1, a color change happened. In investigation 2, a gas was created.”
Student Y: “Investigations 1, 2, and 3 showed evidence of chemical changes. A color change in investigation 1 showed that a chemical change occurred. Something new was produced in investigations 2 and 3 to show that a chemical change occurred. Investigation 4 did not show evidence of a chemical change because the mixed liquids stayed colorless.”
Student Z: “Investigations 2 and 3 had new substances that were created, so they showed evidence of chemical changes. Investigation 1 showed evidence of a chemical change due to a color change and an increase in temperature. Investigation 4 also showed evidence of a chemical change because a reaction caused the temperature to decrease.”
Student A places two clear colored liquids into a beaker, places it in the freezer and records his/her observations. Which of the following observations would NOT be something the student could use as an indicator of a chemical change?
An unexpected color change
The presence of a gas or bubbles
An increase in temperature
A change of state
Which of the following would result in a chemical change?
Leaving a metal nail in a jar of water over a period of weeks.
Running a piece of paper through a paper-shredder.
Whisking an egg into a bowl.
Ice decreasing in temperature and melting into a liquid.
Which of the following is an example of a physical change?
A change in the state of water from a liquid to ice
A decrease in temperature when two clear substances are mixed
A piece of cake being digested
An iron nail rusting
Adriana made lemonade outside on a hot summer day. She placed 20 ice cubes in her pitcher to make the lemonade cold. Over time, she observed the temperature of her lemonade.
Which explanation is true about what she noticed?
Adriana’s observations show evidence of a chemical change because there was an increase in temperature.
Adriana’s observations show evidence of a chemical change because the ice dissolved in the water.
Adriana’s observations show evidence of a physical change because changes in the state of water are due to temperature differences.
Adriana’s observations show evidence of a physical change because the ice reacted with the water to raise the temperature.
A group of students recorded the following observations when a colorless liquid was mixed with four other substances, labeled A-D. What conclusions can they draw from the results?
When mixed with the colorless liquid, substances A, B, and C went through chemical changes.
When mixed with the colorless liquid, substances A, B, and D went through chemical changes.
When mixed with the colorless liquid, substances C and D went through chemical changes.
When mixed with the colorless liquid, substances A, B, C, and D went through chemical changes.
Observations for four different investigations are shown in the data table above. What conclusions can you draw from these observations?
Chemical changes occurred in investigations 1 and 4 because new substances were created. Physical changes occurred in investigations 2 and 3 because no new substances were made.
Chemical changes occurred in investigations 2 and 4 because there were temperature changes. Physical changes occurred in investigations 1 and 3 because the temperature did not change.
Chemical changes occurred in investigations 1, 2, 3, and 4 because new substances were created or destroyed.
Chemical changes occurred in investigations 1, 2, and 4 because new substances were created. A physical change occurred in Investigation 3 because this type of change can be reversed.
A student has designed an investigation to determine if placing cake batter into the microwave will result in a chemical change or a physical change. The student’s observations are recorded above:
The student claims that based on his/her evidence, a chemical change has not taken place.
Which of the following statements about the student’s investigation is correct?
The student carried out an investigation that proved that the change was physical since there was no color change.
The student carried out an investigation that proved that a chemical change occurred because there was a change in temperature.
The student carried out an investigation that proved that a chemical change occurred because there was a change in state.
The student did not prove whether this change was chemical or physical based on the evidence, and should collect more data about whether the change was reversible and/or created a new substance.
A student placed a piece of ice into a bucket and left it out in the sun. The student then returned to record the observations. What evidence might the student use to defend whether a chemical or a physical change has occurred?
The student should report that a physical change has occurred because even though the temperature has changed, the change did not result in a new substance being created.
The student should report that a chemical change has occurred because the ice began at a different temperature than the resulting water. A temperature change is the indicator that proves a chemical change has occurred.
The student should report that a physical change has occurred because the ice began at a different temperature than the resulting water. A temperature change is the indicator that proves a physical change has occurred.
The student should report that a chemical change has occurred because the state of the substance changed from a solid to a liquid. If a substance changes state, it has created a new substance, and it indicated a chemical change.
