Students apply conservation of mass to explain ash weight, predict mass after a sealed reaction, and classify lemonade as a mixture type. Part B has five fill-in-the-blank problems about mass in closed systems, air as a mixture, and chemical formulas.
Applying conservation of mass to open and closed systems — and classifying matter types in real-world contexts — connects the abstract law to the observable phenomena students encounter in lab investigations and everyday life.
Style:
Properties of Matter
Part A: Multiple Choice
Circle the best answer for each question.
1. A student burns a piece of paper in an open container and finds that the ash weighs less than the original paper. Does this violate conservation of mass?
A) Yes, because mass was clearly lost when the paper burned.
B) No, because the missing mass escaped as gases and smoke into the air.
C) Yes, because chemical changes always reduce the total amount of mass.
D) No, because ash is a different substance so it should weigh less.
2. Before a reaction, the total mass of the reactants is 50 grams. After the reaction in a sealed container, what is the total mass of the products?
A) Less than 50 grams because some mass is converted into energy.
B) Exactly 50 grams because mass is conserved in chemical reactions.
C) More than 50 grams because new substances are created during the reaction.
D) It depends on whether the reaction is physical or chemical.
3. Lemonade is made by mixing water, lemon juice, and sugar. Which classification of matter best describes lemonade?
A) An element because it is a single liquid substance.
B) A compound because the ingredients are chemically combined.
C) A heterogeneous mixture because the sugar sinks to the bottom.
D) A homogeneous mixture because the ingredients are evenly mixed throughout.
4. A student adds 10 grams of baking soda to 20 grams of vinegar in a sealed bag. After the reaction stops and gas fills the bag, what is the total mass?
A) Less than 30 grams because the gas weighs less than the original liquids.
B) Exactly 30 grams because all the matter is still inside the sealed bag.
C) More than 30 grams because the gas takes up more space so it has more mass.
D) It cannot be determined without knowing what products the reaction made.
Part B: Fill in the Blank
Write the correct answer on each line.
1. In a closed system, the total mass stays the same before and after any change.
2. Air is classified as a mixture because it contains several different gases mixed together.
3. H₂O is the chemical formula for water, showing it contains hydrogen and oxygen.
4. When matter seems to disappear during a reaction, it has usually changed into a gas.
5. An element is a pure substance that cannot be broken down into simpler substances.
Properties of Matter
★ Part A: Multiple Choice
Circle the best answer for each question.
1. A student burns a piece of paper in an open container and finds that the ash weighs less than the original paper. Does this violate conservation of mass?
A) Yes, because mass was clearly lost when the paper burned.
B) No, because the missing mass escaped as gases and smoke into the air.
C) Yes, because chemical changes always reduce the total amount of mass.
D) No, because ash is a different substance so it should weigh less.
2. Before a reaction, the total mass of the reactants is 50 grams. After the reaction in a sealed container, what is the total mass of the products?
A) Less than 50 grams because some mass is converted into energy.
B) Exactly 50 grams because mass is conserved in chemical reactions.
C) More than 50 grams because new substances are created during the reaction.
D) It depends on whether the reaction is physical or chemical.
3. Lemonade is made by mixing water, lemon juice, and sugar. Which classification of matter best describes lemonade?
A) An element because it is a single liquid substance.
B) A compound because the ingredients are chemically combined.
C) A heterogeneous mixture because the sugar sinks to the bottom.
D) A homogeneous mixture because the ingredients are evenly mixed throughout.
4. A student adds 10 grams of baking soda to 20 grams of vinegar in a sealed bag. After the reaction stops and gas fills the bag, what is the total mass?
A) Less than 30 grams because the gas weighs less than the original liquids.
B) Exactly 30 grams because all the matter is still inside the sealed bag.
C) More than 30 grams because the gas takes up more space so it has more mass.
D) It cannot be determined without knowing what products the reaction made.
★ Part B: Fill in the Blank
Write the correct answer on each line.
1) In a closed system, the total mass stays the same before and after any change.
2) Air is classified as a mixture because it contains several different gases mixed together.
3) H₂O is the chemical formula for water, showing it contains hydrogen and oxygen.
4) When matter seems to disappear during a reaction, it has usually changed into a gas.
5) An element is a pure substance that cannot be broken down into simpler substances.
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9 Questions
12-18 minutes
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