8 original questions from New Regents. The worksheet, answer key, and browser practice are free.
Conservation of Mass 4 questions
Conservation of Mass
New Regents original practice • Name: ____________________ Date: __________ Show your work for written answers.
In an ordinary chemical reaction, atoms are rearranged and total mass is conserved. Define which substances a measurement includes.
Question 1
A sealed container and its contents have a mass of 150.0 g before a reaction. What mass should the same sealed system have afterward?
- Less than 150.0 g because new substances formed
- 150.0 g
- More than 150.0 g because atoms gained bonds
- Zero if a gas formed
Question 2
Two reactants of 6.0 g and 9.0 g react in a closed model. One product has mass 12.0 g. What is the mass of the other product?
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Question 3
An open flask becomes lighter when a reaction releases a gas. Explain how conservation can still hold.
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Question 4
What happens to the atoms during the chemical reaction?
- They disappear from the entire system.
- They are rearranged among substances.
- They change into different elements.
- They all gain the same mass.
Comparing Container Records 4 questions
Comparing Container Records
Use the information below to answer the questions.
Two model trials start with equal masses of reactants that form a gas. Each table value is the net mass of material included in the measurement. The sealed trial retains its gas, and the open trial allows gas to escape.
| Trial | Starting mass (g) | Final measured mass (g) |
|---|---|---|
| P, sealed | 20.0 | 20.0 |
| Q, open | 20.0 | 17.6 |
Question 5
What accounts for Q’s lower final measured mass under the stated conditions?
- Gas left the measured container.
- Atoms were destroyed in the reaction.
- The sealed trial formed no gas.
- The starting mass was lower in Q.
Question 6
Assuming gas is the only material that leaves Q, calculate its mass.
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Question 7
Describe a measurement change that would allow a test of total mass conservation for Q.
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Question 8
Which sum includes all modeled products of Q?
- 17.6 g only
- 17.6 g plus the escaped gas mass
- 20.0 g plus the escaped gas mass
- 20.0 g minus the sealed trial mass
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