Law of Conservation of Mass

Students react baking soda & vinegar.
Which of the following would provide the evidence that the number of atoms present before a chemical reaction is equal to the number of atoms present after the chemical reaction?

• The mass of the plastic bag, baking soda, and vinegar before the reaction was equal to the mass after the reaction.
• Bubbles were produced during the reaction, which meant that a gas was being produced.
• The plastic bag did not change in any way, indicating that it was not involved in the reaction.
• The mass of the baking soda was exactly equal to the mass of the vinegar used to create the chemical reaction.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

When CaCO₃ is heated, it forms CaO and CO₂. Which of these statements best describes the mass of the products if 100 g of CaCO₃ is heated?

• The difference in the products’ masses is equal to the mass of the CaCO₃
• The sum of the products’ masses is less than the mass of the CaCO₃
• The mass of each product is equal to the mass of the CaCO₃
• The sum of the products’ masses equals the mass of the CaCO₃

Tags

NGSS.MS-PS1-5

Suppose a reaction were to happen in an open container in a lab.  During the reaction, the scientist observes the chemicals bubble, and produce a gas.   During the analysis the scientist notices that the reactants weighed 20 g when he started, and the product weighed 18 g.  Explain what happened.  

• His chemical reaction defied the law of conservation of mass
• The product destroyed mass during the reaction
• The reactants created matter during the reaction
• The gas that was produced was not able to be weighed since the container was open.  

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

If a reaction produces 18 grams, and one of its reactants had 10 grams, how much did the other reactant had?

• 28 grams
• 18 grams
• 10 grams
• 8 grams

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

If a reaction starts with a total 75g of reactants it should produce 

• a total of 40g of products
• a total of 75g of products
• a total of 180 g of products
• None of the above

Tags

NGSS.MS-PS1-5

The total amount of matter (atoms) before and after a chemical reaction (change), remains the same.

• True
• False

Tags

NGSS.MS-PS1-5

Why does this picture demonstrate the Law of Conservation of Mass?

• the number of atoms of each element are the same on both sides

• they start out separate and end up combined

• the same elements are used

• it doesn't demonstrate the Law of Conservation of Mass

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

This type of system allows matter to flow freely in and out...

• Closed System

• Open System

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NGSS.MS-PS1-4

A boiling pot with a lid on it to keep in the energy is what type of system?

• Closed System
• Open System

What is the definition of chemical reaction?

• The input which reacts chemically to create product
• a system where none of the reactants or products are allowed to escape
• occurs when the atoms and molecules of two or more substances rearrange to form new substances
• the output, or result of a chemical reaction

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5