Conservation of Mass

What is the Law of Conservation of mass?

• Mass is created in a chemical reaction
• Mass is created in a physical change
• New chemicals formed from a chemical reaction have a larger overall mass than the original reactants
• Mass is never created or destroyed

Tags

NGSS.MS-PS1-5

In a reaction A + B ----> C,  reactant A has 5g and product  C has 9g. How many grams does reactant B should have? 

• 4g
• 5g
• 9g
• 14g

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

What is the law of conservation of mass?

• The amount of matter changes when reacted or changed.
• The mass of all reactants are changed during a physical or chemical change
• The mass of the reactants equals the mass of the products
• The mass of the products is different than the mass of the reactants.

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

32 g of Oxygen completely reacts with 8 g of Hydrogen to produce _____ g Water

• 8

• 12

• 24

• 40

Tags

NGSS.MS-PS1-5

Given the balanced equation representing a reaction:

2KClO₃ + energy→2KCl + 3O₂

What is the mass of KCl produced when 24.51 grams of KClO₃ reacts completely to produce 9.60 grams of O₂?

• 5.31 g

• 14.91 g

• 34.11 g

• 43.71 g

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

In a closed system, if you start with 100 grams of reactants, how much product should you expect to have after a chemical reaction has occurred?

• Less than 100 grams

• More than 100 grams

• Exactly 100 grams

• Impossible to determine

Tags

NGSS.MS-PS1-5

Why can mass seem to "disappear" in open systems during a chemical reaction?

• Because mass can be destroyed in an open system.

• Because some products may be gases that escape into the atmosphere.

• Because the Law of Conservation of Mass does not apply in open systems.

• Because the reactants are not fully used up in the reaction.

Tags

NGSS.MS-PS1-5

Why can mass seem to "disappear" in open systems during a chemical reaction?

• Because mass can be destroyed in an open system.

• Because some products may be gases that escape into the atmosphere.

• Because the Law of Conservation of Mass does not apply in open systems.

• Because the reactants are not fully used up in the reaction.

Tags

NGSS.MS-PS1-5

Given the equation representing a reaction:

2H₂(g) + 2NO(g) → N₂(g) + 2H₂O(g)

What is the mass of N₂(g) produced when 1.0 gram of H₂(g) completely reacts with 15.0 grams of NO(g) to produce 9.0 grams of H₂O(g)?

• 7.0 g

• 14.0 g

• 25.0 g

• 28.0 g

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

In the reaction 4Fe + 3O₂ → 2Fe₂O₃, if 112 grams of Fe reacts completely with 48 grams of O₂, what is the mass of Fe₂O₃ produced?

• 160 grams

• 120 grams

• 96 grams

• 64 grams

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2