Conservation Of Mass- 8.P.1.4

Which of the following is true about the mass of the reactants in a chemical reaction?

• The total mass of the reactants in a chemical reaction will never be equal to the total mass of the products.

• The total mass of the reactants in a chemical reaction is conserved and will be equal to the total mass of the products.

• The total mass of the reactants in a chemical reaction will be significantly more than the total mass of the products.

• The total mass of the reactants in a chemical reaction will be significantly less than the total mass of the products.

Tags

NGSS.MS-PS1-5

In the chemical reaction below, sodium metal and chlorine gas combine to form sodium chloride.

sodium metal + chlorine gas → sodium chloride (table salt)

If the combined mass of the reactants is 50 grams, then the mass of sodium chloride formed once the reaction has reached completion

• will be exactly 100 grams.

• will be exactly 50 grams.

• will be between 50 and 100 grams.

• will be less than 50 grams.

Tags

NGSS.MS-PS1-5

The balanced equation for the production of sugars by photosynthesis is shown above.

This equation demonstrates the law of conservation of mass because

• there is the same number of compounds on the right side of the equation as the left.

• the sugar molecule on the right has the same mass as the carbon dioxide molecules on the left.

• there are more oxygen atoms on the right side of the equation than on the left.

• there is the same number of each type of atom on the right side of the equation as the left.

Tags

NGSS.MS-LS1-6

NGSS.MS-PS1-5

Twenty-four grams of magnesium metal reacts with sixteen grams of oxygen gas to form magnesium oxide. According to the law of conservation of mass, how much magnesium oxide will there be after the chemical change is complete?

• 40 g

• 8 g

• 32 g

• 74 g

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

A chemical reaction involves the rearrangement of atoms to form new molecules. During a chemical reaction, however, atoms are neither created nor destroyed.

Which of the following is true about the atoms involved in a chemical reaction?

• The total mass of the atoms involved in a chemical reaction will stay the same no matter how the atoms are rearranged.

• The total mass of the atoms involved in a chemical reaction will decrease if two molecules combine to form one single compound.

• The total mass of the atoms involved in a chemical reaction will stay the same no matter how the atoms are rearranged.

• The total mass of the atoms involved in a chemical reaction will increase if a new compound is formed during the reaction.

Tags

NGSS.MS-PS1-5

The chemical reaction shown above takes place in a closed system. What is true about the system while the reaction occurs?

• The total mass of the particles in the system stays the same.

• The total mass of the particles in the system increases.

• The total number of particles in the system decreases.

• The total number of particles in the system increases.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

In atomic theory, new substances are formed when the atoms of other substances are rearranged. In this kind of change, the total number of atoms is conserved.

An example of this is shown in the diagram above. There are six atoms both before and after the arrow.

• The number of substances increases.

• The amount of matter decreases.

• The number of substances is conserved.

• The amount of matter is conserved.

Tags

NGSS.MS-PS1-5

When electricity flows through water, the water molecules split into molecules of hydrogen and oxygen gas. How many oxygen (O₂) molecules are produced from the splitting of two molecules of water (H₂O) if the balanced equation for the reaction is as follows?

2H₂O 2H₂ + O₂

• 2

• 3

• 4

• 1

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-2

NGSS.MS-PS1-5

When solid magnesium burns, it reacts with oxygen in the air to form a powder called magnesium oxide. A chemist performed this reaction in a lab and found that the mass of the magnesium oxide was greater than the mass of the magnesium. What is the reason behind this increase in mass?

• The increase in the mass of the magnesium oxide was due to magnesium atoms in the air.

• The increase in the mass of the magnesium oxide was due to oxygen atoms in the air.

• The increase in the mass of the magnesium oxide happened because oxygen is heavier than magnesium.

• The increase in the mass of the magnesium oxide happened because magnesium is heavier than oxygen.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

When limestone (calcium carbonate) is strongly heated, it breaks down into calcium oxide and carbon dioxide.

If 88 grams of carbon dioxide is released when 200 grams of limestone is heated, how much calcium oxide is produced in this reaction?

• 88 g

• 56 g

• 112 g

• 56 g

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5