Conservation of Mass and Chemical Equation Concepts

Question 1

A 24.3 g sample of magnesium is heated in an open crucible until it reacts completely to form magnesium oxide. If the final mass of magnesium oxide is 40.3 g, which statement best explains this observation in the context of the law of conservation of mass?

Accepted Answer

Oxygen from the air combined with magnesium, increasing the total mass of the solid product.

Answer

The law of conservation of mass does not apply to reactions in an open system.

Answer

Magnesium oxide is denser than magnesium, so its mass appears greater.

Answer

Some magnesium was lost as gas during heating, leading to an apparent mass gain.

Question 2

When the following chemical equation is balanced with the smallest whole number coefficients, what is the sum of the coefficients for all reactants and products? C₃H₈(g) + O₂(g) → CO₂(g) + H₂O(l)

Accepted Answer

13

Answer

11

Answer

15

Answer

16

Question 3

Consider the reaction: 2Na(s) + Cl₂(g) → 2NaCl(s). If 46 grams of sodium (Na, molar mass = 23 g/mol) react completely with an excess of chlorine gas (Cl₂, molar mass = 71 g/mol), what mass of sodium chloride (NaCl, molar mass = 58.5 g/mol) is produced?

Accepted Answer

117 g

Answer

58.5 g

Answer

23.0 g

Answer

71 g

Question 4

Calcium carbonate (CaCO₃) decomposes into calcium oxide (CaO) and carbon dioxide (CO₂) when heated. If this reaction occurs in an open system, and 100 g of CaCO₃ produces 56 g of CaO, what apparent mass change would be observed for the solid materials remaining in the container, and why?

Accepted Answer

An apparent mass loss because CO₂ gas escapes the system.

Answer

An apparent mass gain because oxygen is absorbed from the air.

Answer

No change in mass, as mass is always conserved in chemical reactions.

Answer

The mass would fluctuate due to changes in atmospheric pressure.

Question 5

Which of the following symbol equations correctly represents the reaction: 'Aqueous sulfuric acid reacts with solid aluminum hydroxide to form aqueous aluminum sulfate and liquid water'?

Accepted Answer

3H₂SO₄(aq) + 2Al(OH)₃(s) → Al₂(SO₄)₃(aq) + 6H₂O(l)

Answer

H₂SO₄(aq) + Al(OH)₃(s) → Al₂(SO₄)₃(aq) + H₂O(l)

Answer

2H₂SO₄(aq) + Al(OH)₃(s) → AlSO₄(aq) + 3H₂O(l)

Answer

H₂SO₄(aq) + Al(OH)₃(s) → AlSO₄(aq) + H₂O(l)

Game Settings

Game Settings Dino

Play With Friends Dino

Game Settings

Play With Friends

Game Settings

Conservation of Mass and Chemical Equation Concepts

Popular Questions InConservation of Mass and Chemical Equation Concepts

Similar Quizzes

Dr. Doe's Chemistry Quiz

Dr. Doe’s Chemistry Quiz

Dr. Doe's Chemical Quiz

Periodic Table of Elements Quiz

Can You Ace This Dr. Doe's Chemistry Quiz?

Acids, Bases and Salts Quiz

Periodic Table Quiz

Chemistry Quiz

Chemistry Lab Equipment Quiz

The Acid-Base Challenge

Chemistry Quest

Atom,Elements and Compound Quiz