Balancing Chemical Equations Quiz

1. Evaluate the statement below and select True or False: "___ C + O → ___ CO₂ = 1 2 3 is a correctly balanced equation."

True

False

The unbalanced form C + O → CO₂ is incorrect because carbon dioxide requires two oxygen atoms, not one.

The correct balanced equation is:

C + O₂ → CO₂.

Therefore, the statement is false.

Explanation

The unbalanced form C + O → CO₂ is incorrect because carbon dioxide requires two oxygen atoms, not one.

The correct balanced equation is:

C + O₂ → CO₂.

Therefore, the statement is false.

2. Balance the following chemical equation by choosing the correct set of coefficients: ___ CH₄ + ___O₂ --> ___CO₂ + ___H₂O

1 2 1 2

2 1 2 1

3 1 2 4

1 2 3 4

4 3 1 2

The combustion of methane balances as:

CH₄ + 2O₂ → CO₂ + 2H₂O.

One carbon atom and four hydrogen atoms must appear on both sides. Using a coefficient of 2 for O₂ provides the four oxygen atoms needed to form one CO₂ and two H₂O molecules.

Explanation

The combustion of methane balances as:

CH₄ + 2O₂ → CO₂ + 2H₂O.

One carbon atom and four hydrogen atoms must appear on both sides. Using a coefficient of 2 for O₂ provides the four oxygen atoms needed to form one CO₂ and two H₂O molecules.

3. Select the set of coefficients that correctly balances the decomposition of ammonia: ___ NH₃ → ___ N₂ + ___ H₂

3 1 2

2 1 3

1 2 3

3 2 1

1 3 2

The balanced equation is:

2 NH₃ → N₂ + 3 H₂.

Two ammonia molecules supply the two nitrogen atoms needed for N₂ and six hydrogen atoms, which form three H₂ molecules.

Explanation

The balanced equation is:

2 NH₃ → N₂ + 3 H₂.

Two ammonia molecules supply the two nitrogen atoms needed for N₂ and six hydrogen atoms, which form three H₂ molecules.

4. Which scientific law requires chemical equations to be balanced?

The law of constant attention

The law of constant comments

The second law of thermodynamics

The law of conservation of mass

The rule of law

The law of conservation of mass states that mass cannot be created or destroyed in a chemical reaction, but can only be rearranged. This means that the total mass of the reactants must be equal to the total mass of the products in a balanced chemical equation. This law is essential in chemistry as it helps to ensure that chemical reactions are accurately represented and that the amount of each element is conserved throughout the reaction.

Explanation

The law of conservation of mass states that mass cannot be created or destroyed in a chemical reaction, but can only be rearranged. This means that the total mass of the reactants must be equal to the total mass of the products in a balanced chemical equation. This law is essential in chemistry as it helps to ensure that chemical reactions are accurately represented and that the amount of each element is conserved throughout the reaction.

5. Balancing a chemical equation involves adjusting coefficients to ensure that the number of atoms of each element is the same on both sides of the equation.

True

False

Balancing a chemical equation is the process of adjusting the coefficients (numbers in front of chemical formulas) to achieve equality of the number of atoms for each element on both sides of the equation. This ensures the law of conservation of mass is upheld, where mass is neither created nor destroyed in chemical reactions. By balancing, the quantities of reactants and products are matched, reflecting the precise chemical composition and proportion of substances involved in the reaction.

Explanation

Balancing a chemical equation is the process of adjusting the coefficients (numbers in front of chemical formulas) to achieve equality of the number of atoms for each element on both sides of the equation. This ensures the law of conservation of mass is upheld, where mass is neither created nor destroyed in chemical reactions. By balancing, the quantities of reactants and products are matched, reflecting the precise chemical composition and proportion of substances involved in the reaction.

6. Identify the correct coefficients that balance the formation of carbon dioxide: ___ C + ___ O₂ → ___ CO₂

2 1 1

1 1 1

1 2 1

1 2 3

None of these

The equation balances as:

C + O₂ → CO₂.

One carbon atom reacts with one oxygen molecule to produce one carbon dioxide molecule, with all atoms conserved.

Explanation

The equation balances as:

C + O₂ → CO₂.

One carbon atom reacts with one oxygen molecule to produce one carbon dioxide molecule, with all atoms conserved.

7. Select the correct coefficients that balance the reaction between hydrogen sulfide and oxygen: ___ H₂S + ___ O₂ → ___ H₂O + ___ S

2 1 2 2

2 2 1 2

2 2 2 1

1 2 2 2

3 1 2 2

The balanced equation is:

2 H₂S + 1 O₂ → 2 H₂O + 2 S.

Two molecules of hydrogen sulfide supply enough sulfur and hydrogen atoms to form two sulfur atoms and two water molecules.

Explanation

The balanced equation is:

2 H₂S + 1 O₂ → 2 H₂O + 2 S.

Two molecules of hydrogen sulfide supply enough sulfur and hydrogen atoms to form two sulfur atoms and two water molecules.

8. What would happen if the law of conservation of mass were ignored when taking apart and reassembling a car?

We would have extra pieces left over at the end.

Something would fall off the car soon enough.

A fuel leak might leave a trail of gasoline along the highway.

The car might blow up.

All of the above.

If we did not follow the law of conservation of mass when taking apart and then putting together a car for repair, all of the above consequences would occur. Not conserving mass means that we would not properly account for all the parts and materials of the car, resulting in extra pieces left over at the end. This could lead to something falling off the car soon enough. Additionally, not properly handling the fuel system during repair could cause a fuel leak, leaving a trail of gasoline along the highway. Finally, if the car is not reassembled correctly, there is a risk of a major malfunction or explosion, causing the car to blow up.

Explanation

If we did not follow the law of conservation of mass when taking apart and then putting together a car for repair, all of the above consequences would occur. Not conserving mass means that we would not properly account for all the parts and materials of the car, resulting in extra pieces left over at the end. This could lead to something falling off the car soon enough. Additionally, not properly handling the fuel system during repair could cause a fuel leak, leaving a trail of gasoline along the highway. Finally, if the car is not reassembled correctly, there is a risk of a major malfunction or explosion, causing the car to blow up.

9. Choose the correct coefficients that balance this ammonia decomposition equation: ___ NH₃ → ___ NH₂ + ___ H₂

2 1 3

2 3 1

3 1 2

1 3 2

None of these

The balanced equation is:

3 NH₃ → 2 NH₂ + H₂.

Three NH₃ molecules provide the atoms needed to form two NH₂ units and one H₂ molecule. This reaction represents ammonia breaking down into amine (NH₂) and hydrogen gas.

Explanation

The balanced equation is:

3 NH₃ → 2 NH₂ + H₂.

Three NH₃ molecules provide the atoms needed to form two NH₂ units and one H₂ molecule. This reaction represents ammonia breaking down into amine (NH₂) and hydrogen gas.