Balancing Chemical Equations Quiz Questions And Answers

1. ______ C + O ______ CO_{2 = 1 2 3}

True

False

False. The chemical equation you provided is unbalanced:

C+O------------>CO2

To balance the equation, you need to ensure that the number of atoms of each element is the same on both sides of the arrow. Here's the balanced equation:

C+O2---------------->CO2

Now, there is one carbon atom on each side, and there are two oxygen atoms on each side, balancing the equation. Therefore, the statement is false (F) when considering the unbalanced equation, but it becomes true (T) after balancing.

Explanation

False. The chemical equation you provided is unbalanced:

C+O------------>CO2

To balance the equation, you need to ensure that the number of atoms of each element is the same on both sides of the arrow. Here's the balanced equation:

C+O2---------------->CO2

Now, there is one carbon atom on each side, and there are two oxygen atoms on each side, balancing the equation. Therefore, the statement is false (F) when considering the unbalanced equation, but it becomes true (T) after balancing.

2. ___ 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 balanced equation for the combustion of methane (CH4) is CH4 + 2O2 --> CO2 + 2H2O. This means that for every molecule of methane, you need two molecules of oxygen to produce one molecule of carbon dioxide and two molecules of water.

Explanation

The balanced equation for the combustion of methane (CH4) is CH4 + 2O2 --> CO2 + 2H2O. This means that for every molecule of methane, you need two molecules of oxygen to produce one molecule of carbon dioxide and two molecules of water.

3. _____NH₃ --> ______N₂ + ______H₂

3 1 2

2 1 3

1 2 3

3 2 1

1 3 2

The given balanced chemical equation represents the reaction between ammonia (NH3) and yields nitrogen gas (N2) and hydrogen gas (H2). The coefficients in front of each compound represent the number of moles of each compound involved in the reaction. In this case, the coefficients are 2, 1, and 3 for NH3, N2, and H2, respectively. This means that for every 2 moles of ammonia, 1 mole of nitrogen gas and 3 moles of hydrogen gas are produced.

Explanation

The given balanced chemical equation represents the reaction between ammonia (NH3) and yields nitrogen gas (N2) and hydrogen gas (H2). The coefficients in front of each compound represent the number of moles of each compound involved in the reaction. In this case, the coefficients are 2, 1, and 3 for NH3, N2, and H2, respectively. This means that for every 2 moles of ammonia, 1 mole of nitrogen gas and 3 moles of hydrogen gas are produced.

4. What law says we must have balanced chemical equations?

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. ______ C + ______ O₂ --> ______ CO₂ Write the correct prefixes below

2 1 1

1 1 1

1 2 1

1 2 3

None of these

The correct answer is 1 1 1. This is because the chemical equation given in the question shows the reaction between a carbon molecule (C) and an oxygen molecule (O2) to form carbon dioxide (CO2). The numbers before each element represent the number of atoms of that element in the equation. In this case, there is 1 carbon atom (C), 1 oxygen atom (O), and 1 oxygen molecule (O2), which contains 2 oxygen atoms.

Explanation

The correct answer is 1 1 1. This is because the chemical equation given in the question shows the reaction between a carbon molecule (C) and an oxygen molecule (O2) to form carbon dioxide (CO2). The numbers before each element represent the number of atoms of that element in the equation. In this case, there is 1 carbon atom (C), 1 oxygen atom (O), and 1 oxygen molecule (O2), which contains 2 oxygen atoms.

7. ______ 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 for the reaction is 2H2S + O2 --> 2H2O + 2S. This means that for every 2 molecules of H2S and 1 molecule of O2, 2 molecules of H2O and 2 molecules of S are produced. Therefore, the correct answer is 2 1 2 2, indicating the number of molecules for each reactant and product in the balanced equation.

Explanation

The balanced equation for the reaction is 2H2S + O2 --> 2H2O + 2S. This means that for every 2 molecules of H2S and 1 molecule of O2, 2 molecules of H2O and 2 molecules of S are produced. Therefore, the correct answer is 2 1 2 2, indicating the number of molecules for each reactant and product in the balanced equation.

8. What would happen if we did not follow the law of conservation of mass when taking apart and then putting together a car for repair?

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. ______NH₃ --> ______NH2 + ______H₂

2 1 3

2 3 1

3 1 2

1 3 2

None of these

The chemical equation "3 NH3 → 2 NH2 + H2" represents the decomposition of ammonia (NH3) into amine (NH2) and hydrogen gas (H2). Three molecules of ammonia break down to yield two molecules of amine and one molecule of hydrogen gas. This reaction is an example of a decomposition reaction, where a compound breaks down into simpler substances under appropriate conditions, such as heat or catalysis.

Explanation

The chemical equation "3 NH3 → 2 NH2 + H2" represents the decomposition of ammonia (NH3) into amine (NH2) and hydrogen gas (H2). Three molecules of ammonia break down to yield two molecules of amine and one molecule of hydrogen gas. This reaction is an example of a decomposition reaction, where a compound breaks down into simpler substances under appropriate conditions, such as heat or catalysis.

10. ______ CH₂O + ______ HCl --> ______ CH₄O + ______ Cl₂

2 1 1 1

1 1 2 1

1 1 1 2

1 2 1 1

The balanced chemical equation for the given reaction is 1 CH2O + 2 HCl -> 1 CH4O + 1 Cl2. This means that for every 1 molecule of CH2O and 2 molecules of HCl, 1 molecule of CH4O and 1 molecule of Cl2 are produced. The answer, 1 2 1 1, represents the stoichiometric coefficients of the reactants and products in the balanced equation.

Explanation

The balanced chemical equation for the given reaction is 1 CH2O + 2 HCl -> 1 CH4O + 1 Cl2. This means that for every 1 molecule of CH2O and 2 molecules of HCl, 1 molecule of CH4O and 1 molecule of Cl2 are produced. The answer, 1 2 1 1, represents the stoichiometric coefficients of the reactants and products in the balanced equation.