When iron rusts and forms iron oxide, the iron oxide has more mass than the iron. Which statement correctly explains this difference in mass

Question

Responses

The oxygen atoms in iron oxide have more mass than the iron atoms in pure iron.

There are more iron atoms in iron oxide than in pure iron.

The iron atoms in iron oxide have more mass than pure iron.

Iron oxide has oxygen atoms, and pure iron does not.

Answer 1

The correct statement that explains the difference in mass when iron rusts and forms iron oxide is:

Iron oxide has oxygen atoms, and pure iron does not.

This is because when iron reacts with oxygen (usually from the environment), it forms iron oxide (rust). The mass of the resulting iron oxide is greater than that of the original iron because the mass of the oxygen that combines with the iron is added to the mass of the iron.

Answer 2

One molecule of calcium oxide, CaO, and one molecule of carbon dioxide, CO2, combine in a chemical reaction to form one substance. Given that matter is neither created nor destroyed, which chemical formula identifies the product of this reaction
Responses:

Ca2O3

Ca2CO3

CaCO2

CaCO3

Answer 3

The product of the reaction between one molecule of calcium oxide (CaO) and one molecule of carbon dioxide (CO2) is calcium carbonate (CaCO3).

Thus, the correct chemical formula that identifies the product of this reaction is:

CaCO3

Answer 4

Which statement correctly explains why the ashes of burnt paper have less mass than the original paper
Responses:

Other atoms combine with the paper to produce the ash.

Some of the atoms in the paper became gases.

Some of the atoms in the paper are destroyed when it burns.

The ash is created from new atoms that have less mass than the paper.

Answer 5

The correct statement that explains why the ashes of burnt paper have less mass than the original paper is:

Some of the atoms in the paper became gases.

When paper burns, it undergoes a chemical reaction with oxygen in the air, producing gases such as carbon dioxide and water vapor along with the remaining solid ash. The mass of the resulting ashes is less because some of the mass from the original paper has been converted into gas and released into the atmosphere. In accordance with the law of conservation of mass, the total mass of the system remains constant, but the physical form of the matter changes, leading to a reduction in the mass of the solid residues (ash).

Answer 6

It takes 1 molecule of nitrogen and 3
molecules of hydrogen to produce 2
molecules of ammonia using the following formula:
1N2+ 3H2 → 2NH3
Identify which combination of molecules will produce ammonia with no leftovers?
Responses:

8N2 and 4H2

4N2 and 4H2

2N2 and 6H2

5N2 and 6H2

Answer 7

To produce ammonia (NH3) with no leftovers, we need to follow the stoichiometry of the reaction given by the equation:

\[ 1N_2 + 3H_2 \rightarrow 2NH_3 \]

This means that for every 1 molecule of nitrogen (N2), 3 molecules of hydrogen (H2) are required to produce 2 molecules of ammonia (NH3).

To find the combinations that will produce ammonia with no leftovers, we can calculate how many total nitrogen (N2) and hydrogen (H2) molecules are needed based on the required ratios.

1. 8N2 and 4H2:

   • N2: 8 molecules
   • H2 needed: \(8 \times 3 = 24\) molecules H2 (Not enough H2)
   • Not valid.

2. 4N2 and 4H2:

   • N2: 4 molecules
   • H2 needed: \(4 \times 3 = 12\) molecules H2 (Not enough H2)
   • Not valid.

3. 2N2 and 6H2:

   • N2: 2 molecules
   • H2 needed: \(2 \times 3 = 6\) molecules H2 (Just enough)
   • Valid combination, producing \(2 \times 2 = 4\) molecules of ammonia (NH3).

4. 5N2 and 6H2:

   • N2: 5 molecules
   • H2 needed: \(5 \times 3 = 15\) molecules H2 (Not enough H2)
   • Not valid.

The only combination that produces ammonia with no leftovers is:

2N2 and 6H2.

Answer 8

In the equation
2H2+1O2→→2H2O
if you change the 2H2 to 3H2 molecules and balance the equation, identify which statement is correct?
Responses:

Each oxygen molecule will combine with 2 hydrogen molecules with no leftover molecules.

It is not possible to produce water without leftover molecules.

The equation will produce three molecules of water.

The result of the equation will be the same.

Answer 9

Let's first look at the original balanced equation:

\[ 2H_2 + 1O_2 \rightarrow 2H_2O \]

If you change \( 2H_2 \) to \( 3H_2 \), the new unbalanced equation would be:

\[ 3H_2 + O_2 \rightarrow ? \]

Now, to balance the equation, we need to determine how many water molecules (H2O) would be produced.

Starting with 3 molecules of hydrogen (H2):

• Each H2 molecule contains 2 hydrogen atoms, so \( 3H_2 \) provides \( 3 \times 2 = 6 \) hydrogen atoms.
• Each water molecule (H2O) requires 2 hydrogen atoms to form.

To find the number of water molecules produced:

• The number of water molecules that can be formed from 6 hydrogen atoms is \( 6 \div 2 = 3 \) molecules of water (H2O).

In order to have the balanced chemical equation, we also need to ensure that there are enough oxygen atoms. Since each water molecule requires 1 oxygen atom, producing 3 molecules of water will require 3 oxygen atoms. Thus, to balance it, we would also need 1.5 molecules of O2 (since each O2 molecule has 2 oxygen atoms).

The balanced equation would therefore be:

\[ 3H_2 + 1.5O_2 \rightarrow 3H_2O \]

Now, let's evaluate the provided statements:

1. Each oxygen molecule will combine with 2 hydrogen molecules with no leftover molecules.

   • This statement is incorrect because 1.5 O2 molecules are needed to combine with 3 H2 molecules.

2. It is not possible to produce water without leftover molecules.

   • This statement would be correct if you consider that you cannot have half molecules in a practical sense, but the equation can be balanced with fractional coefficients.

3. The equation will produce three molecules of water.

   • This statement is correct as we have established that 3 H2O will be produced.

4. The result of the equation will be the same.

   • This statement is incorrect because changing the number of H2 molecules alters the balancing and the amounts of reactants needed.

The correct statement is:

The equation will produce three molecules of water.