Which is Chemical Equation is Balanced?

Question

Which is Chemical Equation is Balanced?

4Al+3O₂----->2Al₂O₃

CH₄+O₂------>CO₂+2H₂O

H₂+O₂----->2H₂O₄

Answer 1

To determine which chemical equation is balanced, we need to check if the number of atoms of each element on the reactant side (left) is equal to the number on the product side (right).

1. 4Al + 3O₂ → 2Al₂O₃

   • Left: 4 Al, 3 O
   • Right: 4 Al (from 2 Al₂O₃), 6 O (from 2 Al₂O₃)
   • This equation is not balanced (the number of oxygen atoms does not match).

2. CH₄ + O₂ → CO₂ + 2H₂O

   • Left: 1 C, 4 H, 2 O
   • Right: 1 C (from CO₂), 4 H (from 2 H₂O), 3 O (1 from CO₂ and 2 from 2 H₂O)
   • This equation is not balanced (the number of oxygen atoms does not match).

3. H₂ + O₂ → 2H₂O₄

   • Since H₂O₄ is not a standard compound, let's assume you meant H₂O.
   • Left: 2 H, 2 O
   • Right (if it were H₂O): 4 H, 2 O (from 2 H₂O)
   • This equation is also not balanced (the number of hydrogen atoms does not match).

Based on the evaluations, none of the provided equations are balanced. If you meant different products or made a typographical error, please clarify so I can assist you better!

Answer 2

Which is Chemical Equation is Balanced?

Which is Chemical Equation is Balanced?

A. 4Al+3O₂----->2Al₂O₃

B. CH₄+O₂------>CO₂+2H₂O

C. H₂+O₂----->2H₂O₄

Answer 3

Let's evaluate each chemical equation again for balance:

A. \( 4Al + 3O₂ \rightarrow 2Al₂O₃ \)

• Reactants:

  • Aluminum (Al): 4
  • Oxygen (O): \( 3 \times 2 = 6 \)

• Products:

  • Aluminum (Al): \( 2 \times 2 = 4 \)
  • Oxygen (O): \( 2 \times 3 = 6 \)

This equation is balanced.

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B. \( CH₄ + O₂ \rightarrow CO₂ + 2H₂O \)

• Reactants:

  • Carbon (C): 1
  • Hydrogen (H): 4
  • Oxygen (O): \( 2 \)

• Products:

  • Carbon (C): 1 (from CO₂)
  • Hydrogen (H): \( 2 \times 2 = 4 \) (from 2 H₂O)
  • Oxygen (O): \( 1 + 2 = 3 \) (1 from CO₂ and 2 from 2 H₂O)

This equation is not balanced (the number of oxygen atoms does not match).

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C. \( H₂ + O₂ \rightarrow 2H₂O₄ \)

Assuming you meant \( H₂O \) as the product:

• Reactants:

  • Hydrogen (H): 2
  • Oxygen (O): \( 2 \)

• Products (if corrected to H₂O):

  • Hydrogen (H): \( 2 \times 2 = 4 \) (from 2 H₂O)
  • Oxygen (O): \( 2 \) (from 2 H₂O)

This equation is not balanced (the number of hydrogen atoms does not match).

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Conclusion:

The balanced equation is A. \( 4Al + 3O₂ \rightarrow 2Al₂O₃ \).

Answer 4

Which are examples of chemical changes?

A. Alka-Selter in water

B. Boiling water

C. Melting butter

D. Rusting nail

E. Sugar disolving in water

F. Baking a cake

Answer 5

Chemical changes involve a transformation that alters the chemical composition of a substance, resulting in the formation of new substances. Let's evaluate each option:

A. Alka-Seltzer in water – This is a chemical change. When Alka-Seltzer tablets dissolve in water, they undergo a reaction that produces gas (carbon dioxide) and results in new chemical compounds.

B. Boiling water – This is a physical change. Boiling water changes its state from liquid to gas (steam) but does not alter the chemical composition of the water (H₂O).

C. Melting butter – This is a physical change. Melting involves a change of state from solid to liquid but does not change the chemical composition of the butter.

D. Rusting nail – This is a chemical change. Rusting involves the reaction of iron with oxygen and moisture to form iron oxide, which is a new compound.

E. Sugar dissolving in water – This is a physical change. While sugar does dissolve, it retains its chemical identity (C₁₂H₂₂O₁₁), and no new substances are formed.

F. Baking a cake – This is a chemical change. Baking involves a complex series of chemical reactions, including the formation of new substances (like proteins from eggs and caramelization from sugar).

Summary of Chemical Changes:

• Chemical Changes: A, D, F
• Physical Changes: B, C, E

Thus, examples of chemical changes from your list are A, D, and F.

Answer 6

The total amount of matter (atoms) before and after a chemical reaction (change), remains the same.

True

False

Answer 7

True.

This statement reflects the principle of the conservation of mass, which states that in a closed system, the total mass of matter (and hence the total number of atoms) remains constant before and after a chemical reaction. Atoms are neither created nor destroyed in a chemical reaction; they are simply rearranged to form new substances.

Answer 8

Suppose a reaction were to happen in an open container in a lab. During the reaction, the scientist observes the chemicals bubble, and produce a gas. During the analysis the scientist notices that the reactants weighed 20 g when he started, and the product weighed 18 g. Explain what happened.

A. The gas that was produced was not able to be weighed since the container was open.

B. The product destroyed mass during the reaction.

C. This chemical reaction defied the law of conservation of mass.

D. The reactants created matter during the reaction.

Answer 9

The correct explanation for the scenario is:

A. The gas that was produced was not able to be weighed since the container was open.

In an open container, any gas produced during the chemical reaction can escape into the air. Therefore, if the scientist measured the weight of the reactants before the reaction (20 g) and the weight of the products after the reaction (18 g), the difference in weight (2 g) can be attributed to the gas that escaped during the reaction. This scenario does not violate the law of conservation of mass, as the total mass of the system has not changed; it has simply gone into the gaseous state and left the closed system of the weighing.

The other options (B, C, and D) are incorrect because:

• B: The product did not destroy mass; mass is always conserved in a reaction.
• C: The chemical reaction did not defy the law of conservation of mass; it is still upheld. The lost mass corresponds to the mass of the gas that escaped.
• D: The reactants do not create new matter; the apparent loss of mass is due to the escape of gas.

Answer 10

Evidence of a chemical reaction include:

A. bubbles forming

B. Phase change

C. shape change

D. no new substance

Answer 11

The correct option that indicates evidence of a chemical reaction is:

A. bubbles forming

Bubbles forming often signify the production of a gas, which is a common indication of a chemical reaction occurring.

Let's evaluate the other options:

• B. Phase change: Phase changes (like melting, boiling, freezing, etc.) are typically physical changes. While some chemical reactions involve phase changes, a phase change alone does not necessarily indicate a chemical reaction.

• C. Shape change: A change in shape can occur during physical changes or chemical changes but does not serve as definitive evidence of a chemical reaction. For example, breaking or molding substances can change their shape without any chemical alteration.

• D. No new substance: This statement is incorrect regarding chemical reactions. A defining characteristic of a chemical reaction is the production of one or more new substances with different chemical properties from the reactants.

Summary:

The only clear evidence of a chemical reaction from the given options is A. bubbles forming.