Chemical Reactions Quiz

Which equation represents a double replacement reaction?

• 2 Na + 2 H₂O → 2 NaOH + H₂

• CaCO₃ → CaO + CO₂

• LiOH + HCl → LiCl + H₂O

• CH₄ + 2 O₂ → CO₂ + 2 H₂O

Answer explanation

The equation LiOH + HCl → LiCl + H₂O represents a double replacement reaction, where the cations and anions exchange partners to form new compounds, specifically a salt and water.

Given the reaction: Mg(s) + 2AgNO₃(aq) → Mg(NO₃)₂(aq) + 2Ag(s) Which type of reaction is represented?

• single replacement

• double replacement

• synthesis

• decomposition

Answer explanation

This reaction is a single replacement reaction because magnesium (Mg) displaces silver (Ag) from silver nitrate (AgNO₃), forming magnesium nitrate (Mg(NO₃)₂) and solid silver. Thus, the correct choice is single replacement.

Base your answer(s) to the following question(s) on the balanced chemical equation below. 2H₂O → 2H₂ + O₂ What type of reaction does this equation represent?

• single replacement

• double replacement

• synthesis

• decomposition

Answer explanation

The equation 2H₂O → 2H₂ + O₂ shows water decomposing into hydrogen and oxygen gases. This is a decomposition reaction, where a single compound breaks down into two or more products.

Given the balanced equation: AgNO₃(aq) + NaCl(aq) → NaNO₃(aq) + AgCl(s) This reaction is classified as

• synthesis

• decomposition

• single replacement

• double replacement

Answer explanation

This reaction is classified as a double replacement because the cations and anions of the reactants exchange partners, forming new products: NaNO₃ and AgCl.

Base your answer(s) to the following question(s) on the information below. Hydrogen peroxide, H₂O₂, is a water-soluble compound. The concentration of an aqueous hydrogen peroxide solution that is 3% by mass H₂O₂ is used as an antiseptic. When the solution is poured on a small cut in the skin, H₂O₂ reacts according to the balanced equation below. 2H₂O₂ → 2H₂O + O₂ Identify the type of reaction represented by the balanced equation.

Answer explanation

The reaction 2H₂O₂ → 2H₂O + O₂ is a decomposition reaction, where hydrogen peroxide breaks down into water and oxygen gas.

In the balanced equation 2Na + 2H₂O → H₂ + 2X, the compound represented by X is

• Na₂O

• Na₂O₂

• NaOH

• NaH

Answer explanation

In the reaction 2Na + 2H₂O, sodium reacts with water to produce hydrogen gas (H₂) and sodium hydroxide (NaOH). Thus, the compound X in the equation is NaOH.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Given the equation: X + Cl₂ → C₂H₅Cl + HCl Which molecule is represented by X?

• C₂H₄

• C₂H₆

• C₃H₆

• C₃H₈

Answer explanation

In the reaction, X must be an alkene that can react with Cl₂ to form an alkyl halide and HCl. C₂H₄ (ethylene) is the only option that fits, as it can react to form C₂H₅Cl and HCl, while the others cannot.

Tags

NGSS.HS-PS1-2

Given the incomplete equation: 4Fe + 3O₂ → 2X Which compound is represented by X?

• FeO

• Fe₂O₃

• Fe₃O₂

• Fe₃O₄

Answer explanation

The reaction 4Fe + 3O₂ → 2X indicates that 4 iron atoms react with 3 oxygen molecules to form 2 units of compound X. Balancing the equation shows that X must be Fe₂O₃, as it contains 2 iron and 3 oxygen atoms.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Given the incomplete equation for the combustion of ethane: 2C₂H₆ + 7O₂ → 4CO₂ + 6____ What is the formula of the missing product?

• CH₃OH

• HCOOH

• H₂O

• H₂O₂

Answer explanation

In the combustion of ethane (C₂H₆), the products are carbon dioxide (CO₂) and water (H₂O). The equation shows 6 missing atoms of hydrogen, which corresponds to 6 molecules of water (H₂O) as the correct product.

Tags

NGSS.HS-PS1-7

Given the balanced equation with an unknown compound represented by X: C₆H₁₂O₆(aq) → 2X + 2CO₂(g) Which compound is represented by X?

• CH₃OH(aq)

• CH₂(OH)₄(aq)

• CH₃CH₂OH(aq)

• CH₂OHCH₂OH(aq)

Answer explanation

The reaction of glucose (C₆H₁₂O₆) typically produces ethanol (C₂H₅OH) and carbon dioxide. Among the options, CH₃CH₂OH(aq) is ethanol, making it the correct representation of compound X.

Tags

NGSS.HS-PS1-7