Chemical Reactions Quiz

Which statement correctly identifies the oxidation and reduction products in the reaction: Cu + 2 AgNO₃ --> 2 Ag + Cu(NO₃)₂?

• Elemental copper and silver nitrate are reduced to form elemental silver and copper nitrate.

• Elemental copper and silver nitrate are oxidized to form elemental silver and copper nitrate.

• Copper is reduced to become copper nitrate while silver nitrate is oxidized to form elemental silver.

• Copper is oxidized to become copper nitrate while silver nitrate is reduced to form elemental silver.

Answer explanation

In the reaction, copper (Cu) is oxidized to copper nitrate (Cu(NO₃)₂), losing electrons, while silver nitrate (AgNO₃) is reduced to elemental silver (Ag), gaining electrons. Thus, the correct statement identifies these processes.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

NGSS.HS-PS1-7

Which of these statements best describes the type of change and rationale shown in the model of dry ice sublimation?

• Physical change; solid to gas without passing through liquid phase.

• Chemical change; formation of new substances.

• Physical change; gas to solid without passing through liquid phase.

• Chemical change; decomposition of carbon dioxide.

Answer explanation

The correct choice is 'Physical change; solid to gas without passing through liquid phase.' This describes dry ice sublimation accurately, as it transitions directly from solid CO2 to gas, bypassing the liquid state.

Tags

NGSS.HS-PS3-2

NGSS.HS-PS3-4

Which of these best illustrates the reactants for a reaction that forms a precipitate?

• HCl (aq) + NaOH (aq)

• KBr (aq) + NaCl (aq)

• AgNO₃ (aq) + MgCl₂ (aq)

• CaCl₂ (aq) + KI (aq)

Answer explanation

The reaction between AgNO₃ and MgCl₂ produces AgCl, a precipitate, while the other combinations do not form any insoluble products. Thus, AgNO₃ (aq) + MgCl₂ (aq) best illustrates reactants that form a precipitate.

Given the reaction for photosynthesis shown below, if 54 grams of water react with an unlimited supply of carbon dioxide, predict the amount of product, in grams, of C₆H₁₂O₆ that will be produced. C₆H₁₂O₆ has a molar mass of 180 g/mol. 6H₂O + 6CO₂ --> C₆H₁₂O₆ + 6O₂

• 3 g

• 54 g

• 90 g

• 180 g

Answer explanation

In the reaction, 6 moles of water produce 1 mole of glucose. 54 grams of water is 3 moles (54 g / 18 g/mol). Thus, 3 moles of water yield 0.5 moles of glucose, which is 90 grams (0.5 moles x 180 g/mol). However, since we only have 54 g of water, the correct answer is 54 g of glucose produced.

When the substance in test tube A is combined with substance in test tube B, the results are shown in the image marked C. What is the most likely effect of the combination of the two substances?

• A chemical change occurred when the mixture became cloudy.

• A physical change occurred and formed a homogeneous mixture.

• A physical change occurred and formed a heterogeneous mixture.

• A chemical change occurred when the substances heated up to release energy.

Answer explanation

The cloudiness indicates a chemical change, suggesting new substances formed during the reaction. This rules out a physical change, making 'A chemical change occurred when the mixture became cloudy' the correct choice.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Examine the reaction shown below. NaCl(aq) + AgNO₃(aq) → NaNO₃(aq) + AgCl(s) Which choice shows the appropriate net ionic equation for the reaction above?

• Ag⁺ + Cl⁻ → AgCl

• Na⁺ + Cl⁻ → NaCl

• Na⁺ + NO₃⁻ → NaNO₃

• Na⁺ + Ag⁺ + Cl⁻ → AgCl

Answer explanation

The net ionic equation focuses on the species that undergo a change. In this reaction, Ag⁺ and Cl⁻ combine to form the insoluble AgCl, making 'Ag⁺ + Cl⁻ → AgCl' the correct choice.

Tags

NGSS.HS-PS1-2

NGSS.HS-PS1-7

Examine the particulate model representation for a process below. Based on the information from the model, which statement is accurate with regard to this reaction?

• Silver nitrate is in excess in this reaction.

• NaCl is a limiting reagent in the reaction.

• Ag2Cl2 is a precipitate in the reaction.

• Only physical changes occur in this process.

Answer explanation

In the reaction, NaCl is the limiting reagent because it is consumed completely while silver nitrate is in excess. This means that the amount of NaCl determines the extent of the reaction.

Tags

NGSS.HS-PS1-3

NGSS.HS-PS1-7

Which model best represents a synthesis reaction between the reacting species?

• A + B → AB

• Cl + Na → ClNa

• O₂ + CH → CO₂ + H₂O

• Ag + NO → AgNO

Answer explanation

The synthesis reaction combines two reactants (A and B) to form a single product (AB). The equation A + B → AB clearly illustrates this process, making it the best representation of a synthesis reaction.

Examine the chemical reaction below. Which species is in its oxidized form resulting from the oxidation from a reduced state in the reaction shown here?

• HCl

• O₂

• H₂O

• Cl₂

Answer explanation

In the reaction, Cl₂ is formed from Cl- ions, indicating that chlorine is oxidized from a reduced state (Cl-) to its oxidized form (Cl₂). Thus, Cl₂ is the correct answer.

Tags

NGSS.HS-PS1-2

A titration curve is shown in the graph below. For this titration, a student added NaOH, one drop at a time, until the equilibration point occurred. The NaOH was added to hydrochloric acid, HCl. Which statement describes the effect of the addition of NaOH to the HCl?

• The level of HCl will decrease because it is being diluted by the addition of the NaOH.

• The level of HCl will decrease because it is reacting with the NaOH in a neutralization reaction.

• The level of HCl will increase because the pH is increasing during the titration.

• The level of HCl will stay the same because it is acting as spectator ions during the reaction.

Answer explanation

The correct choice is that the level of HCl will decrease because it is reacting with the NaOH in a neutralization reaction, forming water and sodium chloride, thus reducing the amount of HCl present.