Chemical Reactions and Stoichiometry Flashcards

In a single replacement reaction, what determines whether the reaction will occur?

Answer: Whether the replacing element is more reactive than the one it displaces

A single replacement reaction occurs only if the replacing element is higher on the activity series than the element it displaces.

What is theoretical yield?

Answer: The maximum amount of product calculated from stoichiometry assuming complete reaction

Theoretical yield is the calculated maximum product possible based on the limiting reagent and stoichiometry.

Which equation is correctly balanced?

Answer: 2H₂ + O₂ → 2H₂O

2H₂ + O₂ → 2H₂O has 4 hydrogen atoms and 2 oxygen atoms on each side, satisfying conservation of mass.

What is the molarity of a solution containing 2 moles of NaCl dissolved in 0.5 liters of solution?

Answer: 4 M

Molarity = moles ÷ liters = 2 mol ÷ 0.5 L = 4 M.

In the reaction 2Al + 3Cl₂ → 2AlCl₃, if 3 moles of Cl₂ are available and 4 moles of Al are available, which is the limiting reagent?

Answer: Cl₂, because it requires a 3:2 ratio with Al and runs out first

3 moles Cl₂ can react with only 2 moles Al (ratio 3:2), leaving 2 moles Al unused; Cl₂ is the limiting reagent.

Which of the following best describes an endothermic reaction?

Answer: It absorbs heat from the surroundings

Endothermic reactions absorb energy (heat) from the surroundings, causing the surroundings to feel cooler.

What is the coefficient of O₂ when the equation _C₃H₈ + _O₂ → _CO₂ + _H₂O is balanced?

Answer: 5

Balanced: C₃H₈ + 5O₂ → 3CO₂ + 4H₂O; five O₂ molecules provide the 10 oxygen atoms needed for 3CO₂ and 4H₂O.