Chemical Reactions and Stoichiometry Flashcards

What is a limiting reagent in a chemical reaction?

Answer: The reactant that is completely consumed first and stops the reaction

The limiting reagent is consumed first and determines the maximum amount of product that can form.

Balance the equation: _Fe + _O₂ → _Fe₂O₃. What are the correct coefficients?

Answer: 4, 3, 2

4Fe + 3O₂ → 2Fe₂O₃ balances with 4 iron and 6 oxygen atoms on each side.

In a double replacement reaction AB + CD → AD + CB, what happens?

Answer: Two ionic compounds exchange partners

Double replacement reactions involve two ionic compounds swapping their cations or anions with each other.

The percent yield of a reaction is calculated as:

Answer: (actual yield / theoretical yield) × 100

Percent yield = (actual yield ÷ theoretical yield) × 100, showing efficiency of the reaction.

How many molecules are in 1 mole of any substance?

Answer: 6.02 × 10²³

One mole contains 6.02 × 10²³ particles, known as Avogadro's number.

Which of the following reactions is a combustion reaction?

Answer: C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

Combustion involves a hydrocarbon reacting with oxygen to produce CO₂ and H₂O; propane burning is a clear example.

If you have 0.5 moles of CaCl₂ (molar mass = 111 g/mol), what is its mass?

Answer: 55.5 g

Mass = 0.5 mol × 111 g/mol = 55.5 g.