Chemical Reactions and Stoichiometry Flashcards

In stoichiometry, a mole ratio is obtained from:

Answer: The coefficients of a balanced chemical equation

Mole ratios come directly from the coefficients in a balanced equation and are used to convert between moles of different substances.

Which symbol in a chemical equation indicates that a gas is produced?

Answer: (g) or ↑

The symbol (g) or an upward arrow (↑) indicates a gaseous product is released from the reaction.

For the reaction N₂ + 3H₂ → 2NH₃, if 6 moles of H₂ are used, how many moles of NH₃ are produced?

Answer: 4 moles

The ratio of H₂ to NH₃ is 3:2, so 6 moles H₂ × (2 mol NH₃ / 3 mol H₂) = 4 moles NH₃.

What does a catalyst do in a chemical reaction?

Answer: Speeds up the reaction without being consumed

A catalyst lowers activation energy and speeds up a reaction but is not consumed and does not change the products.

Which of the following correctly represents a precipitation reaction?

Answer: AgNO₃ + NaCl → AgCl↓ + NaNO₃

When AgNO₃ and NaCl solutions are mixed, AgCl forms as an insoluble precipitate (↓) that settles out.

The empirical formula of a compound shows:

Answer: The simplest whole-number ratio of atoms in the compound

The empirical formula gives the simplest ratio of atoms; for example, H₂O₂ has the empirical formula HO.

How many grams of O₂ (molar mass = 32 g/mol) are needed to produce 88 g of CO₂ (molar mass = 44 g/mol) from the reaction C + O₂ → CO₂?

Answer: 64 g

88 g CO₂ ÷ 44 g/mol = 2 moles CO₂; ratio is 1:1, so 2 moles O₂ × 32 g/mol = 64 g O₂.