BMST Chemical Reactions and Stoichiometry 2

Question 1

In the reaction 2H₂ + O₂ → 2H₂O, how many moles of water are produced from 4 moles of H₂?

Accepted Answer

4 moles

Answer

The molar ratio of H₂ to H₂O is 1:1, so 4 moles of H₂ produce 4 moles of H₂O.

Question 2

Which type of reaction involves a single compound breaking down into two or more simpler substances?

Accepted Answer

Decomposition

Answer

Decomposition reactions break one compound into simpler products, such as 2H₂O → 2H₂ + O₂.

Question 3

What is the molar mass of CO₂? (C=12, O=16)

Accepted Answer

44 g/mol

Answer

CO₂ has one carbon (12) and two oxygens (2×16=32), giving 12+32=44 g/mol.

Question 4

In a chemical equation, what does the law of conservation of mass require?

Accepted Answer

The number of atoms on both sides must be equal

Answer

Conservation of mass means atoms are neither created nor destroyed, so both sides must have the same number of each type of atom.

Question 5

How many grams of NaCl (molar mass = 58.5 g/mol) are in 2 moles of NaCl?

Accepted Answer

117 g

Answer

Mass = moles × molar mass = 2 × 58.5 = 117 g.

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