Which of the reactions below are combination, or synthesis, reactions? (A synthesis reaction is where two or more reactants combine to form a single product.)

Answer 1

To determine which reactions are combination or synthesis reactions, we need to identify if two or more reactants combine to form a single product. Here are the reactions:

1) N₂ + 3H₂ → 2NH₃ - This is a combination or synthesis reaction because nitrogen gas (N₂) and hydrogen gas (H₂) react to form ammonia (NH₃).

2) 2H₂ + O₂ → 2H₂O - This is not a combination or synthesis reaction. It is a combustion reaction where hydrogen gas (H₂) and oxygen gas (O₂) react to form water (H₂O).

3) 2Na + Cl₂ → 2NaCl - This is a combination or synthesis reaction because sodium (Na) and chlorine (Cl₂) combine to form sodium chloride (NaCl).

4) Mg + 2HCl → MgCl₂ + H₂ - This is not a combination or synthesis reaction. It is a single displacement or replacement reaction where magnesium (Mg) reacts with hydrochloric acid (HCl) to form magnesium chloride (MgCl₂) and hydrogen gas (H₂).

Therefore, the reactions 1) and 3) are combination or synthesis reactions.