Question

ii: write the correct answer in the blank.

1. what unit is equivalent to avogadros number of objects?
2. what is a set of symbols that tells how many of each type of atom are found in a molecule?
3. what is the sum of the atomic masses of all the atoms in a molecule?
4. n₂h₄ (hydrazine) is sometimes used as a rocket fuel because it reacts readily with oxygen - containing compounds to produce large amounts of hot gas; one such reaction is 2 n₂h₄(l) + n₂o₄(l) → 3 n₂(g) + 4 h₂o(g). if 3 mol n₂h₄ and 4 mol n₂o₄ are available at the beginning of this reaction, which substance will be the limiting reactant?

Explanation:

• For question 26: Avogadro's number of objects is equivalent to one mole.
• For question 27: A chemical formula is a set of symbols that tells how many of each type of atom are found in a molecule.
• For question 28: The sum of the atomic masses of all the atoms in a molecule is called the molecular mass.
• For question 29:
• According to the reaction equation \(2N_2H_4(l)+N_2O_4(l)\to3N_2(g) + 4H_2O(g)\), the mole ratio of \(N_2H_4\) to \(N_2O_4\) is \(2:1\).
• If we have \(3\space mol\space N_2H_4\), the amount of \(N_2O_4\) required for complete reaction of \(N_2H_4\) is \(\frac{3}{2}=1.5\space mol\). But we have \(4\space mol\space N_2O_4\).
• If we consider \(N_2O_4\), the amount of \(N_2H_4\) required for complete reaction of \(N_2O_4\) is \(2\times4 = 8\space mol\). But we only have \(3\space mol\space N_2H_4\). So \(N_2H_4\) is the limiting reactant.

Answer:

1. mole
2. chemical formula
3. molecular mass
4. \(N_2H_4\)