DAT - Dental Admission General Chemistry: Stoichiometry Questions and Answers

Question 1

In the complete combustion of butane (C4H10), what is the sum of the stoichiometric coefficients of the reactants and products in the balanced chemical equation?

Accepted Answer

33

Answer

15

Answer

18

Answer

21

Question 2

A compound is found to contain 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. If the molar mass of the compound is approximately 180 g/mol, what is its molecular formula?

Accepted Answer

C6H12O6

Answer

C2H4O2

Answer

CH2O

Answer

C3H6O3

Question 3

Consider the reaction: 2 Al(s) + 6 HCl(aq) → 2 AlCl3(aq) + 3 H2(g). If 10.8 g of aluminum (Al) reacts with 36.5 g of hydrochloric acid (HCl), which of the following statements is correct? (Molar masses: Al = 27.0 g/mol, HCl = 36.5 g/mol)

Accepted Answer

Hydrochloric acid is the limiting reactant, and 0.5 moles of H2 are produced.

Answer

Aluminum is the limiting reactant, and 0.6 moles of H2 are produced.

Answer

Aluminum is the limiting reactant, and 1.0 mole of H2 is produced.

Answer

Both reactants are completely consumed.

Question 4

In a laboratory experiment, the reaction of 32.5 g of zinc with excess hydrochloric acid produced 0.90 g of hydrogen gas. What is the percent yield of hydrogen? The balanced equation is: Zn(s) + 2 HCl(aq) → ZnCl2(aq) + H2(g). (Molar masses: Zn = 65.4 g/mol, H2 = 2.0 g/mol)

Accepted Answer

90.0%

Answer

45.0%

Answer

99.4%

Answer

89.5%

Question 5

Which of the following correctly defines the empirical formula of a compound?

Accepted Answer

The formula representing the simplest whole-number ratio of atoms of each element in the compound.

Answer

The formula that shows the actual number of atoms of each element in a molecule.

Answer

A formula that can only be determined from the molar mass of the compound.

Answer

The formula that illustrates the three-dimensional arrangement of atoms in a molecule.

Question 6

The synthesis of ammonia is represented by the equation: N2(g) + 3H2(g) → 2NH3(g). How many grams of hydrogen gas (H2) are required to produce 68 grams of ammonia (NH3)? (Molar masses: N = 14.0 g/mol, H = 1.0 g/mol)

Accepted Answer

12 g

Answer

6 g

Answer

34 g

Answer

4 g