Question 1

A silver solder is to be prepared with an atom ratio of 5.00 Ag : 4.00 Cu : 1.00 Zn. What mass of copper (Cu) should be used to prepare 1.00 kg of this solder? (Atomic masses: Ag = 107.87 u, Cu = 63.55 u, Zn = 65.38 u)

Accepted Answer

$$\displaystyle 254\ \mathrm{g}$$

Question 2

Two compounds of chlorine and element X have the following data: Compound 1: 137 u, 77.5% Cl; Compound 2: 208 u, 85.1% Cl. What is element X?

Accepted Answer

Thallium (Tl)

Question 3

A 0.312 g sample of dimethylhydrazine yields 0.458 g $$\mathrm{CO}_2$$ and 0.374 g $$\mathrm{H}_2\mathrm{O}$$ upon combustion. In a separate experiment, 0.486 g of the compound gives 0.226 g $$\mathrm{N}_2. $$What is the empirical formula of dimethylhydrazine?

Accepted Answer

$$\displaystyle \mathrm{C}_2\mathrm{H}_8\mathrm{N}_2$$

Question 4

In the preparation of azobenzene, 0.10 L of nitrobenzene (density = 1.20 g/mL) and 0.30 L of triethylene glycol (density = 1.12 g/mL) are reacted. If 55 g of azobenzene is obtained, what is the percent yield? (Molar masses: nitrobenzene = 123 g/mol, triethylene glycol = 150 g/mol, azobenzene = 182 g/mol)

Accepted Answer

$$\displaystyle 82\%$$

Question 5

Which of the following nuclei would receive the greatest pairing advantage according to the nuclear pairing model? (Choose from: $$^{16}\mathrm{O}$$, $$^{18}\mathrm{O}$$, $$^{17}\mathrm{O}$$, $$^{18}\mathrm{F})$$

Accepted Answer

$$\$$displaystyle ^{16}$$\mathrm{O}$$

Question 6

A 25.00 mL sample of HCl(aq) is added to 0.10000 g of $$\mathrm{CaCO}_3. $$After reaction, the excess HCl requires 43.82 mL of 0.01185 M $$\mathrm{Ba(OH)}_2 to $$neutralize. What was the molarity of the original HCl(aq)?

Accepted Answer

$$\displaystyle 0.0941\ \mathrm{M}$$

Question 7

A mixture contains only $$\mathrm{CuCl}_2$$ and $$\mathrm{FeCl}_3. A 0.7391 g $$sample requires 86.91 mL of 0.1463 M $$\mathrm{AgNO}_3 to $$precipitate all chloride as $$\mathrm{AgCl}. $$What is the percentage by mass of copper in the mixture? (Atomic masses: Cu = 63.55 u, Fe = 55.85 u, Cl = 35.45 u)

Accepted Answer

$$\displaystyle 42.7\%$$

Question 8

Hydrogen gas reacts with nitrogen gas to form ammonia. If a reaction mixture starts with 3.00 mol $$\mathrm{H}_2$$ and 1.00 mol $$\mathrm{N}_2$$, and 0.400 mol $$\mathrm{N}_2$$ remains after the reaction, how many moles of $$\mathrm{NH}_3$$ are formed?

Accepted Answer

$$\displaystyle 1.80\ \mathrm{mol}$$

Question 9

Which of the following best explains why $$^{16}\mathrm{O} is $$more stable than $$^{17}\mathrm{O} or$$ $$^{18}\mathrm{F}$$ according to the nuclear pairing model?

Accepted Answer

It has an even number of both protons and neutrons, maximizing pairing energy.

Question 10

A chemist wants to prepare 1.00 kg of a solder with a 5:4:1 atom ratio of Ag:Cu:Zn. What is the mass of zinc (Zn) required? (Atomic masses: Ag = 107.87 u, Cu = 63.55 u, Zn = 65.38 u)

Accepted Answer

$$\displaystyle 65.4\ \mathrm{g}$$

Question 11

Given the reaction: $$\mathrm{CaCO}_3(s) + 2\ \mathrm{HCl}(aq) \rightarrow \mathrm{CaCl}_2(aq) + \mathrm{H}_2O(l) + \mathrm{CO}_2(g)$$, what volume of 0.100 M HCl is required to completely react with 2.00 g of $$\mathrm{CaCO}_3$$? (Molar mass $$\mathrm{CaCO}_3 = 100.09\ \mathrm{g/mol})$$

Accepted Answer

$$\displaystyle 0.100\ \mathrm{L}$$

Question 12

A sample of dimethylhydrazine is combusted, producing $$\mathrm{CO}_2$$ and $$\mathrm{H}_2O. $$Which experimental data would you use to determine the empirical formula of the compound?

Accepted Answer

Mass of $$\mathrm{CO}_2$$, mass of $$\mathrm{H}_2O$$, and mass of $$\mathrm{N}_2$$ produced

Question 13

A mixture of $$\mathrm{CuCl}_2$$ and $$\mathrm{FeCl}_3 is $$analyzed by precipitating all chloride ions as $$\mathrm{AgCl}. $$Which of the following best describes the stoichiometry of the precipitation reactions?

Accepted Answer

$$\mathrm{CuCl}_2$$ reacts with 2 mol $$\mathrm{AgNO}_3$$ per mol, $$\mathrm{FeCl}_3$$ reacts with 3 mol $$\mathrm{AgNO}_3$$ per mol

Question 14

If 0.400 mol $$\mathrm{N}_2$$ remains after the reaction $$\mathrm{N}_2 + 3\mathrm{H}_2 \rightarrow 2\mathrm{NH}_3$$ starts with 1.00 mol $$\mathrm{N}_2$$ and 3.00 mol $$\mathrm{H}_2$$, how many moles of $$\mathrm{H}_2$$ remain?

Accepted Answer

$$\displaystyle 0.800\ \mathrm{mol}$$

Question 15

Which of the following is the correct formula for the compound with a molecular mass of 137 u and 77.5% Cl by mass, if the other element is thallium (Tl)? (Atomic masses: Cl = 35.45 u, Tl = 204.38 u)

Accepted Answer

$$\mathrm{TlCl}$$

Question 16

In the reaction $$2\mathrm{C}_6\mathrm{H}_5\mathrm{NO}_2 + 4\mathrm{C}_6\mathrm{H}_{14}\mathrm{O}_4 \rightarrow (\mathrm{C}_6\mathrm{H}_5\mathrm{N})_2 + 4\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_4 + 4\mathrm{H}_2\mathrm{O}$$, what is the limiting reactant if 0.10 L of nitrobenzene (density = 1.20 g/mL) and 0.30 L of triethylene glycol (density = 1.12 g/mL) are used? (Molar masses: nitrobenzene = 123 g/mol, triethylene glycol = 150 g/mol)

Accepted Answer

Triethylene glycol

General Chemistry Problem Set 2 – Step-by-Step Guidance

Guida di studio - Domande di pratica

Study guide - Flashcard