Chem Exam 1 Questions

What is the charge on the thallium ion in Tl₂O₃?

+3

Liquid nitrogen boils at 77 K. What is this temperature in °F?

-321°F

If the molar concentration of sodium sulfate (Na₂SO₄) is 0.10 M, what is the concentration of sodium ion?

0.10 M

You are given a 12.5 M stock solution of sodium chloride. You measure 2.5 mL of the stock solution, then you add 125 mL of H₂O. What is the concentration of your new standard solution?

0.25 M

The densities of ethylene glycol and of mercury are 1.11 and 13.5 g/mL, respectively. What volume of mercury has the same mass as 125 mL ethylene glycol?

10.3 mL

What is the molecular mass of potassium carbonate?

138.2 g/mol

Han purple, a synthetic inorganic pigment devleoped in China in ancient times, has the chemical formula BaCuSi₂O₆. What is its percent by mass silicon?

15.9%

If the following arithmetic operations are carried out, how many significant figures should be reported in the answer? 132 + 0.56 + 0.01 + 3.33

3

Sulfuric acid reacts with a vanadium oxide compound according to the following unbalanced reaction. What are the coefficients in the balanced chemical equation in the order in which it is written? H₂SO₄(aq) + V₂O₃(s) → V₂(SO₄)₃(s) + H₂O(l)

3, 1, 1, 3

How many atoms of carbon are present in a 3.25 carat diamond? (0.200 g = 1 carat)

3.26 * 10²²

TNT, or trinitrotoluene, has the chemical formula C₇H₅N₃O₆. How many grams of nitrogen are present in 25 grams TNT (227.13 g/mol)?

4.6 grams

The Vince Lombardi trophy is given to the winner of the Super Bowl. Assuming the trophy is made of pure silver and has a rectangular shape measure approximately 22 inches x 4.5 inches x 3.0 inches, how much silver is needed to make the four (4) trophies that the Green Bay Packers have won? The molar mass of silver is 107.87 g/mol, the density of silver is 10.5 g/cm³, 1 in = 2.54 cm, and 1 kg = 2.20 lb.

450 lb

Gallium has two naturally occurring isotopes with the following masses and natural abundances. Calculate the average atomic mass of Ga. ⁶⁹Ga → 68.9256 amu → 60.108% ⁷¹Ga → 70.9247 amu → 39.892%

69.723 amu

Lead levels in drinking water should be no higher than 15 ppb. What is this in mol/L? Assume the density of drinking water 1.0 g/mL.

7.2 * 10⁻⁸ M

A salt solution is added to a marine aquarium. What mass of sodium chloride (NaCl, 58.44 g/mol) is needed to produce 250.0 mL of a solution that has a concentration of 50.0 mM?

731 mg

What are the group names for the elements Rb, Ca and Br, respectively?

Alkali metals, alkaline earth metals, halogens

What is the empirical formula for a compound that is 92.24% C and 7.76% H?

CH

Nicotine, an alkaloid in the nightshade family of plants that is mainly responsible for the addictive nature of cigarettes, contains 74.02% C, 8.710% H, and 17.27% N. If the molar mass of nicotine is 162.3 g/mol, what is its molecular formula?

C₁₀H₁₄N₂

The mass of 0.25 mol of some element is 8.0 g. What is the diatomic element?

O₂

Table sugar (sucrose, C₁₂H₂₂O₁₁) dissolves in water. This process is what kind of change?

Physical

Which subatomic particles have approximately equal masses?

Protons and neutrons

Which of the following is NOT an element? a) CO b) Cf c) Ts d) At e) Tb

a) CO

Solid carbon dioxide (CO₂) can undergo sublimation to form gaseous CO₂. Which of the following statements is true? a) The motion of the CO₂ molecules in the solid phase is much more restricted than in the gas phase. b) In the solid phase, CO₂ molecules easily slip past each other and there are areas of randomly ordered molecules. c) The CO₂ molecules decompose to form carbon and oxygen when they enter the gas phase. d) CO₂ molecule sin the solid phase are easily compressed to smaller volumes. e) In the gas phase, CO₂ molecules are strongly attracted to each other.

a) The motion of the CO₂ molecules in the solid phase is much more restricted than in the gas phase.

Which statement regarding Rutherford's nuclear model of the atom is false? a) The nucleus contains a tightly packed core of electrons. b) Electrons and protons are not mixed uniformly throughout the atom c) The diameter of the atom is approximately 10,000 times larger than the nucleus d) The atom is mostly empty space. e) The nucleus is surrounded by a diffuse cloud of electrons

a) The nucleus contains a tightly packed core of electrons

Which of the following represents the largest mass? a) 25 mg b) 25 ug c) 0.25 kg d) 2.5 g e) 250 ng

c) 0.25 kg

Which of the following compounds has an incorrect formula or is not named correctly? a) Chromic acid; H₂CrO₄ b) Dihydrogen monoxide; H₂O c) Aluminum hydroxide; Al₂O₃ d) Sodium fluoride; NaF e) Boron trichloride; BCl₃

c) Aluminum hydroxide; Al₂O₃

Which of the following is not a pure substance? a) oxygen gas b) dry ice (solid carbon dioxide) c) vodka d) gold metal e) water vapor

c) vodka

Which of the following nuclides has 70 neutrons, a mass number of 120 and 46 electrons? a) ¹⁹⁰Tl⁴⁺ b) ¹²⁰Bi²⁺ c) ¹²⁰Sn⁴⁺ d) ¹⁶⁴La³⁺ e) ¹²⁰Sb²⁺

c) ¹²⁰Sn⁴⁺