Practice Exam 2

Upon mixing a clear colorless BaCl2 solution with a clear, colorless Na2SO4 solution according to the reaction below, a student observes a white cloudiness form. What is responsible for the cloudiness that is observed?BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2NaCl(aq)

BaSO4

What is the mass of 3.01 mol of sulfur atoms?

96.5 g

When the equation below is balanced with the lowest possible whole number coefficients, what is the sum of the coefficients? Ca(s) + HCl(g) → CaCl2(s) + H2(g)

5

Choose the best classification of the reaction represented by the following equation: 2KClO3(s) → 2KCl(s) + 3O2(g)

decomposition

Choose the best classification of the reaction represented by the following equation: Pb(NO3)2(aq) + CaCl2(aq) → PbCl2(s) + Ca(NO3)2(aq)

precipitation

The average mass of one atom of copper is 63.55 amu. What is the mass of Avogadro's number of copper atoms?

63.55 g

The chemical equation below is not balanced. What is the coefficient of iron when the equation is balanced with smallest whole number coefficients?Fe(s) + O2(g) → Fe2O3(s)

4

Which of the choices is the correctly balanced form of the following equation?C6H14(l) + O2(g) → CO2(g) + H2O(l)

2C6H14(l) + 19O2(g) → 12CO2(g) + 14H2O(l)

How is the reaction shown below best classified? 2HgO(s) → 2Hg(l) + O2(g)

decomposition

Aspirin is the common name for acetyl salicylic acid, C9H8O4. One tablet contains 0.325 g of aspirin. How many moles of aspirin is this?

1.80 × 10-3 mol

Choose the best classification of the reaction represented by the following equation: HBr(aq) + KOH(aq) → KBr(aq) + H2O(l)

acid-base

Methanol (CH3OH) is the fuel used by racecars in the Indianapolis 500. It burns in the engine according to the equation below. How many moles of oxygen gas are necessary to react completely with 425 moles of methanol?2CH3OH(l) + 3O2(g) → 2CO2(g) + 4H2O(g)

638 mol

How is the reaction shown below best classified?

2NaCl(s) + F2(g) → 2NaF(s) + Cl2(g)

single-replacement

A sample of aluminum contains 2.91 × 1022 atoms of aluminum. What is the mass of this sample? [Molar mass: Al, 26.98 g/mol]

1.30 g

What mass of sodium hydroxide is necessary to react with a solution containing 73.00 g HCl, according to the chemical equation below? [Molar masses: NaOH, 39.99 g/mol; HCl, 36.45 g/mol]

NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)

80.09 g

A sample of sulfur contains 1.81 × 1024 atoms of sulfur. How many moles of sulfur does this represent?

3.01 mol

How many molecules of water are present in a 5.65 mole sample of water?

3.40 × 1024 molecules

What mass of helium is contained in a 2.0 L balloon at 30.0oC and 735 mm Hg?

0.312 g

What state(s) of matter is most compressible?

gas

Which statement is true concerning an ideal gas?

Gases behave more ideally at low pressure than at high pressure.

Who formulated the relationship between the volume and the pressure of a gas?

Boyle

A barometer measures

atmospheric pressure

Which of the following statements correctly describes Avogadro's Law?

Equal volumes of any ideal gas contain the same number of moles, if measured at the same temperature and pressure.

Correct

Which statement INCORRECTLY describes what happens to a sample of gas when it experiences an increase in temperature?

The number of gas particles increases.

Which of the following represent STP (Standard Temperature and Pressure) conditions?

T = 273 K and P = 1 atm

A balloon filled with helium has a volume of 1.00 × 103 L at 20°C. What would be the balloon's volume at 30°C, if the pressure surrounding the balloon remains constant?

1.03 × 103 L

Glycerol is a very polar compound. Dimethyl ether is only slightly polar. Which statement is TRUE?

Glycerol will have a greater surface tension than dimethyl ether.

Which substance is expected to have the highest boiling point?

CH3OH

What process is responsible for the formation of dew on the grass early in the morning?

condensation

An aerosol spray paint can with a volume of 350 mL registers a pressure of 4.5 atm at room temperature. What can be said about the pressure inside the can if it is stored outside during the winter months?

The pressure of the gas will be less than 4.5 atm.

What quantity is directly proportional to the kinetic energy of the particles in a gas?

absolute temperature

Which of the following is TRUE for a liquid that is placed in a sealed container?

Once equilibrium is established between the liquid and the vapor, the rate of the evaporation process will equal the rate of condensation.

Which statement concerning the three states of matter is FALSE?

Particles of a liquid have a rigid, ordered arrangement due to the high speeds of the liquid particles.