Third Quarter Exam Review

The value of DH° for the reaction below is -790 kJ. The enthalpy change accompanying the reaction of 0.95 g of S is __________ kJ. 2S (s) + 3O2 (g) -> 2SO3 (g)

-11.7 kJ

Using the equation 2Na2O2 (s) + 2H2O (l) -> 4NaOH (s) + O2 (g), the value of DH° for the reaction below is -126 kJ. The amount of heat that is released by the reaction of 25.0 g of Na2O2 with water is

-20.2 kJ

In the reaction Ca + Cl2 -> CaCl2, what is the mole ratio of chlorine to calcium chloride?

1 chlorine to 1 calcium chloride

In the reaction 2C + O2(g) -> 2CO(g), what is the volume ratio of O2 to CO?

1 mole oxygen to 2 moles carbon monoxide

In the reaction N2 + 3H2 -> 2NH3, what is the mole ratio of nitrogen to ammonia?

1 nitrogen to 2 ammonia

In the reaction Zn + H2SO4 -> ZnSO4 + H2, what is the mole ratio of zinc to sulfuric acid?

1 zinc to 1 sulfuric acid

In the reaction 2H2(g) + O2(g) -> 2H2O(g), what is the volume ratio of H2 to H2O?

2 moles of hydrogen to 2 moles water

In the equation H2(g) + Cl2(g) -> 2HCl(g), one volume of hydrogen yields how many volumes of hydrogen chloride?

2 volumes of hydrogen chloride

When hydrogen burns, water vapor is produced. The equation is 2H2(g) + O2(g) -> 2H2O(g). If 12 L of oxygen are consumed, what volume of water vapor is produced?

24 liters of water

The Haber process for producing ammonia commercially is represented by the equation N2(g) + 3H2(g) -> 2NH3(g). To completely convert 9.0 mol hydrogen gas to ammonia gas, how many moles of nitrogen gas are required?

3 moles of nitrogen gas

For the reaction SO3 + H2O -> H2SO4, how many grams of sulfur trioxide are required to produce 4.00 mol of sulfuric acid?

320.24 grams sulfur trioxide

In the equation 2KClO3 -> 2KCl + 3O2, how many moles of oxygen are produced when 3.0 mol of KClO3 decompose completely?

4.5 moles oxygen

The equation for the production of methane is C + 2H2(g) -> CH4(g). How many liters of hydrogen are needed to produce 20 L of methane?

40 liters of hydrogen

For the reaction AgNO3 + NaCl -> NaNO3 + AgCl, how many moles of silver chloride, AgCl, are produced from 7 mol of silver nitrate AgNO3?

7 moles silver chloride

endothermic reaction

A reaction that ABSORBS energy in the form of heat; positive delta H

spontaneous reaction

A reaction that will proceed without any outside energy; negative delta G

The expression V = kn is a statement of

Avogadro's Law or principle

The ideal gas law combines

Boyle's law, Charles's law, Gay-Lussac's law and Avogadro's law

Formula to calculate enthalpy

H products - H reactants

Which of the following has a melting point greater than room temperature?

Iron

suspention

Is a heterogeneous mixture containing a liquid in which visible particles settle

Why is vapor-pressure lowering a colligative property?

It depends on the concentration of the solute and not on the solute's identity.

Which reactant controls the amount of product formed in a chemical reaction?

Limiting reactant controls the amount of product

Symbol that represents molarity

M

formula for molar mass of a gas

M = mRT/PV

Symbol used to represent pressure

P

formula for Gay-Lussac's law

P1/T1=P2/T2

formula for Boyle's law

P1V1 = P2V2

formula for combined gas law

P1V1/T1=P2V2/T2

formula for ideal gas law

PV=nRT

formula for Charles's law

V1/T1=V2/T2

formula for Avogadro's law

V1/n1=V2/n2

Formula for mole fraction

Xa=na/na+nb Xb=nb/na+nb

exothermic reaction

a chemical reaction in which heat is released to the surroundings; negative delta H

A solid with a low melting point is most likely

a covalent compound

nonspontaneous reaction

a reaction that does not favor the formation of products at the specified conditions; positive delta G

Compared with a 0.01 m sugar solution, a 0.01 m MgCl2 solution has

about three times the freezing point depression since its I=3 while sugar has an I=1.

Compared with a 0.01 m sugar solution, a 0.01 m KCl solution has

about twice the freezing point depression since its I = 2 while sugar has an I=1.

The solubility of a substance at a given temperature can be expressed as

amount of solute per amount of solvent

Compared with the freezing-point depression for a solution of an electrolyte that dissociates into a 3+ and a 3- ion, the freezing-point depression for an equally concentrated solution of an electrolyte that dissociates into a 1+ and a 1- ion is likely to

be the same since there are the same number of ions per mole of solute.

Gay-Lussac recognized that at constant temperature and pressure, the volumes of gaseous reactants and products

can be expressed as ratios of small whole numbers

Which mixture contains particles that are in a dispersed phase and do not settle out?

colloid

Symbol used to represent free energy

delta G

Symbol used to represent enthalpy

delta H

Symbol used to represent entropy

delta S

Symbol used to represent change in temperature

delta T

What is the process by which molecules of a gas randomly encounter and pass through a small opening in a container?

effusion

Which of the following is true in an exothermic reaction?

energy of products < energy of reactants < activation energy

A chemical reaction involving substances A and B stops when B is completely used. B is the

limiting reactant

Water in air is an example of which solute-solvent combination?

liquid-gas

In the chemical equation wA + xB -> yC + zD, if one knows the mass of A and the molar masses of A, B, C, and D, one can determine

mass of any of the reactants or products

Equation for converting mass to moles

mass/molar mass

The process by which a solid becomes a liquid is

melting

Which terms express concentration?

molality, molarity, percent by mass or volume and mole fraction

Knowing the mass and volume of a gas at STP allows one to calculate the

molar mass of the gas

According to Graham's law, two gases at the same temperature and pressure will have different rates of diffusion because they have different

molar masses

If one knows the mass and molar mass of reactant A and the molar mass of product D in a chemical reaction, one can determine the mass of product D produced by using the

mole ratio of A to D from the chemical reaction

Equal volumes of diatomic gases under the same conditions of temperature and pressure contain the same number of

molecules

formula for calculating moles of wanted

moles given in problem x {#mole wanted/#moles given}

Formula for molality

moles of solute/kg of solvent

Formula for molarity

moles of solute/liters of solution

Symbol representing moles

n

organized reaction

negative delta S; changing from a gas to a liquid or a liquid to a solid

How many times greater is the rate of effusion of oxygen gas than that of carbon dioxide gas at the same temperature and pressure?

oxygen is 1.2 times faster

chaotic reaction

positive delta S; changing from a solid to a liquid, liquid to a gas, or solid to a solution

Which of the following will dissolve most rapidly?

powdered sugar in hot water

formula for heat

q=mcΔT

Graham's law formula

rate of effusion 1 / rate of effusion 2 = sqrt(molar mass 2/molar mass 1)

Which of the following is a thoroughly mixed homogeneous mixture of substances in a single phase?

solution

If the amount of dissolved solute in a solution at a given temperature is greater than the amount that can permanently remain in solution at that temperature, the solution is said to be

supersaturated

What determines the average kinetic energy of the molecules of any gas?

temperature

Colligative properties depend on

the concentration of the solute particles

Which of the following best describes heat?

the energy transferred between samples of matter because of a difference in their temperatures

When pressure, volume, and temperature are known, the ideal gas law can be used to calculate

the molar amount (number of moles)

For reactants or products that are gases, the coefficients in the chemical equation indicate

the molar volume

The solubility of a solute depends on

the nature of the solute and the temperature of the solvent

The ideal gas law is equivalent to Charles's law when

the number of moles and the pressure are constant

The ideal gas law is equivalent to Boyle's law when

the number of moles and the temperature are constant

Hess's law

the overall enthalpy change in a reaction is equal to the sum of enthalpy changes for the individual steps in the process

The ideal gas law is equivalent to Avogadro's law when

the pressure and the temperature are constant

According to Graham's law, the rates of diffusion of two gases at the same temperature and pressure are inversely proportional to

the square roots of their molar masses

The standard molar volume of a gas is all of the following except

the volume occupied by 1 mol of a gas at STP and equal for all gases under the same conditions and 22.4 L at STP

If gas A has a molar mass greater than that of gas B and samples of each gas at identical temperatures and pressures contain equal numbers of molecules, then

the volume of gases A and B are identical (equal).

How many phases does a carbonated beverage over ice contain? phases.

three phases

A heterogeneous mixture always contains

two or more substances that are visibly distinguishable

Gibb's free energy equation

ΔG = ΔH - TΔS