Chemistry Test 4 MC questions/answers

What are the key assumptions that distinguish an ideal gas from a real gas? (Select all that apply.)

- particles in an ideal gas have a mass, but no volume , there are neither attractive nor repulsive forces present between the particles in an ideal gas

The relationship between the number of particles of an ideal gas and volume is summarized by _______ , which states that the volume and the number of gas particles are directly proportional if the temperature and pressure are constant.

Avogadro's Law

Increased temperature means increased motion of the particles of a gas. If the particles are moving faster in the container, they will ______ with the walls more often and with _____ per collision. This leads to a greater overall force pushing on the walls and to a greater force per unit area or pressure

Collide, Greater Force

Although gas temperatures are often measured with thermometers that report temperatures in ____. Scientists generally use ______ temperatures for calculations

Degrees Celsius, Kelvin

Picture a gas in the apparatus shown below. If the temperature and the number of gas particles remain constant, how would you change the volume to DECREASE the pressure of the gas?

Increased volume leads to decreased pressure when temperature and number of gas particles are constant: move the piston up

The accepted SI unit for gas pressure is the

Pascal, Pa

If the following reaction is run in a cylinder with a movable piston that allows the pressure of gas in the cylinder to remain constant, and if the temperature is constant, what will happen to the volume of gas as the reaction proceeds? Why? N2(g) + 3 H2(g) → 2 NH3(g)

The volume of the reaction will decrease with time since there are fewer moles of products than there are moles of reactants.

Assuming ideal gas character, the partial pressure of any gas in a mixture is the pressure that the gas would exert if it were _________ in the container.

alone

When moles of gas and temperature are held constant, a decreased volume occupied by a gas leads to __________ gas pressure.

an increased

There are no _____ forces at all between the particles of an ideal gas.

attractive or repulsive

The coefficients in a(n) __________ provide us with information that we can use to build conversion factors that convert from an amount of one substance in a given chemical reaction to the corresponding amount of another substance participating in the same reaction.

balanced chemical equation

Chlorine gas is used in the production of

bottom of pg 17

The particles in a gas are constantly colliding with the walls of the container and with each other. Because of these collisions, the gas particles are constantly changing their _________ and their __________.

direction of motion, velocity

When the volume of a chamber that contains a gas decreases but the number of gas particles remains constant, there is an increase in the concentration (number of gas particles per liter) of the gas. This leads to an increase in the number of particles near any given area of the container walls at any time and to an increase in the number of collisions against the walls per unit area in a given time. More collisions mean an increase in the ___________, or pressure, of the gas.

force per unit area

As the temperature of a gas increases, the particles' velocity

increases

Conversion factors constructed from molarities can be used in stoichiometric calculations in very much the same way conversion factors from ________ are used. When a substance is pure, its molar mass can be used to convert back and forth between the measurable property of ______ and moles. When a substance is in solution, its molarity can be used to convert between the measurable property of __________ and moles of solute.

molar mass, mass, volume of solution

The observation that the pressure of an ideal gas is inversely proportional to the volume it occupies if the __________ and the temperature are constant is a statement of Boyle's Law.

mole of gas

Picture a gas in the apparatus shown below. If the temperature and the number of gas particles remain constant, how would you change the volume to INCREASE the pressure of the gas?

move the piston down

Hydrogen gas is used for many purposes, including the hydrogenation of vegetable oils to make margarine. The most common industrial process for producing hydrogen is "steam reforming," in which methane gas, CH4, from natural gas reacts with water vapor to form carbon monoxide gas and hydrogen gas.

pg 1

Most of the sodium chlorate, NaClO3, produced in the United States is converted into chlorine dioxide, which is then used for bleaching wood pulp. NaClO3(aq) + 2 HCl(aq) → ClO2(g) + ½ Cl2(g) + NaCl(aq) + H2O(l)

pg 10

Consider the precipitation reaction that takes place when a water solution of aluminum nitrate, Al(NO3)3, is added to a water solution of potassium phosphate, K3PO4.

pg 11

Consider the neutralization reaction that takes place when nitric acid reacts with aqueous potassium hydroxide.

pg 12

Consider the neutralization reaction that takes place when sulfuric acid reacts with aqueous sodium hydroxide.

pg 13

Iodine pentafluoride is an incendiary agent, a substance that ignites combustible materials. This compound is usually made by passing fluorine gas over solid iodine, but it also forms when iodine monofluoride changes into the element iodine and iodine pentafluoride.

pg 14

What is the molarity of a solution made by dissolving 130.939 g of SnBr2 in water and diluting with water to 1.25 L total?

pg 15

Ethylene oxide

pg 16

The bond between nitrogen atoms in N2 molecules is very strong, making N2 very unreactive. Because of this, magnesium is one of the few metals that react with nitrogen gas directly. This reaction yields solid magnesium nitride.

pg 2

The thiocyanate polyatomic ion, SCN −, is commonly called a pseudohalogen because it acts very much like halide ions. For example, we know that the pure halogens consist of diatomic molecules, such as Cl2. Thiocyanate ions form similar molecules in the following reaction:

pg 3

Potassium perchlorate, KClO4, is a better oxidizing agent than the potassium chlorate, KClO3, described in the previous problem. Potassium perchlorate, which is used in explosives, fireworks, flares, and solid rocket propellants, is made by carefully heating potassium chlorate to between 400°C and 500°C. The unbalanced equation for this reaction is KClO3 → KClO4 + KCl

pg 4

Tetraboron carbide, B4C, is a very hard substance used for grinding purposes, ceramics, and armor plating. Because boron is an efficient absorber of neutrons, B4C is also used as a protective material in nuclear reactors. The reaction that forms B4C from boron(III) oxide, B2O3, is 2 B2O3 + 7 C → B4C + 6 CO (at 2400°C)

pg 5

Chromium(III) oxide, often called chromic oxide, has been used as a green paint pigment, as a catalyst in organic synthesis, as a polishing powder, and to make metallic chromium. One way to make chromium(III) oxide is by reacting sodium dichromate, Na2Cr2O7, with ammonium chloride at 800 to 1000°C to form chromium(III) oxide, sodium chloride, nitrogen, and water.

pg 6 and 7

What is the molarity of a solution made by dissolving 34.277 g of aluminum sulfate, Al2(SO4)3, in water and diluting with water to 500.0 mL total?

pg 8

What is the molarity of a solution made by dissolving 15.710 g of potassium carbonate, K2CO3, in water and diluting with water to 110.0 mL total?

pg 9

The ideal gas model is used to predict changes in four related gas properties:

1) volume 2) number of particles 3) temperature 4) pressure

Oxygen, O2, molecules at normal temperatures and pressures move an average of _______ between collisions.

100 nm

The theoretical yield is the maximum amount of product that could be formed from the given amounts of reactants. This is the amount of product that could be obtained if ______ of the limiting reactant were converted to product and if this product could be isolated from the other components in the product mixture without any ______. The efficiency of a reaction can be evaluated by calculating the percent yield, the ratio of the _______ yield to the theoretical yield expressed as a percentage.

100%, loss, actual

There are _______ mmHg per atm.

760

_____ gases deviate somewhat from predicted behavior of an ideal gasses

Real

STP stands for "standard temperature and pressure".

Standard temperature is -273.15 K -0 degrees Celsius and Standard pressure is -1 atm, 101.325 kPa, or 760 mmHg

If a calculation calls for you to convert from an amount of one substance in a given chemical reaction to the corresponding amount of another substance participating in the same reaction, it is an equation __________ problem.

stoichiometry

Dalton's law of partial pressures states that the total pressure of a mixture of gases is equal to the __________ of the partial pressures of gas all the gases.

sum

The tip-off for limiting reactant problems is that you are given _________ of reactants in a chemical reaction, and you are asked to calculate the maximum _________ that they can form.

two or more amounts, amount of product

When two solutions are mixed to start a reaction, it is more convenient to measure their ________ than their masses.

volumes