ABeka Chemistry 2024 Test 3 EXAM

An engineer needs to know the amount of H2O that can be produced from 2.6 mol C3H8 according to the balanced equation below. What mole ratio should he use? C3H8(g) + 5 O2(g) ---> 3 CO2(g) + 4 H2O(g)

(4 mol H2O) / (1 mol C3H8)

What is the pressure of a gas at STP?

100 kPa

A sample of gas occupies 1.55 L at STP. What will the pressure be if the temperature is raised to 298.15 K and the gas expands to 1.63 L?

104 kPa V2/ V1 = 1.63L / 1.55L T2/ T1 = 298.15 K / 273.15 K P2 = P1[(V1/V2)(T2/T1)] = 100 kPa [(1.55 L/1.63 L)(298.15 K / 273.15 K) = 103.7 kPa or 104 kPa

if 783,000,000 is converted to scientific notation, what should the power of 10 be?

10^8

How may significant digits are in 0.0230?

3

When an effervescent tablet is dropped into water, the resulting reaction produces gaseous carbon dioxide. Suppose someone drops an effervescent tablet into a container half-filled with water and then immediately seals the container. Will the pressure of the gas inside the container increase or decrease if the temperature is kept constant? Why?

Increase; P and n are directly related at constant T and V

Match each law with the correct equation. Dalton's law of partial pressures

P(Total) = p1 + p2 + p3 +...

Match each law with the correct equation. Boyle's law

P1V1 = P2V2

The weighted average of the atomic masses of the naturally occurring isotopes of an element is its ______.

average atomic mass

Which type of reaction has the form A + BC ---> AB + C?

single displacement

What is the nuclear symbol of a neutral atom with 18 neutrons and 8 protons?

^26/8 O

Phosphorus and chlorine react according to the following balanced equation: P4(s) + 10 Cl2(g) ---> 4 PCI5(s) If 5.00 g of P4 and 3.00 L of CI2 at 298 K and 103.0 kPa react completely, how many moles of PCI5 will be produced? M(base P base4) = 123.90 g/mol

0.0499 mol (5.00 g P4)[(1 mol P4) / 123.90 g][(4 mol PCI5) / 1 mol P4] = 0.1614 mol PCI5 PV = nRT n = PV/ RT [(103.0 kPa)(3.00 L) / (8.314 LkPa/kmol)(298 K)] = 0.1247 mol CI2 (0.1247 mol CI2) [(4 mol PCI5) / (10 mol CI2)] = 0.04988 mol or 0.0499 mol PCI5 CI2 is the limiting reactant; 0.0499 mol PCI5 are produced

What should a length in yards be multiplied by to convert it to meters? (1yard = 0.9144m)

0.9144m/1 yd

What volume of H2 at STP will be produced if 2.73 mol Na react according to the following balanced equation? 2 Na(s) + 2 H2O(I) ---> H2(g) + 2 NaOH(aq)

31.0 L (2.73 mol Na) [(1 mol H2) / (2 mol Na)] = 1.365 mol H2 PV = nRT V = (nRT/P) = [(1.365 mol H2)(8.314 LkPa/Kmol)(273.15 K)] / 100 kPa = 30.99 L or 31.0 L

What is the molar mass of sucrose, C12H22O11?

342.30 g/mol M (Base C12H22O11) = 12M(Base C) + 22M(base H) + 11M(base O) = 12(12.011 g/mol) + 22(0.0080 g/mol) + 11(15.999 g/mol) = 144.132 g/mol + 22.1760 g/mol + 175.989 g/mol = 342.297 g/mol or 342.30 g/mol

When the following equation is balanced, what is the correct coefficient of AI? ? AI2O3(s) ---> ___?___ AI(I) + ? O2(g)

4 2 AI2O3(s) ---> ? AI(I) + 3 O2(g) (2 X 3 O = 3 X 2 O) 2 AI2O3(s) ---> 4 AI(I) + 3O2(g) (2 X 2 AI = 4 X 1 AI)

What is the value of R?

8.314 L X kPa/(K X mol)

What is the pressure of a sample of gas connected to an open-end manometer if the atmospheric pressure is 103.4 kPa and the mercury level is 46.0 mm lower on the atmospheric side?

97.3 kPa (46.0 mmHg) [(1 torr)/ (1mmHg)] [(101.325kPa)/ (760 torr)] = 6.132 kPa P(gas) < P(atm) P(gas) = 103.4 kPa - 6.132 kPa = 97.268 kPa or 97.3 kPa

What is the pressure of a sample of gas collected over water at 25*C if the atmospheric pressure is 102.4 kPa and the vapor pressure of water at this temperature is 3.17 kPa?

99.2 kPa P(gas) = P(total) - P(H2O) 102.4 kPa - 3.17 kPa = 99.23 kPa or 99.2 kPa

Some elements undergo alpha decay, in which an atom of the element releases a particle from the nucleus consisting of 2 protons and 2 neutrons. What remains after alpha decay? How do you know?

A different element; it has a different number of protons

A rudimentary device to measure pressure consists of a stretchy material, such as a rubber sheet, sealed tautly over the mouth of a jar. A straw is taped horizontally from the center of the material past the edge of the jar. As the Atmospheric pressure changes, the material either caves in or bulges outward, causing the straw to rise and fall in a measurable way. Which laboratory instrument is the most similar to and why?

Aneroid barometer; pressure is measured by volume changes of a sealed container

What is the correct empirical formula for calcium phosphate?

Ca3(PO4)2

What is the chemical symbol for copper?

Cu

Alice is standing 2 m from a sealed container containing two gases, A and B. Gas B has twice the molar mass of gas A. The container is opened, allowing the gases to diffuse. Which gas will reach Johnny first?

Gas A arrives first

Owen was asked to identify the limiting reactant if 5 mol N2H4 and 3 mol N2O4 react according to the following unbalanced equation: _____ N2H4(I) + _____N2O4(I) ---> _____N2(g) + _____ H2O(I) He setup his first calculations as follows: (5 mol N2H4) [(4 mol N2)/ (2 mol N2H4)] What is his error?

He used the incorrect coefficients in his mole ratio

Daisy is planning an experiment to compare how quickly different brands of chocolate coated ice-cream bars melted. She has one experimental group for each different brand. What should Daisy's control group be and why?

No control group; a control group is not needed because two or more experimental groups are being compared.

Which assumption of the kinetic theory of matter best explains why the volume of a gas is affected by temperature?

The kinetic energy of gas molecules is directly related to temperature

Match each law with the correct equation. Charles's law

V1/T1 = V2/T2

Match each law with the correct equation. Avogadro's law

V1/n1 = V2/n2

How close a measurement is to its actual, exact value is its ______.

accuracy

Which separation technique is based on the different way that each component in a mixture interacts with a stationary liquid or solid phase?

chromatography

What is the name of the ionic compound Cu2O?

copper (I) oxide

Which type of reaction occurs when a single reactant breaks down into two or more simpler substances?

decomposition

What is the name for the process of mixing molecules of one substance through another substance by random molecular motion?

diffusion

What is the name of the molecular compound P2S3?

diphosphorus trisulfide

The absorbance A of a solution is related to its concentration c by the equation A/c + Eb, where the product Eb is constant. Are absorbance and concentration directly or inversely proportional? What pattern does this equation follow?

directly proportional; x = ky

To convert from the mass of a substance in grams to the amount of a substance in moles, ______ by the molar mass of the substance.

divide

Which experiment led to the development of the planetary model?

gold foil experiment

A mixture of pure substances that are incompletely mixed and form distinct phases is a ______ mixture.

heterogeneous

What term refers to a gas that exactly obeys the assumptions of the kinetic theory?

ideal gas

Which state of matter is difficult to compress and has particles that are close together but free to move?

liquid

If the percent composition of a compound is known, what one additional piece of information is needed to determine the compound's molecular formula?

molar mass

The formula that tells how many of each type of atom is found in an actual molecule of a substance is its ______ formula.

molecular

In nitrogen dioxide and dinitrogen pentaoxide, the masses of oxygen that combine with 15 g of nitrogen are in a ratio of approximately 4 to 5. This fact demonstrates the law of ______.

multiple portions

What is the SI unit of pressure?

pascal

Density is an example of a _______ property.

physical

In the engineering design process, what is a model of a design that is used for testing called?

prototype

Match each law with the correct equation. Graham's law of diffusion

rate1/rate2 = Square root of (M2/M1)