CHM Exam 4 Review- Extra Credit

Which molecule listed below has a polar covalent bond? a) NaCl b) H2 c) H2O

H2O

Which one of the following molecules is NOT capable of having resonance structures?

H2O

Which compound will dissolve in NH3? a) CO2 b) O2 c) H2S

H2S

Consider the following electronegativity values: H = 2.1 , Cl = 3.0 , F = 4.0 Which molecule below would you expect to have the more polar bond? a) HCl b) F2 c) H2 d) Cl2 e) HF

HF

The electronegativity value for Mg is 1.2 and the value for O is 3.5. Based on these values, what type of bond is expected for a compound formed between Mg and O?

Ionic

The elements with the highest electronegativity values tend to be found in the:

Upper-right side of the periodic table

Boyle's Law is expressed as:

V is proportional to 1/P

Charles's Law is expressed as:

V is proportional to T

Avogadro's Law is expressed as:

V is proportional to n

To solve problems using Avogadro's Law, which mathematical equation should be used?

V1/ n1= V2/ n2

To solve problems using Charles's Law, which mathematical equation should be used?

V1/T1= V2/T2

A balloon originally had a volume of 0.439 L at 44°C and a pressure of 729 torr. To what temperature must the balloon be cooled to reduce its volume to 378 mL if the pressure remained constant?

V1/T1= V2/T24 1) 439 mL/ 317 C= 378 mL/ T2 2) T2= 378 X (317/439) = 273 K 3) 273 K - 273 C= 0C

How many moles of gas were added to a balloon that started with 2.3 moles of gas and a volume of 1.4 L given that the final volume was 7.2 L?

V1/n1 = V2/n2 1) 1.4 L/ 2.3 mol = 7.2 L/ n2 * Cross multiply 2) 1.4 n2 = 16.56 3) 16.56/1.4= 11.8 4) 11.8 - 2.3= 9.5

Which one of the following is impossible for an ideal gas?

V1T1 = V2T2

Which substance listed below is a polar molecule? a) SiCl4 b) Cl2O c) NH4+ d) all of the above

b) Cl2O

What is the molecular geometry if you have a double bond, a single bond and 1 lone pair around the central atom?

bent

What is the molecular geometry of SCl2?

bent

What is the molecular geometry of ozone, O3?

bent

Which compound listed below will dissolve in water? a) CCl4 b) SiO2 c) NH3

c) NH3

Which molecule listed below is a nonpolar molecule? a) CO2 b) CCl4 c) BH3 d) all of the above

d) all of the above

Suppose a chemical reaction generated a 50% nitrogen/50% oxygen (by volume) mixture of gas that had a total volume of 22.4 liters at STP. This gas sample is composed of:

0.5 mole of N and 0.5 mol of O

If each of the following gas samples have the same temperature and pressure, which sample has the greatest volume?

1 gram of H2

1 torr is equal to...

1 mm Hg

How many liters of O2 (g) are needed to react completely with 56.0 L of CH4 (g) at STP to produce CO2 (g) and H2O (g)? Given: CH4 (g) + 2O2 (g) → CO2 (g) + H2O (g)

1 mol @ STP= 22.4 L 1) CH4= 22.4 O2= 44.8 H2O= 44.8 2) 56.1 L (44.8 L O2/22.4 L CH4 * 112.02 L O2

A gas sample occupies 3.50 liters of volume at 20.°C. What volume will this gas occupy at 100°C (reported to three significant figures)?

1) 3.50 L X (100+273)/ (20+ 273)= 4.46 L

What is the final volume of a balloon that was initially 500.0 mL at 25°C and was then heated to 50°C?

1) 500 X (50 + 273) / (25+273) = 542 mL

A 250 gram sample of water at the boiling point had 72.0 kJ of heat added. How many grams of water were vaporized? Heat of vaporization for water is 40.6 kJ/mole.

1) 72 kJ/ 40.6 kJ= 1.77 2) 1.77 X (18.015 g H2O/ 1 mol) = 31.9

A gas cylinder contains only the gases radon, nitrogen, and helium. The radon has a pressure of 222 torr while the nitrogen has a pressure of 446 torr. If the total pressure inside the cylinder is 771 torr, what is the pressure that is due to the helium?

1) 771 torr - 446 torr - 222 tor= 103 torr

If a mixture of gases contained 78% nitrogen at a pressure of 984 torr and 22% carbon dioxide at 345 torr, what is the total pressure of the system?

1) 984 torr + 345 torr= 1329 mm Hg 2) 760 mm Hg= 1 atm 3) 1329 mm Hg/ 760 mm Hg/atm= 1.75 atm

What is the electron geometry if you have 3 electron groups around the center atom?

trigonal planar

What is the molecular geometry if you have 3 single bonds and 1 lone pair around the central atom

trigonal pyramidal

What is the molecular geometry of PH3?

trigonal pyramidal

The change of a substance from a liquid to a gaseous form is called...

vaporization

The measure of the resistance to the flow of a liquid is called...

viscosity

Which symbol represents resonance structures?

↔

Which term matches the definition: A separation of charge within a bond?

dipole moment

Which of the following is considered a single electron group? a) triple bond b) double bond c) lone pair of electrons d) single bond e) all of the above

e) all of the above

The electron geometry and the molecular geometry of water are, respectively:

electron= tetrahedral molecular= bent

The electron geometry and the molecular geometry of ammonia (NH3) are, respectively:

electron= tetrahedral molecular= trigonal pyramidal

Which term matches the definition: The ability of an element to attract electrons within a covalent bond?

electronegativity

Which state of matter has a low density and an indefinite volume?

gases

Which state of matter has a low density and is easily compressed?

gases

What is the electron geometry if you have 2 electron groups around the center atom?

linear

What is the molecular geometry of carbon dioxide, CO2?

linear

Which state of matter has a high density and an indefinite shape?

liquids

Which of the following diatomic elements would have a mass of 19.08 grams stored in a 3.82 L container at 3,632 mm Hg and 100°C? (R= 0.0821 L atm/ mol K)

nRT/PV 1) P= 3632/760 --> 4.78 T= 100 + 273= 373 2) (19.08 g X 0.0821 X 373 K)/ (4.78 X 3.82) 3) 584.3/ 18.2596= 31.99 * O2 has mass of 31.99

A 3.76 g sample of a noble gas is stored in a 2.00 L vessel at 874 torr and 25°C. What is the noble gas? (R= 0.0821 L atm/ mol K)

nRT/PV 1) P= 874 torr/ 760= 1.15 T= (273+25)= 298 2) (3.76 g)(0.0821)(298)/ (1.15)(2)= 39.99 * Mass of Ar= 39.99

What is the pressure of a 1.0 L flask containing 0.60 g of He at 25°C? (R= 0.0821 L atm/ mol K)

p= nRT/V 1) mol He= 0.60/ 4.0026= 0.150 2) T= 25 +273= 298 3) (.150 X 0.0821 X 298)/ 1.0)= 3.7 atm

Which state of matter has a high density and a definite volume?

solid and liquid

All of the following statements are consistent with the kinetic molecular theory of gases EXCEPT:

strong attractive forces hold the gas molecules together

The tendency of a liquid to minimize its surface area is called...

surface tension

What is the electron geometry if you have 4 electron groups around the center atom?

tetrahedral

What is the molecular geometry if you have 4 single bonds around the central atom?

tetrahedral

What is the molecular geometry of CCl4?

tetrahedral

What is the molecular geometry of NH4+?

tetrahedral

What is the molecular geometry of SiH4?

tetrahedral

When a molecule has four electron groups with none of them lone pairs, the molecular geometry will be:

tetrahedral

How many lone electron pairs does the SH (-1 charged) polyatomic anion have?

2

What is the equivalent pressure of 1520 torr in units of atm?

2 atm

What is the equivalent pressure of 760 torr in units of mm Hg?

760 mm Hg

What is the pressure of 760 mm Hg when expressed in units of torr?

760 torr

If the number of moles of a gas initially contained in a 2.10 L vessel is doubled, what is the final volume of the gas in liters? (Assume the pressure and temperature remain constant.)

4.20

A 5.00 liter balloon of gas at 25°C is cooled to 0°C. What is the new volume (liters) of the balloon?

4.58 L

Ammonia gas decomposes according to the equation: 2NH3(g) → N2(g) + 3H2(g) If 15.0 L of nitrogen is formed at STP, how many liters of hydrogen will be produced (also measured at STP)?

45

What is the final volume (L) of a 10.0 L system that has the pressure doubled?

5.00 L

Which of the following statements about Lewis structures is FALSE? 1) An ionic bond occurs when electrons are transferred. 2) A duet is a stable electron configuration for helium. 3) A covalent bond occurs when electrons are shared. 4) An octet is when an atom has 8 valence electrons. 5) All of the above statements are true.

5: All of the above are true

If the initial pressure of a system was 1.00 atm and the volume was halved and the kelvin temperature was tripled, what is the final pressure?

6 atm

What is the equivalent pressure of 0.905 atm in units of mm Hg?

688 mm Hg

Which of following statements are consistent with the Kinetic Molecular Theory?

- Gases assume the shape and volume of their container because they are in constant, straight-line motion - Gas particles collide with each other without losing energy - Gases have a low density because there is so much empty space between the particles - Gases are compressible bc the volume taken up by the gas is almost entirely open space

How many kJ of heat are needed to completely vaporize 43.2 g of H2O? The heat of vaporization for water at the boiling point is 40.6 kJ/mole.

1) H2O= 1.008 (2) +15.999= 18.015 2) 43.2 g H2O / 18.015 X 40.6 = 97.4

Divers often inflate heavy duty balloons attached to salvage items on the sea floor. If a balloon is filled to a volume of 3.00 L at a pressure of 2.50 atm, what is the volume of the balloon when it reaches the surface?

1) P1V1= P2V2 2) (2.50) X (3.00) = (1) X (V2) 3) (2.50) X (3.00)/ (1)= V2 4) 7.50 L= V2

What is the final pressure of a system (atm) that has the volume increased from 0.75 L to 1.1L with an initial pressure of 1.25 atm?

1) P1V1=P2V2 2) (1.25 atm)(0.75 L)= P2 (1.1 L ) 3) (1.25)(.75)/(1.1)= P2 4) P2=0.85 atm

The initial volume of a gas cylinder is 750.0 mL. If the pressure of a gas inside the cylinder changes from 840.0 mm Hg to 360.0 mm Hg, what is the final volume the gas occupies?

1) P1V1=P2V2 2) P1= 840 V1= 750 P2= 360 V2= ? 3) (840) X (750) = (360) X (V2) 4) (840) X (750)/ (360) = V2 5) 1750 L = V2 6) 1750 L/1000 = 1.750 mL

A 325 mL sample of gas is initially at a pressure of 721 torr and a temperature of 32°C. If this gas is compressed to a volume of 286 mL and the pressure increases to 901 torr, what will be the new temperature of the gas (reported to three significant figures in °C)?

1) P2= (T2 X P1 X V1) / (V2 X T1) 2) P2= 331K X 1.033 atm X 2 L / 3.24 L X 310 K * 0.681 atm

If the volume of a gas container at 32.0°C changes from 1.55 L to 755 mL, what will the final temperature be?

1) T2= T1 X (V2/V1) 2) T2= (32 + 273) X (.755 L)/ 1.55 L) = 149 3) 149 - 273= -124 C

What is the initial temperature of a gas if the volume changed from 1.00 L to 1.10 L and the final temperature was determined to be 255.0°C?

1) V2/ (255+273) = V2 (273+T2) 2) 1.1/ 528 = 1/(273+T2) 3) 528 = 300.3 +T2 4) T2= 207 C

What is the final volume of a 500.0 mL gas container that increased in temperature from 299 K to 333 K while the pressure increased from 1.00 atm to 1.54 atm?

1) V2= P1V1T2/ T1P2 2) V2 = (1)(.500)(333)/ (299)(1.54)= 0.362 L

A balloon filled with 0.500 L of air at sea level is submerged in the water to a depth that produces a pressure of 3.25 atm. What is the volume of the balloon at this depth?

1) V2= V1 X P2/P1 2) V2= 0.500 X 1/3.25 3) V2= 0.154 L

At STP, 12.69 g of a noble gas occupies 14.09 L. What is the identity of the noble gas? (R= 0.0821 L atm/ mol K)

12.69 g / 14.09 L = X/ 22.4 L = 20.18 * Mass of Ne is 20.18

What is the angle between electron groups in the trigonal planar electron geometry?

120

What is the molecular weight of a gas if a 12.0 g sample has a pressure of 836 mm Hg at 25.0°C in a 2.00 L flask? (R= 0.0821 L atm/ mol K)

1) n= PV/RT 2) T= (273 + 25) = 298 K 3) P= 836/760= 1.1 4) 1.1 atmX 2.00 L/ .0821 L atm X 298 K= 0.0899 5) 12.0 g/ 0.0899= 133 amu

Water can be formed according to the equation: 2H2 (g) + O2 (g) → 2H2O (g) If 8.0 L of hydrogen is reacted at STP, exactly how many liters of oxygen at STP would be needed to allow complete reaction?

1. H2= 44.8 L O2= 22.4 L H2O= 44.8 L 2. 8.0 L H2 (22.4 L O2/ 44.8 L) = 4 L

What is the equivalent pressure of 968 mm Hg in units of atm?

1.27 atm

What is the angle between electron groups in the tetrahedral geometry?

109.5

Which molecule listed below is a polar molecule? a) H2O b) HCN c) NH3

All of the above

Which compound below is a polar molecule AND has a linear molecular geometry? a. H2O b. CO c. CH4 d. CO2

CO

When must temperature values in gas law calculations be expressed in kelvin units?

Charles, Ideal Gas, and Combined Gas Laws

Which of the following compounds would have a linear molecular geometry? 1. N2 2. H2S 3. CO2

N2 and CO2

Which of the following compounds have resonance structures?

O3

For an ideal gas, which of the following pairs of variables are inversely proportional to each other (if all other factors remain constant)?

P and V

What is the proper form of the combined gas law?

P1 X V1/T1= P2 X V2/T2

To solve problems using Boyle's Law, which mathematical equation should be used?

P1V1= P2V2

Which of the following has a tetrahedral electron geometry and a trigonal pyramidal molecular geometry?

PF3

The ideal gas law is:

PV= nRT

1 atm is equal to...

Pa= 101,325 mm Hg= 760 psi= 14.7 torr= 760

A certain volume of gas was confined in a rigid container. If the pressure of the gas sample in the container was doubled, what happened to the temperature?

The Kelvin temp doubled

Which of the following is NOT part of the Kinetic Molecular Theory?

The average energy of the particles is dependent on the molecular mass of the particle

Suppose you had a balloon containing 1 mole of helium at STP and a balloon containing 1 mole of oxygen at STP. Which statement(s) is(are) TRUE?

The balloons will have the same volume

Gas density can be calculated by dividing the mass of gas by its volume. If you took a balloon of gas and then warmed the balloon in a sunny window, what can now be said about the density of the gas in the balloon? Gas density can be calculated by dividing the mass of gas by its volume. If you took a balloon of gas and then warmed the balloon in a sunny window, what can now be said about the density of the gas in the balloon?

The gas density will decrease

Which molecule listed below has a nonpolar covalent bond? a) H2 b) H2O c) NaCl d) all of the above

a) H2