chemistry questions powerpoint

2010-1A12

a. What is the name given to a compound containing a COOH

functional group?

b. Name the following compound: CH3COOH

2010-1A12

a. What is the name given to a compound containing a COOH functional group?

b. Name the following compound: CH3COOH

Answer: a. Carboxylic Acidb. Acetic Acid or Ethanoic Acid

2010-1A13

If a negatively charged rod is held near an uncharged metal ball, the metal ball

a. becomes negatively chargedb. becomes positively charged

c. becomes polard. is unaffected

e. affect cannot be determined

2010-1A13

If a negatively charged rod is held near an uncharged metal ball, the metal ball

a. becomes negatively chargedb. becomes positively charged

c. becomes polard. is unaffected

e. affect cannot be determined

Answer: C

2010-1A15

Which of the following mixtures would create a buffer?a. HCl and NaCl

b. HNO3 and NaNO3

c. H3PO4 and NaH2PO4

d. H2SO4 and CH3COOH

e. NH3 and NaOH

2010-1A15Which of the following mixtures would create a buffer?

a. HCl and NaCl

b. HNO3 and NaNO3

c. H3PO4 and NaH2PO4

d. H2SO4 and CH3COOH

e. NH3 and NaOH

Answer: C

Gives a mixture of a weak acid (H3PO4) and its conjugate weak base (H2PO4

-).

2010-1A16

How many electrons per minute traverse any cross-section of a wire which carries a current of 2 amperes?

The charge of an electron is 1.6 X 10-19 coulomb.

Answer: 7.5 x 1020 electrons/minute

i = q / t 2 amp = (2 coul/sec)(1 elect/1.6x10-19coul)(60 sec/min)

2010-1A16

How many electrons per minute traverse any cross-section of a wire which carries a current of 2

amperes? The charge of an electron is 1.6 X 10-19 coulomb.

Answer: 7.5 x 1020 electrons/minutei = q / t

2 amp = (2 coul/sec)(1 elect/1.6x10-

19coul)(60 sec/min)

2010-1A18

Which species is the reducing agent in the following balanced reaction?

Mn2+(aq) + S2O82-(aq) + 2H2O(l) MnO2(s)

+ 4H+(aq) + 2SO42-(aq)

2010-1A18

Which species is the reducing agent in the following balanced reaction?Mn2+(aq) + S2O8

2-(aq) + 2H2O(l) MnO2(s) + 4H+(aq) + 2SO4

2-(aq)

Answer: Mn2+

Mn2+ gets oxidized to Mn4+ and in the process reduces S+7 to S+6

2010-1C15

Which of the following compounds have the ability to form hydrogen bonds? (there may be more than one)

a. H2O

b. BF3

c. NH3

d. HF e. CH4

2010-1C15

Which of the following compounds have the ability to form hydrogen bonds? (there may be more than one)

a. H2O

b. BF3

c. NH3

d. HF e. CH4

Answer: A, C, and D

2010-1C18

Calculate the molar mass of the amino acid, glycine, which has the following structure:

H2N C

H

H

C

O

OH

2010-1C18

Calculate the molar mass of the amino acid, glycine, which has the following structure:

Answer: 75 g/mol = 2 C + 5 H + 1 N + 2 O

= 2 (12 g/mol) + 5 (1 g/mol) + 1 (14 g/mol) + 2 (16 g/mol)

H2N C

H

H

C

O

OH

2010-2A12

What is the common name for acetylsalicylic acid?

2010-2A12

What is the common name for acetylsalicylic acid?

Answer: Aspirin

2010-2A14

During the metabolic process, what is the name of the molecules that carry energy

from the citric acid cycle (Kreb’s cycle) pathway to the electron transport

system?

2010-2A14

During the metabolic process, what is the name of the molecules that carry energy

from the citric acid cycle (Kreb’s cycle) pathway to the electron transport

system?

Answer: NADH or FADH or FADH2

2010-2A15

What is the name of the polyatomic anion MnO4

- ?

2010-2A15

What is the name of the polyatomic anion MnO4

- ?

Answer: Permanganate

2010-2A18

What element has 10 protons?

2010-2A18

What element has 10 protons?

Answer: Neon

2010-2C12

What is the ground state electron configuration for Sr (Atomic Number = 38)?

2010-2C12

What is the ground state electron configuration for Sr (Atomic Number = 38)?

Answer: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2

or 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 5s2

2010-2C15

Which element in the periodic table has the largest electronegativity?

2010-2C15

Which element in the periodic table has the largest electronegativity?

Answer: Fluorine or F

2010-2C17

The oxygen released during photosynthesis originates from what

compound?

2010-2C17

The oxygen released during photosynthesis originates from what

compound?

Answer: Water (H2O)

2010-2C18

What is the oxidation number of carbon in formaldehyde?

O

C

H H

2010-2C18

What is the oxidation number of carbon in formaldehyde?

O

C

H H

Answer: ZeroEach hydrogen is +1, for a total of +2. Oxygen is -2.The carbon must have an oxidation number of zero to have a neutral compound.

2010-3A13

What is the common name for elements in Group 2A (second column) in the

periodic table?

2010-3A13

What is the common name for elements in Group 2A (second column) in the

periodic table?

Answer: Alkaline Earth Metals

2010-3A14

Draw the Lewis structure for BF3. [Boron is in group 3A and fluorine is in

group 7A.]

F B

F

F F B

F

F

2010-3A14

Draw the Lewis structure for BF3. [Boron is in group 3A and fluorine is in

group 7A.]

F B

F

F F B

F

F

Must have the 3 fluorines positioned around the boron (left, right, top, or bottom) with single bonds. Each fluorine should have 3 lone pairs (or 6 lone pair electrons).

NOT ACCEPTABLE!!!!

2010-1B32

Calculate G for the combustion of propane in units of kJ.

C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(g)

2010-1B32

Calculate G for the combustion of propane in units of kJ.

C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(g)

Answer: -2073.1 kJ

DG° = [3 mol (-394.4 kJ/mol) + 4 mol (-228.6 kJ/mol)] – [1 mol (-24.5 kJ/mol) + 5 mol (0

kJ/mol)]

2010-1D32

A 0.2688 g sample of a triprotic weak acid (abbreviate H3A) is required to completely react

with 49.2 mL of a 0.08133 M KOH solution. Calculate the molar mass of the weak acid.

2010-1D32

A 0.2688 g sample of a triprotic weak acid (abbreviate H3A) is required to completely react

with 49.2 mL of a 0.08133 M KOH solution. Calculate the molar mass of the weak acid.

Answer: 201.5 g/mol

H3A + 3 OH- 3 H2O + A3-

AH mol10 x 1.33

KOH mol 3

AH mol 1

KOH L

KOH mol 0.08133

KOH mL 1000

KOH LKOH mL 49.2 3-3

3 xxx

Molar Mass = 0.2688 g / 1.33 x 10-3 molMolar Mass = 201.5 g/mol

2010-2B32

The concentration of a compound is 1.0 x 10-2 M. If the first order reaction rate constant (k) for the compound is 0.497 days-1, calculate

the concentration 2 days later, assuming first order kinetics.

2010-2B32

The concentration of a compound is 1.0 x 10-2 M. If the first order reaction rate constant (k)

for the compound is 0.497 days-1, calculate the concentration 2 days later, assuming first order

kinetics.

Answer: 3.7 x 10-3 M

2010-2D32

Calculate the molarity of concentrated HNO3 given the following:

molar mass = 63.01 g/mol, wt% = 70.4, and density = 1.41 g/mL.

2010-2D32

Calculate the molarity of concentrated HNO3 given the following:

molar mass = 63.01 g/mol, wt% = 70.4, and density = 1.41 g/mL.

Answer: 15.8 mol/L

L / mol 8.15HNO g 63.01

HNO mol

nsol' L

nsol' mL 1000

nsol' mL

nsol' g 1.41

nsol' g 100

HNO g 70.4

3

33 xxx

2010-3B32

25.0 g of C3H8 (g) is mixed with 25.0 g of O2 (g). If these compounds react

according to the balanced chemical equation given below, how many grams of

excess reactant remain after the reaction is complete?

[C3H8 = 44.1 g/mol; O2 = 32.0 g/mol; CO2 = 44.0 g/mol; H2O = 18.0 g/mol]

C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(g)

2010-3B32

25.0 g of C3H8 (g) is mixed with 25.0 g of O2 (g). If these compounds react

according to the balanced chemical equation given below, how many grams of

excess reactant remain after the reaction is complete? [C3H8 = 44.1 g/mol; O2 = 32.0 g/mol; CO2 = 44.0 g/mol; H2O = 18.0

g/mol]

C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(g)

Answer: 18.11 g C3H8 remaining

25.0 g of C3H8 – 6.9 g of C3H8 = 18.1 g C3H8 remaining

Citric acid (abbreviate as H3A for this problem) is a weak acid with the Ka and Kb values listed below. Calculate the equilibrium pH if 0.100 moles of sodium citrate (Na3A) are dissolved in 1.00 L

of water. Ka1 = 7.44 x 10-4

Ka2 = 1.73 x 10-5

Ka3 = 4.02 x 10-7

Kb1 = 2.49 x 10-8

Kb2 = 5.78 x 10-10

Kb3 = 1.34 x 10-11

Answer: 9.7

Kb1 Reaction: A3- + H2O HA2- + OH-

At Equilibrium: 100 – x x x(ignore x in the denominator)

X = [OH-] = 4.99 x 10-5 M

pOH = 4.3

pH = 14.0 – 4.3 = 9.7

Citric acid (abbreviate as H3A for this problem) is a weak acid with the Ka and Kb values listed below. Calculate the equilibrium pH if 0.100 moles of sodium citrate (Na3A) are dissolved in 1.00 L of water.

Ka1 = 7.44 x 10-4

Ka2 = 1.73 x 10-5

Ka3 = 4.02 x 10-7

Kb1 = 2.49 x 10-8

Kb2 = 5.78 x 10-10

Kb3 = 1.34 x 10-11

Answer: 9.7

Kb1 Reaction: A3- + H2O HA2- + OH-

At Equilibrium: 100 – x x x(ignore x in the denominator)

X = [OH-] = 4.99 x 10-5 M

pOH = 4.3

pH = 14.0 – 4.3 = 9.7