chemistry questions powerpoint

46
2010- 1A12 a. What is the name given to a compound containing a COOH functional group? b. Name the following compound: CH 3 COOH

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Page 1: 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

Page 2: 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

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

Page 3: Chemistry questions powerpoint

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

Page 4: Chemistry questions powerpoint

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

Page 5: Chemistry questions powerpoint

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

Page 6: Chemistry questions powerpoint

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

-).

Page 7: Chemistry questions powerpoint

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)

Page 8: Chemistry questions powerpoint

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)

Page 9: Chemistry questions powerpoint

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)

Page 10: Chemistry questions powerpoint

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

Page 11: Chemistry questions powerpoint

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

Page 12: Chemistry questions powerpoint

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

Page 13: Chemistry questions powerpoint

2010-1C18

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

H2N C

H

H

C

O

OH

Page 14: Chemistry questions powerpoint

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

Page 15: Chemistry questions powerpoint

2010-2A12

What is the common name for acetylsalicylic acid?

Page 16: Chemistry questions powerpoint

2010-2A12

What is the common name for acetylsalicylic acid?

Answer: Aspirin

Page 17: Chemistry questions powerpoint

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?

Page 18: Chemistry questions powerpoint

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

Page 19: Chemistry questions powerpoint

2010-2A15

What is the name of the polyatomic anion MnO4

- ?

Page 20: Chemistry questions powerpoint

2010-2A15

What is the name of the polyatomic anion MnO4

- ?

Answer: Permanganate

Page 21: Chemistry questions powerpoint

2010-2A18

What element has 10 protons?

Page 22: Chemistry questions powerpoint

2010-2A18

What element has 10 protons?

Answer: Neon

Page 23: Chemistry questions powerpoint

2010-2C12

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

Page 24: Chemistry questions powerpoint

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

Page 25: Chemistry questions powerpoint

2010-2C15

Which element in the periodic table has the largest electronegativity?

Page 26: Chemistry questions powerpoint

2010-2C15

Which element in the periodic table has the largest electronegativity?

Answer: Fluorine or F

Page 27: Chemistry questions powerpoint

2010-2C17

The oxygen released during photosynthesis originates from what

compound?

Page 28: Chemistry questions powerpoint

2010-2C17

The oxygen released during photosynthesis originates from what

compound?

Answer: Water (H2O)

Page 29: Chemistry questions powerpoint

2010-2C18

What is the oxidation number of carbon in formaldehyde?

O

C

H H

Page 30: Chemistry questions powerpoint

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.

Page 31: Chemistry questions powerpoint

2010-3A13

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

periodic table?

Page 32: Chemistry questions powerpoint

2010-3A13

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

periodic table?

Answer: Alkaline Earth Metals

Page 33: Chemistry questions powerpoint

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

Page 34: Chemistry questions powerpoint

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!!!!

Page 35: Chemistry questions powerpoint

2010-1B32

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

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

Page 36: Chemistry questions powerpoint

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)]

Page 37: Chemistry questions powerpoint

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.

Page 38: Chemistry questions powerpoint

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

Page 39: Chemistry questions powerpoint

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.

Page 40: Chemistry questions powerpoint

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

Page 41: Chemistry questions powerpoint

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.

Page 42: Chemistry questions powerpoint

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

Page 43: Chemistry questions powerpoint

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)

Page 44: Chemistry questions powerpoint

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

Page 45: Chemistry questions powerpoint

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

Page 46: Chemistry questions powerpoint

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