CHEM QUIZZES

Calculate the pH of a buffer that contains 1.2 M acetic acid, CH3COOH, and 0.9 M sodium acetate. Ka of acetic acid = 1.8 x 10-5 CH3COOH(aq) + H2O(l) ⇌ H3O+(aq) + CH3COO-(aq)

4.62

Calculate the frequency of light that has a wavelength of 630 nm. 1 nm = 1 x 10-9 m

4.76 x 10^14 s^-1

The concentration of carbon dioxide in air is 0.04%. Express the concentration of carbon dioxide in ppm.

400 ppm

A sample of drinking water contained 0.03 mg/L of lead ion. What is the concentration of lead ion in ppb? 1 mg = 1 x 10-3 g density of the solution = 1 g/mL **quiz 5**

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Add 10.0 g of salt (sodium chloride) to 80.0 mL (80.0 g) of water. What is the percent concentration of this solution? **quiz 5**

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How many moles of Ba(OH)2 are needed to neutralize 60.0 mL of a 1.06 M HCl solution? Ba(OH)2(aq) + 2HCl(aq) ⟶⟶ BaCl2(aq) + 2 H2O(l)

0.0318 mol Ba(OH)2

Calculate the wavelength of a radiation that has a frequency of 5.09 x 1014 Hz. 1 nm = 1 x 10-9 m

589mn

Arrange the following hydrocarbons in order of increasing vapor pressure. C15H32 C4H10 C8H18

C15H32 < C8H18 < C4H10

What is the chemical formula of the compound below?

C8H9NO2

What is the condensed structural formula of the compound below?

CH3CH(CH2OH)CH2CH2CH3

Calculate the mass of CO2 that contains 100 g of O.

138 g

Which molecule does exhibit hydrogen bonding?

CH3OH CH2F2 H2 CH3CN

Analysis of 200 L of air shows the volume of water is 0.006 L. Calculate the concentration of water

0.003%

Convert 2.4 x 10^-8 m to 𝜇μm. 1 𝜇μm = 1 x 10^-6 m

0.024 𝜇μm

Place the following electromagnetic waves in order of increasing energy. Infrared X-rays microwave

microwave < Infrared < X-rays

The mass defect of 39K is -9.52 x 10^-29 kg. Calculate the nuclear binding energy for 39K. Speed of light = 3.00 x 10^8 m/s

-8.57 x 10^-12 J

Which pair represents isomers?

on google doc

Choose a polar molecule below.

H2O CO2 H2 CCl4

What is the name of N2O4 ?

dinitrogen tetroxide

2.8 g of Ba(OH)2(s) is added to water to prepare a solution of 4.00 L. What is the pH of this solution? Molar mass of Ba(OH)2 = 171.3 g/mol?

pH=11.9

Which is a reduction half-reaction?

Cl2 + 2 e- → 2 Cl- 2 HCl + Ba(OH)2 → 2 H2O + BaCl2 2 H2 + O2 → 2 H2O Zn → Zn2+ + 2 e- CH4 + 2 O2 → CO2 + 2 H2O

A laboratory galvanic cell is shown below. A coating of impure copper metal begins to appear on the surface of the copper electrode as the

Cu(s)

What is the conjugate acid of CO32- in the reaction below? CO32- + HSO4- ⇌ HCO3- + SO42-

HCO3-

A NiCd battery uses nickel and cadmium to produce a potential difference. Which equation represents what takes place at the anode? I. 2NiO(OH) (s) + 2H2O (l) + 2 e- → 2Ni(OH)2 (s) + 2 OH- (aq) II. Cd (s) + 2OH- (aq) → Cd(OH)2 (s) + 2e- III. Cd (s) + 2NiO(OH) (s) + 2 H2O (l) → 2 Ni(OH)2 (s) + Cd(OH)2 (s)

II

Which square(s) contain(s) only an element?

II

Which compound(s) are correctly named? I. Cu(NO2)2 copper(II) nitrate II. (NH4)2SO4 ammonium sulfate III. PdPO4 palladium(I) phosphate IV. CaCO3 calcium carbonate

II and IV

Nitrogen gas reacts with hydrogen gas to form ammonia (NH3). Write a balanced chemical equation to represent the reaction. Hint: Nitrogen gas and hydrogen gas are diatomic molecules.

N2 + 3H2 ⟶ 2 NH3

Which compound should be the most soluble in hexane (C6H14)?

Octane, C8H18

A laboratory galvanic cell is shown below. A coating of impure copper metal begins to appear on the surface of the copper electrode as the cell discharges. What is the reaction taking place at anode?

Zn(s) → Zn2+(aq) + 2 e-

For the reaction 3H2(g) + N2(g) ⇌ 2NH3(g) , Keq = 0.297 at 700K. If [H2] = [N2] = [NH3] = 1.62 M at 700K, which one of the following is correct?

[H2] and [N2] increase as the system approaches equilibrium.

Which naturally occurring radioactive particles are the size of a helium nucleus?

alpha particles

What type of radiation is given off in this nuclear reaction? 14/6𝐶⟶14/7𝑁+?

beta

Which feature or process is unique to nuclear power plants when compared to conventional coal-burning power plants?

control rods

A cheeseburger contains 303 kcal (or Cal). Express this value in J. 1 cal = 4.184 J

1.27 x 10^6 J

Calculate the energy of one photon that has a frequency of 2.86 x 1015 s-1.

1.90 x 10^-18 J

Calculate the energy of a photon that has a wavelength of 780 nm. 1 nm = 1 x 10^-9 m

2.55 x 10^-19 J

What is the oxidation number of Fe in Fe2O3 ?

3

The mass of each proton and neutron is given in the table below. The measured mass of a 39K atom is 38.9637 amu. Calculate the mass defect. Nucleon Proton: Mass of each nucleon in amu - 1.007825 Neutron: Mass of each nucleon in amu- 1.008665

-0.3583 amu

Use the bond energies given below the calculate the heat of combustion for ethyne (also called acetylene), C2H2. Bond energies: C-H 416 kJ/mol O=O 498 kJ/mol 𝐶≡𝐶 813 kJ/mol C=O 803 kJ/mol O-H 467 kJ/mol

-2512 kJ

A water sample has a H+ concentration of 1.8 x 10-8 M. What is the concentration of hydroxide ions? Is the sample acidic or basic? **quiz 6**

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The pH of lemon juice is approximately 2.82. What is the concentration of hydrogen ions in the juice? **quiz 6**

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Which solution is most acidic? **quiz 6**

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Which statement about the oxidation-reduction reaction below is correct? 2Ag+(aq) + Zn (s) → 2Ag(s) + Zn2+(aq) **quiz 9**

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Choose the most polar bond below. **quiz 5**

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Which statement about combustion of octane is correct? 2C8H18 (l) + 25 O2(g) ⟶⟶ 16CO2 (g) + 18 H2O(l) ΔH = -10,123 kJ **quiz 7**

...

A sample of air contains 2.5 x 10^3 ppm water vapor. Express the concentration of water vapor in percent.

0.25%

Calculate Keq for the reaction 3H2(g) + N2(g) ⇌ 2NH3(g) given that the concentrations of each species at equilibrium are as follows: [N2] = 2.05 M, [H2] = 1.56 M, and [NH3] = 1.52 M.

0.297

How many moles are in 87.2 g of calcium sulfate, CaSO4?

0.641 mol

Draw a Lewis structure of SO2 that follows the octet rule. How many single bonds, double bonds, and nonbonding (or lone pair) electrons are around the atom S?

1 Single bond, 1 double bond, and 2 lone pair electrons around S

Convert 130.0 nm to m. Pay attention to the significant figures. 1 nm = 1 x 10^-9 m

1.300 x 10^-7 m

What is the resistance of a circuit with 120 V and 5 A?

24 Ω

If you have 200.0 g of radioisotope with a half-life of 5 days, how much isotope would remain after 15 days?

25.0 g

One of the lightest smartphones on the market today weighs 113.0 g. To protect your phone, you may want to use a screen protector, which weighs 27.20 g, and a heavy-duty phone case, which weighs 114 g. What is the total weight of the phone, screen protector, and case? Please pay attention to significant figures.

254 g

The experimentally determined heat of combustion of ethanol is 1233 kJ/mol. Calculate the heat of combustion of ethanol in kJ/g. Molar mass of ethanol C2H5OH = 46 g/mol C2H5OH(g) + 3 O2(g) → 2 CO2 (g) + 3 H2O(l) ΔΔH = -1233 kJ/mol

26.8 kJ/g

Choose the total ionic equation of the neutralization reaction of hydrochloric acid HCl and barium hydroxide Ba(OH)2.

2H+(aq) + 2Cl-(aq) + Ba2+ (aq) + 2OH-(aq) → Ba2+ (aq) + 2Cl-(aq) + 2H2O(l)

Choose the molecular equation of the neutralization reaction of hydrochloric acid HCl and barium hydroxide Ba(OH)2.

2HCl(aq) + Ba(OH)2(aq) → BaCl2(aq) + 2H2O(l)

Balance the chemical equation below with smallest whole numbers. What is the coefficient for O2? ____ S + __?__ O2 ⟶⟶ ____ SO3

3

How many electron groups are around S in the molecule SO2? What is the bond angle O-S-O in the molecule SO2?

3 electron groups, less than 120°

How many molecules are in 87.2 g of calcium sulfate, CaSO4?

3.86 x 10^23 molecules

When atoms of aluminum-27 are bombarded with alpha particles, a neutron and an element are produced. What is the particular isotope formed? 4/2𝐻𝑒+27/13𝐴𝑙⟶1/0𝑛+?

30/15 P

6,960 J of heat is absorbed by 150 g of water at 20.2°C. What is the final temperature (in °C) of the water? The specific heat of water is 4.184 J/g°C

31.3°C

One common class of minerals are aluminosilicates, with a general formula of Al2SiO5. What is the mass percentage composition of aluminum in an aluminosilicate?

33.3%

How many electron groups are around P in the molecule PCl3? What is the shape of the molecule PCl3?

4 electron groups, trigonal pyramidal

Draw a Lewis structure of H2O that follows the octet rule. How many nonbonding (or lone pair) electrons are around the atom oxygen?

4 lone pair electrons

Balance the chemical equation below with smallest whole numbers. What is the coefficient for O2 ? C2H2(g) + O2(g) ⟶⟶ CO2(g) + H2O(l)

5

Calculate the heat released when 128 grams of octane, C8H18, burns. Molar mass of octane = 114 g/mol 2 C8H18 (g) + 25 O2(g) → 16 CO2 (g) + 18 H2O(l) ΔΔ H = -10,123 kJ

5.67 x 103 kJ

Calculate the volume of the box. The length of the box is 24.0 cm, width 120.5 cm, height 2.0 cm. Pay attention significant figures.

5.8 x 10^3 cm^3

Express the number 0.06200 g in scientific notation.

6.200 x 10^-2 g

The volume of a gas mixture containing helium, neon, and argon is 80.0 L. The concentration of helium is 8.21%. Calculate the volume of helium in this mixture.

6.57 L

What is the mass of 4.80 x 10^20 atoms of Kr? NA = 6.02 x 10^23

6.68 x 10^-2 g

To prepare 4.00 L of the 1.20 M CuSO4 solution, how many grams of CuSO4 are needed? Molar mass of CuSO4 = 159.62 g/mol

766 g

How many nonbonding (or lone pair) electrons are in the Lewis structure of CO2?

8

Element X has two naturally occurring isotopes. X-84 has a mass of 83.912 amu and an abundance of 72.17%. X-86 has a mass of 86.046 amu and an abundance of 27.83%. What is the average atomic mass of this element? Isotopes 84^ X 86^X Mass (amu) 83.912 86.046 Abundance 72.17% or 0.7217 27.83% or 0.2783

84.506 amu

A piece of copper weighted 35.2 g is cooled down from 90.2°C to 27.4°C. How much heat (in J) is released from the copper? The specific heat of copper is 0.385 J/g ∘∘C.

851 J

How many protons, neutrons, and electrons are there in a neutral atom of 19F?

9 protons, 10 neutrons, 9 electrons

How much energy is created from the conversion of 0.10 g of matter? speed of light = 3.0 x 108 m/s

9.0 x 10^12 J

What is the chemical equation for the dissociation of aluminum hydroxide?

Al(OH)3 ⟶ Al3+ + 3 OH-

Write the equilibrium constant expression for the following reaction: 2Fe(s) + 3H2O(l) ⇌ Fe2O3(s) + 2H2(g)

𝐾𝑒𝑞=[𝐻2]^2