Chem 103 All Exams (1-4)

Argon and Helium gases are separated into two sides of a reaction chamber as seen below. The valve is opened and the two gases are allowed to mix. What is the pressure inside the vessel (in atm) after the two gases mix? Gas A: Argon. Volume = 551 mL, P = 1.6 atm, T = 25°C Gas B: Helium. Volume = 725 mL, P = 3.4 atm, T = 25°C

*2.62 atm* Explanation: Step 1: Ar: V = 0.551 L, P = 1.6 atm, T = 298.15 K He: V = 0.725 L, P = 3.4 atm, T = 298.15 K 0.725 L + 0.551 L = 1.276 L Step 2: VHe(i) x PHe(i) = VHe (F) x PHe (F) (0.725 L) (3.4 atm) = (1.276 L) (PHeF) PHe(F) = 1.932 atm Step 3: VAr(i) x PAr(i) = VAr (F) x PAr (F) (0.551 L) (1.6 atm) = (1.276 L) (PArF) PAr(F) = 0.691 atm Step 4: Ptotal = 1.932 + 0.691 = 2.62 atm

A student wrote out a chemical equation based on the following description: Magnesium metal reacts with nitrogen in the air to produce the ionic compound magnesium nitride. The following equation was submitted: 3 Mg (l) + 2 N (g) ---> Mg3N2 (s) Mark all of the mistakes made by the student from the following: A) The formula for magnesium nitride is incorrect B) The 2 N (g) is on the wrong side of the equation C) Nitrogen exists as a diatomic element D) Nitrogen exists as a solid E) Magnesium exists as a solid

*C) Nitrogen exists as a diatomic element* and *E) Magnesium exists as a solid*

The specific heat of copper is 0.387 J/g°C and the specific heat of silicon is 0.703 J/g°C. Choose the correct drop down to complete the paragraph. The element _____ will have a larger increase in temperature when heat is applied given that the two have the same mass and starting temperature. This is because it has a ________ specific heat. The change in temperature and the specific heat are _________ proportional.

*copper*, *smaller*, *inversely*

Consider the following reaction: 2 Mg + O2 → 2 MgO △H rxn = -1203 kJ Calculate the amount of heat (in kJ) associated with complete reaction of 4 moles of Mg.

-2406 kJ

If 0.328 moles of iron and 0.623 moles of sulfur react to form iorn (III) sulfide, how many moles of the EXCESS reactant will be left over when the reaction is complete? 2Fe (s) + 3S (s) ---> Fe2S3 (s)

0.131

How many significant digits should be reported in the answer to the following calculation? (4.3 - 3.7) × 12.3 = _______

1

Match the number to the correct number of significant figures. 1) *3 significant figures* 2) *1 significant figure* 3) *2 significant figures* 4) *4 significant figures*

1) *0.0103* 2) *0.01* 3) *9.0* 4) *74.00*

Balance the following aqueous ionic equations. If the coefficient is 1, include it for this problem. 1) MgCl2 (aq) ---> ____ Mg^2+ (aq) + ____ Cl^- (aq) 2) Na2CO3 (aq) ---> ____ Na^+ (aq) + ____ CO3^2- (aq) 3) Cr2(SO4)3 (aq) ---> ____ Cr^3+ (aq) + ____ SO4^2- (aq)

1) *1*, *2* 2) *2*, *1* 3) *2*, *3*

Perform the following temperature conversions (report your answers to the proper decimal place): 1) 23.5 °C = _______°F 2) 105 °F = ______°C 3) 355 K = ______°F

1) *74.3* 2) *40.6* 3) *179*

Fill in the table by performing the appropriate conversion and using the proper number of significant figures (use 4 sig figs for the molar mass). NOTE: There are three problems here. Use the information in each ROW to fill in the missing information for that row. Compound, molar mass (g/mol), mass (g), number of moles 1) MgCl2, ______, 13.65, ______ 2) Al(OH)3, _______, _______, 0.00765 3) Cr2O3, _______, 0.5, _______

1) *95.21*, 0.1434* 2) *78.00*, *0.597* 3) *151.9*, *0.003*

Is the following a description of a mixture, an element, or a compound? 1) A uniform, solid, red, substance that cannot be decomposed. 2) A colorless liquid with two distinct boiling points 3) A substance made of two or more different elements

1) *Element* 2) *Mixture* 3) *Compound*

(Picture of a graph showing reactants having a HIGHER energy than products) 1) The energy diagram above shows an __________ reaction. The sign of H in this reaction is __________. This means that energy is _________ in this process. 2) In the reaction Sn (s) + 2 S (s) ---> SnS2 (s) ; △H = -154 kJ/mol 3.6 moles of sulfur and excess tin would produce _______ kJ of energy.

1) *exothermic*, *-*, *released* 2) *280*

Report the following to the correct number of significant figures (standard notation): 1) The number of cups in 45.6 L = ______ cups 2) The number of dm in 0.678 km = ______ dm 3) The number of grams in a 267.6 lb person = ______ g

1) 193 2) 6780 3) 121400

Match the scientist to the discovery that he made about the arrangement of the subatomic particles in the atom. 1) Used the Cathode Ray Tube to discover the electron 2) Ran the Gold Foil experiment to discover a dense inner region called the nucleus 3) Used charged oil drops to find the charge to mass ratio of the electron

1) JJ Thomson 2) Earnest Rutherford 3) Robert Millikan

Write the name of the following compound or provide the formula. NOTE for formulas, you will not be able to use subscripts. Just use them as standard numbers. EX. aluminum nitrate would be Al(NO3)3 1) sodium oxalate , _________ 2) _________ , MnO2 3) dihydrogen monoxide , _________ 4) __________ , H2CO3 (aq)

1) Na2C2O4 2) manganese (IV) oxide 3) H2O 4) carbonic acid

Determine whether the following are chemical or physical properties of ethanol. 1) *Ethanol is soluble (dissolves) in water* 2) *Ethanol is combustible* 3) *Ethanol can be converted to vapor with applied heat* 4) *Ethanol has a density of 0.789 g/mL* 5) *Ethanol can be produced by fermenting sugars with yeast*

1) Physical 2) Chemical 3) Physical 4) Physical 5) Chemical

Provide the name of he polyatomic ion listed below: Polyatomic Ion , Name 1) OH- , __________ 2) CN- , __________ 3) ClO- , __________ 4) PO3^3- , __________ 5) CrO4^2- , __________ 6) C2O4^2- , __________

1) hydroxide 2) cyanide 3) hypochlorite 4) phosphite 5) chromate 6) oxalate

Complete and balance the following reactions: (Do your best with formatting using subscripts and superscripts. There is an option to use these in the text editor tool but it is not required. For example, you can type H2O or H2O for this question). 1. Na3PO4 (aq) + CaI2 (aq) ---> 2. (NH4)2SO4 (aq) + CuCl2 (aq) ---> 3. Ba(OH)2 (aq) + HCl (aq) --> 4. BaCl2 (aq) + K2CO3 (aq) -->

1. 2Na3PO4 (aq) + 3CaI2 (aq) --> Ca3(PO4)2 (s) + 6NaI (aq) 2. (NH4)2SO4 (aq) + CuCl2 (aq) --> 2NH4Cl (aq) + CuSO4 (aq) = No Reaction 3. Ba(OH)2 (aq) + 2HCl (aq) --> BaCl2 (aq) + 2H2O (l) 4. BaCl2 (aq) + K2CO3 (aq) --> BaCO3 (s) + 2KCl (aq)

Consider the following double displacement reaction: AlCl3 (aq) + 3 AgNO3 (aq) ---> 3 AgCl (s) + Al(NO3)3 (aq) Answer the following questions based on the above. 1. The general name for the solid product formed in a double displacement reaction is ________. 2. The _______ cation is a spectator ion in this reaction. (Use the ion name, not the symbol). 3. The ________ cation and the _________ anion are NOT spectator ions in this reaction. (Use the ion name, not the symbol).

1. precipitate 2. aluminum 3. silver, chloride

Consider the following reaction:Cu (s) + 4HNO3 (aq) --> 2NO2 (g) + 2H2O (l) + Cu(NO3)2 (aq)If 1.51 g of copper are placed into excess nitric acid, how many liters of nitrogen dioxide gas can be produced at 20.2 oC and 764 torr?

1.14 L NO2 Explanation: Step 1: ?mol NO2 = 1.51g Cu (1mol Cu/63.55g Cu) (2 mol NO2/1 mol Cu) = 0.04752 mol NO2 Step 2: V = NRT/PV = (0.04752 mol) (0.0821 Lxatm/molxk) (293.35 K) / (764/760) V = 1.14 L NO2

Suppose it took 108 joules of energy to raise a bar of gold from 25.0°C to 29.7°C. Given that the specific heat capacity of gold is 0.128 J/g°C, what is the mass (in grams) of the bar of gold?

1.8 × 10^2 g

Determine the answer to the following equation with correct number of significant figures: 2.02 + 8.102 - 0.0297 = ________

10.09

An iron ore sample is found to be 35.00% Fe by mass. How many grams of ore are needed to obtain 454.0 grams of Fe?

1297

An atom that has the same number of neutrons as 138/56 Ba is:

136/54 Xe

An unknown element has three isotopes as follows: Isotope Mass , % Abundance 153.9 amu 25.25% 159.7 amu 33.65% 161.9 amu 41.10% What is the atomic mass of the unknown element (do not include the units)?

159.1

How many waffles can be made from 1 dozen eggs, assuming you have enough of all other ingredients? Given: 2 cups flour + 3 eggs + 1 tbs oil → 4 waffles

16

A 42.7 gram sample of potassium nitrate contains how many grams of potassium?

16.5

Determine the answer for the equation below with correct number of significant figures: 3.215 × 13.2 ÷ 0.218 = ________

195

How many subshells are there in the n = 2 principal shell?

2

What are the coefficients for the following reaction when it is properly balanced? ___potassium iodide + ___lead (II) acetate → ___lead (II) iodide +___potassium acetate

2, 1, 1, 2

How many cm3 are there in 2.5 m3?

2.5 x 10^6

Consider the following reaction: 4 Cr (s) + 3 O2 (g) ---> 2 Cr2O3 (s) If 6.02 g of chromium are used in the above reaction, how many grams of oxygen would also be needed in the reaction?

2.78

A compound is 47.35% carbon by mass, 10.60% hydrogen by mass and 42.05% oxygen by mass. What is the empirical formula? (Enter the subscript for that element into the box next to the element). C____H____O____

3, 8, 2

Given that 4 NH3 + 5 O2 → 4 NO + 6 H2O, when 4.50 mol of H2O are formed, the amount of NO formed is

3.00 mol

What is the value of 27°C on the Kelvin temperature scale?

300

If the theoretical yield of a reaction is 42.0 grams of product and the percent yield is 75%. How many grams were actually produced?

32

How many electrons are in Br-?

36

The correct number of significant figures in the number 0.002320 is:

4

When methane is burned with oxygen, the products are carbon dioxide and water. If you produce 9 grams of water and 11 grams of carbon dioxide from 16 grams of oxygen, how many grams of methane were needed for the reaction?

4

When the equation __NO2 + __H2O + __O2 → __HNO3 is balanced, the coefficient of HNO3 is

4

One mole of potassium sulfate contains:

4 moles of oxygen

Balance the following reaction by placing the coefficient in the blank. NOTE: If the coefficient is "1" for that molecule or element, place a "1" in the box. ____ Si2H3 + ____ O2 --> ____ SiO2 + ____ H2O

4, 11, 8, 6

If 3.011 × 1023 molecules have a mass of 20.04 grams, what is the molar mass of this substance?

40.08 g/mol

The correct scientific notation for the number 0.00050210 is:

5.0210 × 10^-4

How many moles of aluminum are needed to make 9 moles of molecular hydrogen? Given the reaction: 2 Al + 6 HCl → 2 AlCl3 + 3H2

6 moles

How many valence electrons are in a chlorine atom?

7

Consider the following reaction: C4H10O + 6 O2 → 4 CO2 +5 H2O If a reaction vessel contains 1.8 moles of C4H10O and 22.8 moles of O2, how many moles of CO2 can be produced?

7.2

Find the density of an object (in g/mL) that weights 14.844 kg and has a volume of 8.8 cups. (Do not include the units in your answer and report your answer to the correct number of significant figures).

7.2

How many grams of chlorine gas are needed to make 117 grams of sodium chloride? Given the reaction: 2Na + Cl2 → 2NaCl

71.0

A 8.75 g sample of aluminum (0.900 J/goC) at 27.4°C is heated to 127°C. How many joules of heat energy did the sample gain? Do not include units in your answer and report your answer to the correct number of significant figures.

784

When the equation, ___O2 + ___C5H12 → ___CO2 + ___H2O is balanced, the coefficient:of O2 is:

8

A fictional element has two isotopes and an atomic mass of 87.08 amu. If the first isotope is 86 amu and the second isotope has a mass of 90 amu. Which isotope has the greatest natural abundance?

86 amu

Calculate the molar mass of ammonium carbonate.

96.09 g/mol

A rectangular prism has dimensions of 161.3 in x 62.8 in x 599.8 in. Find the volume of the prism in units of m3. Do not include the units in your answer.

99.6

Which one of the following species has the electron configuration of 1s^2 2s^2 2p^6? 1. Na+ 2. O^2- 3. F- A) All of 1, 2, and 3 B) 1 and 2 only C) 1 and 3 only D) Neither 1, 2, or 3 E) 2 and 3 only

A) All of 1, 2, and 3

Draw the Lewis Structure for the thiocyanate ion (SCN-) and answer the following questions: A) The central atom in the molecule is ________. B) This molecule has a ________ molecular shape. C) The polarity of this molecule is ____________. D) This molecule has _______ total resonance structures. E) In order to have resonance structures, a molecule must have __________.

A) Carbon B) Linear C) Polar D) 3 E) two or more valid Lewis Structures

Identify the type of reaction below: A) H2CO3 (aq) ---> H2O (l) + CO2 (g) B) CaO (s) + CO2 (g) ---> CaCO3 (s) C) Mg (s) + ZnSO4 (aq) ---> Zn (s) + MgSO4 (aq)

A) Decomposition B) Combination C) Single Displacement

Which form of electromagnetic radiation has the shortest wavelength? A) Gamma Rays B) Radio Waves C) Microwaves D) X-rays E) Infrared Radiation

A) Gamma Rays

Which of the following would NOT be a product from mixing hydrochloric acid with a solution of sodium sulfite? A) H2 (g) B) H2O (l) C) SO2 (g) D) NaCl (aq) E) none of the above

A) H2 (g)

Which statement below does NOT follow the Bohr Model? A) The energy emitted from a relaxing electron can have any wavelength. B) none of the above C) When an atom emits light, electrons fall from a higher orbit into a lower orbit. D) Electrons exist in specific, quantized orbits. E) When energy is absorbed by atoms, the electrons are promoted to higher-energy orbits.

A) The energy emitted from a relaxing electron can have any wavelength.

Suppose a boat engine leaks 938 milliliters of oil into a lake. The mass of this spilled oil is 823 grams. The oil will not mix with the lake water. Which statement is true? A) The oil will float because its density of 0.877 g/mL is less than the density of water. B) The oil will float because its density of 1.14 g/mL is less than the density of water. C) The oil will sink because its density of 0.877 g/mL is greater than the density of water. D) The oil will sink because its density of 1.14 g/mL is greater than the density of water. E) none of the above

A) The oil will float because its density of 0.877 g/mL is less than the density of water.

How would you classify raisin bran? A) mixture-heterogeneous B) pure substance-element C) pure substance-compound D) mixture-homogeneous E) none of the above

A) mixture-heterogeneous

If you hold a solid piece of pure gallium metal in your hand, your body heat will melt the gallium into its liquid form. This illustrates which of the following? A) physical change B) chemical change C) chemical property D) distillation E) none of the above

A) physical change

What is the atomic symbol for silver?

Ag

A 7.96 gram sample of silver reacts with oxygen to form 8.55 gram of the metal oxide. What is the formula of the oxide?

Ag2O

Fill in the blank with the element (name or symbol) the configuration or the diagram represents. 1s^2 2s^2 2p^6 3s^2 3p^1

Al

(picture of periodic table) The name of the family of elements designated as column 1 is _________. The elements that make up column 18 are the _________. All of the elements in columns 3-12 are called _________. The elements in column 2 are called _________ and the elements of column 17 are the _________. Finally, the elements of column 16 are called _________.

Alkali Metals, Noble Gases, Transition Metals, Alkaline Earth Metals, Halogens, Chalcogens

Who discovered the law of conservation of mass?

Antoine Lavoisier

Match the description to the gas law. *A balloon filled with 0.5 moles of gas has a volume of 2.0 L. If 0.5 moles of gas are added to the balloon, the volume is now 4.0 L.*

Avogadro's Law

An accepted abbreviation format is to write an electron configuration that includes a noble gas symbol in brackets. If you were writing an electron configuration for a bromine atom, which elemental symbol would you place in the bracket? A) Ne B) Ar C) Xe D) Kr E) He

B) Ar

Which metal atom below would NOT be involved in formation of a Type II compound? A) Cr B) Ba C) Fe D) Mn E) none of the above

B) Ba

Which of the following compounds is SOLUBLE? A) aluminum carbonate B) aluminum sulfate C) aluminum hydroxide D) aluminum sulfide E) none of the above

B) aluminum sulfate

Chlorine and bromine have very similar chemical properties. This is best explained by the fact that both elements. A) are in period 3 of the Periodic Table B) have the same number of valence electrons C) are gases D) none of the above E) have equal number of protons and electrons

B) have the same number of valence electrons

Match the description to the gas law. *If pressure increases, volume decreases.*

Boyle's Law

You have 10.0 g each of Na, C, Pb, Cu and Ne. Which contains the largest number of moles?

C

Which formula shown is incorrect for the name given? A) calcium carbonate: CaCO3 B) potassium hydroxide: KOH C) magnesium nitrite: Mg(NO2)3 D) aluminum sulfate: Al2(SO4)3 E) sodium hydrogen carbonate: NaHCO3

C) magnesium nitrite: Mg(NO2)3

What is the excess reactant for the following reaction given we have 2.6 moles of HCl and of Ca(OH)2? Reaction: 2HCl + Ca(OH)2 → 2H2O + CaCl2

Ca(OH)2

Match the description to the gas law. *Pressure and number of moles are held constant while temperature and volume change.*

Charles' Law

A pure substance is: A) composed of two or more different types of atoms or molecules that has constant composition. B) composed of two or more different types of atoms or molecules combined in variable proportions. C) composed of two or more regions with different compositions. D) composed of only one type of atom or molecule. E) none of the above

D) composed of only one type of atom or molecule.

What is the molecular formula of a compound given the molar mass of the compound is 186.5 grams and the empirical formula is C2H7? A) C2H14 B) C4H14 C) C3H21 D) C2H7 E) none of the above

E) none of the above

Which one of the following is the correct orbital diagram for nitrogen? A) ⇅ ⇊ ↑ ↑ ↑ B) ⇅⇊↓ ↑ ↑ C) ⇅ ↑↓ ↓ ↓ ↑ D) none of the above E) ⇅ ↑↓ ↑ ↑ ↑

E) ⇅ ↑↓ ↑ ↑ ↑

Match the description to the gas law. *P1/T1 = P2/T2*

Gay-Lussac's Law

A certain oxyacid is derived from the oxyanion SO3^2-. The formula for the oxyacid is

H2SO3-

Fill in the blank with the element (name or symbol) the configuration or the diagram represents. {Xe}6s^2 4f^14 5d^10

Hg

Fill in the blank with the element (name or symbol) the configuration or the diagram represents. 1s^2 2s^2 2p^4

O

Considering the following precipitation reaction: Pb(NO3)2(aq) + 2KI(aq) → PbI2(s) + 2KNO3(aq) What is the correct complete ionic equation?

Pb^2+ + 2NO3^- + 2K^+ + 2I^- → PbI2(s) + 2K^+ + 2NO3^-

Fill in the blank with the element (name or symbol) the configuration or the diagram represents. {Kr}5s^2 4d^6

Ru

The carbon numbered "1" above has a _________ molecular geometry. The carbon numbered "2" above has a ________ molecular geometry. The oxygen numbered "3" has a _______ molecular geometry. The numbered atom will be your central atom, so just base your response on it.

Tetrahedral trigonal planar bent

What is the definition of a scientific theory?

a model that explains the underlying reasons for observations and laws

Find the mole of each element for the following (express all responses to three significant figures and do not include the unit): a. Moles of carbon in 0.552 moles of CaCO3 _______ b. Moles of oxygen in 1.34 moles of FeSO4 ___________ c. Moles of nitrogen in 0.0786 moles of calcium nitrate __________

a. 0.552 b. 5.36 c. 0.157

What is the name of Ca(NO3)2?

calcium nitrate

A reaction in which a substance reacts with oxygen, emitting heat and forming oxygen-containing compounds is an example of a(n)

combustion reaction

Consider the following single displacement reaction: Cu (s) + 2 AgNO3 (aq) ---> Cu(NO3)2 (aq) + 2 Ag (s) The element being oxidized in the above reaction is _______. In oxidation, electrons are ______. The element being reduced is ________. In reduction, electrons are _______.

copper, lost, silver, gained

The size of an atom generally increases

down a group and from right to left across a period

What type of a reaction occurs when a potassium nitrate solution is mixed with a barium acetate solution?

no reaction

Group 8A elements are also called:

noble gases

Which subshell letter corresponds to a spherical orbital?

s

What term best describes a brief statement that summarizes many past observations and predicts new ones?

scientific law

What is the name of the molecular compound SO3?

sulfur trioxide