final
The oxidation number of lithium in Li⁺ is
1
What mass of precipitate (in g) is formed when 53.1 mL of 0.500 M AlCl₃ reacts with excess AgNO₃ in the following chemical reaction? AlCl₃(aq) + 3 AgNO₃(aq) → 3 AgCl(s) + Al(NO₃)₃(aq)
11.4 g 53.1mL AlCl3 × (0.50 mol AlCl3 /1000mL AlCl3) × (3 mol AgCl /1 molAlCl3) × (143.32g AgCl / 1mol AgCl) = 11.4 g AgCl
How many molecules are in 36.1 moles of CO₂?
2.17 × 10²⁵ molecules 36.1 mol CO2 × 6.022×10^23 molecules CO2/1 mol CO2 =2.17×10^25 molecules CO2
If 35.0 g of CH₃OH (MM = 32.0 g/mol) are dissolved in 500.0 mL of solution, what is the concentration of CH₃OH in the solution? A) 0.0700 M B) 2.18 M C) 0.00218 M D) 0.458 M
2.18 M (35.0g / 500mL) × (1mol/32.04g) × (1000mL/1L)= 2.18M
If 2.25 moles of H₂ and 1.55 moles of O₂ react how many moles of H₂O can be produced in the reaction below? 2 H₂(g) + O₂(g) → 2 H₂O(g)
2.25 mol .The limiting reactant can be determined by calculating the amount of the other reactant that would be necessary for the reaction to occur. H₂ is the limiting reactant because there isn't enough of it to completely react with the amount of O₂. The amount of other products and reactants can be found using the amount of H₂ and mole to mole ratios.
Determine the number of atoms of O in 46.5 moles of Fe₂(SO₃)₃.
2.52 × 10²⁶ atoms 46.5 mol Fe2( SO3)3 × 9 mol O/1 mol Fe2( SO3)3 × 6.022×10^23 atoms O/1 mol O =2.52×1026 atoms O
Calculate the answer and report the correct number of significant figures. 3.24 m x 7.0 m
23 m² When multiplying or dividing, the number with the least amount of significant figures determines how many significant figures the final answer should have. Since 3.24 has 3 significant figure2 and 7.0 has 2 significant figures, the answer to this part of the calculation should have 2 significant figures.
Consider chlorine, which occurs as a mixture of two isotopes: chlorine-35, with a natural abundance of 75.8% and an exact mass of 34.97 amu and chlorine-37, with a natural abundance of 24.2% and an exact mass of 36.97 amu. What is the average atomic mass of chlorine?
35.45 amu (34.97 amu × 0.758)+(36.97 amu × 0.242)= 35.45 amu
The number 917.00 has ___ significant figures.
5
Express the number 554,780,000,040 in scientific notation to three significant figures. A) 5.54 × 10¹¹ B) 5.55 × 10¹² C) 5.55 × 10¹¹ D) 5.548 × 10¹²
5.55 × 10¹¹
Which of the following compounds exhibits both ionic and covalent bonding? A) CaSO₃ B) SO₃ C) S₃Cl₂ D) CoS
CaSO₃ Ionic bonds occur between a metal and a nonmetal. Covalent bonds occur between two nonmetals.
How many electrons are in a neutral ⁴¹Ca atom? A) 2 B) 20 C) 21 D) 41
Calcium has 20 protons. Therefore a neutral calcium atom has 20 electrons.
What gas law states that pressure and temperature are directly proportional at constant volume and moles? A) Boyle's Law B) Charles' Law C) Gay-Lussac's Law D) Avogadro's Law E) Combined Gas Law
Gay-Lussac's Law P1/T1=P2/T2
What solid would form when phosphoric acid (H₃PO₄) is added to milk of magnesia (Mg(OH)₂)?
Mg₃(PO₄)₂
Classify the following compound as molecular or ionic: SiO₂ A) Molecular B) Ionic
Molecular Silicon dioxide, SiO₂, is a molecular compound composed of two or more nonmetals with covalent bonds between the silicon and the oxygen.
If the pressure on a movable piston of a closed container is doubled, what will happen?
Temperature will increase and volume will decrease, but the specific amount of each cannot be determined with the given information. (P1V1/T1)=(P2V2/T2) If the pressure of a container is doubled, then volume must decrease and temperature increase; however to know the specific amounts of change, more information would be required.
What is the element symbol for titanium? A) Tm B) Ti C) Ta D) Tn E) T
Ti
Which of the following states of matter is pictured below?
gas
Raw milk contains water, casein, as well as milkfat. Cream rises to the top of the milk, where it can be skimmed off, leaving behind skim milk. Raw milk is an example of a ______. A) mixture of elements B) homogeneous mixture (solution) C) molecular compound D) heterogeneous mixture
heterogenous mixture
What element has the symbol Ag? A) argon B) silver C) gold D) arsenic E) astatine
silver
What does the mass number of an atom represent? A) number of neutrons in the atom B) number of protons in the atom C) atomic mass of the element D) total number of electrons and neutrons in the atom E) total number of protons and neutrons in the atom
total number of protons and neutrons in the atom
The uncertainty in the measurement 13.560 mg is A) ± 0.1 mg B) ± 0.01 mg C) ± 0.001 mg D) ± 0.0001 mg
± 0.001 mg
What is the mass number of tin-113?
113 Isotopes can be written as "element-mass number". For example, "tin-120" indicates an atom of tin with a mass number of 120.
A thermometer reads 21.7 °C. What is the temperature in Kelvin?
294.9 .The formula to convert Celsius to Kelvin is: K=°C+273.15
Convert 18.0 gallons to deciliters. (3.7854 liters = 1 gallon)
681 dL 1L = 10dL
Determine the number of protons (p) and electrons (e) in N³⁻. A) 10 p, 7 e B) 7 p, 10 e C) 7 p, 7 e D) 7 p, 9 e E) 10 p, 10 e
7 p, 10 e
What is the correct formula for barium phosphate? A) BaPO₄ B) Ba₂PO₄ C) Ba₂(PO₄)₃ D) Ba₃(PO₄)₂
Ba₃(PO₄)₂
The uncertainty in the measurement 1500 m is A) ± 1000 m B) ± 100 m C) ± 10 m D) ± 1 m
± 100 m The last significant digit of a measurement is uncertain and its place value is used in the uncertainty. For example, the 5 in the hundreds place in 1500 is uncertain, yielding an uncertainty measurement of ± 100.
What is the atomic symbol and mass number for an atom containing 50 protons and 64 neutrons? A) ⁵⁰Sn B) ¹¹⁴Sn C) ⁶⁴Sn D) ⁶⁴Gd E) ¹¹⁴Gd
¹¹⁴Sn The mass number of an atom is representative of the number of protons and neutrons.
The number -1.025 × 10⁻³ when taken out of scientific notation would be A) -1025 B) 0.001025 C) -0.001025 D) 1025
-0.001025
The oxidation number of the nitrogen atom in NH₃ is
-3 Hydrogen has an oxidation number of +1 when combined with nonmetals. Multiply the number of hydrogen by its oxidation number. Add the oxidation numbers of all atoms together and set equal to the charge on the molecule, which is zero. The oxidation number of nitrogen can then be calculated. For NH₃ N+(3×(+1))=0 N=−3
What quantity in moles of HCl are there in 38.1 mL of 0.350 M HCl?
0.0133 mol 35.0mL × (1L / 1000mL) × (0.350mol/1L) =0.0123mol
What volume (in L) of 1.20 M FeCl₂ would be required to obtain 0.710 moles of Cl⁻ ions?
0.296 L (0.710 mol Cl−) × (1 mol FeCl2/2molCl−) × (1L /1.20molFeCl2) =0.296L
What mass of precipitate (in g) is formed when 20.5 mL of 0.400 M Mn(NO₃)₂ reacts with 23.0 mL of 0.400 M NaOH in the following chemical reaction? Mn(NO₃)₂(aq) + 2 NaOH(aq) → Mn(OH)₂(s) + 2 NaNO₃(aq)
0.409 g .The volume and molarity are provided for each reactant and the amount of moles of each can be calculated. The limiting reactant can be determined by calculating the amount of the other reactant that would be necessary for the reaction to occur. The balanced reaction provides the conversion factor. NaOH is the limiting reactant because there isn't enough of it to completely react with the amount of Mn(NO₃)₂. The amount of products can be found using conversion factors found in the balanced reaction and molar mass.
Determine the number of moles in 2.78 × 10²³ formula units of BaCl₂.
0.462 mol 2.78×1023 formula units BaCl2 × 1 mol BaCl2/6.022 × 10^23 formula units BaCl2= 0.462 mol BaCl2
What is the molarity of a solution that contains 0.185 moles KOH in 0.350 L of solution?
0.529 M 0.185 mol KOH/0.350 L =0.529M
What quantity of heat (in kJ) will be absorbed by a 30.7 g piece of aluminum (specific heat = 0.930 J/g･°C) as it changes temperature from 23.0°C to 67.0°C?
1.26 kJ .The heat can be calculated using the specific heat capacity, mass, and the change in temperature. q=mc(triangle)T Finally, the heat can be converted from J into kJ using the metric conversion factor. 1 kJ = 1000 J
How many Joules are there in 36.9 kcal? (1 cal = 4.184 J)
1.54 × 10⁵ J .Convert kcal to cal and then to J using the conversion factors. Be sure to report your answer to the appropriate significant figures, which is 3 in this case.
Determine the number of valence electrons in HCN and then draw the corresponding Lewis structure. A) 13 B) 12 C) 10 D) 9 E) 7
10
Which of the following temperatures is the coldest? A) 100 K B) 100 °C C) 100 °F
100 K Temperature in Kelvin (K) is the lowest because it is the absolute temperature. Given the same numerical value, Kelvin would always be the lowest temperature.
The chemical formula of caffeine is C₈H₁₀N₄O₂. How many N atoms are in 4 molecules of caffeine? A) 4 B) 8 C) 16 D) 32 E) 2
16
A thermometer reads -143.9 °F. What is the temperature in Kelvin?
175.4 First, the formula to convert Fahrenheit to Celsius is: °C= 5/9 (°F−32)
How many miles can you drive, if your car gets 33.70 miles per gallon and you have 12.00 gallons of gas?
404.4 miles
Determine the molar mass of Al₂(SO₄)₃･5H₂O. Provide an answer to two decimal places.
432.24 g/mol (26.98 g/mol × 2) + (32.06 g/mol × 3) + (16.00 g/mol × 17) + (1.01 g/mol × 10) =432.24 g/mol
The number 0.000741 written in scientific notation would be A) 7.41 × 10⁴ B) 7.41 × 10⁻⁴ C) 7.41 × 10³ D) 7.41 × 10⁻³
7.41 × 10⁻⁴
What is the formula of a compound containing Ba²⁺ and N³⁻ ions? A) Ba₂N₃ B) Ba₃N C) BaN₃ D) Ba₃N₂
Ba₃N₂
Which postulate(s) of Dalton's atomic theory of matter is/are NOT true? A) Atoms of a given element are identical B) Atoms are indestructible C) Atoms combine in simple ratios to form compounds D) Both (A) and (B)
Both (A) and (B) The following two hypotheses of Dalton's atomic theory are not true: ∙∙ All atoms of a given element are identical. ∙∙ Atoms are indestructible. It was later discovered that there can be atoms of the same element with different masses (isotopes). It was also later discovered that some atoms can decay by the loss of a helium nucleus, and some atoms can be split by nuclear fission.
Consider the following reaction: Mg²⁺(aq) + Cu(s) → Cu²⁺(aq) + Mg(s). In this reaction, Mg²⁺(aq) is: A) oxidized B) reduced C) a reducing agent D) an oxidizing agent E) Both (B) and (D)
Both (B) and (D) Oxidizing agents gain electrons and are reduced. Reducing agents lose electrons and are oxidized. In this reaction, Mg²⁺ gains two electrons when it becomes Mg.
When propanol (C₃H₇OH) is burned in excess oxygen, what is/are the product(s) of this reaction?
CO₂, H₂O The products of a combustion reaction are carbon dioxide and water.
Which has the incorrect name-formula combination? A) Chromium(II) sulfate - CrSO₄ B) Cobalt(III) nitrate - Co(NO₃)₂ C) Nickel(II) nitrite - Ni(NO₂)₂ D) Manganese(III) sulfite - Mn₂(SO₃)₃
Cobalt(III) nitrate - Co(NO₃)₂
A molecule has an empirical formula of CH, and its molar mass is known to be 26 g/mol. What is its molecular formula? A) CH B) CH₂ C) C₂H₂ D) C₂H E) C₃H₃
C₂H₂ An empirical formula shows the simplest ratio of each element to one another. One carbon atom and one hydrogen atom, CH, have a relative mass of 13 g/mol. If the molar mass of a molecule is 26 g/mol, this would have two carbon atoms and two hydrogen atoms, giving the formula C₂H₂.
The empirical formula of a covalent compound is CH₂. Which of the following is NOT a possible chemical formula for this compound? A) C₅H₁₀ B) C₇H₁₄ C) C₆H₁₀ D) C₄H₈ E) C₃H₆
C₆H₁₀
Terephthalic acid is a chemical used to make polyesters, including disposable water bottles. It has the empirical formula C₄H₃O₂. The molar mass of terephthalic acid is 166 g/mol. What is its chemical formula? A) C₄H₃O₂ B) C₁₂H₉O₆ C) C₈H₈O₈ D) C₈H₆O₄ E) C₁₀H₁₂O₈
C₈H₆O₄
Classify the following compounds as ionic or covalent: BaO, Fe₂O₃, ZnO. A) Covalent, covalent, covalent. B) Ionic, ionic, covalent. C) Ionic, covalent, covalent. D) Ionic, Ionic, Ionic.
Ionic, Ionic, Ionic. Ionic bonds occur between a metal and a nonmetal. Covalent bonds occur between two nonmetals.
Identify which of the following molecules has a double bond. A) O₂ B) H₂ C) Br₂ D) HF
O₂. Main group elements obey the octet rule. The Lewis structure for O₂ has a double bond with 4 valence electrons around each oxygen atom.
What is the atomic symbol for the element in Group 5A (15) and the fifth period? A) As B) Sb C) Sn D) Te E) Bi
The element that is found in the fifth row of Group 5A (15) is Sb.
What type of property is heat? A) intensive physical property B) intensive chemical property C) extensive chemical property D) extensive physical property
Unlike temperature, which measures average kinetic energy, heat measures internal energy and depends on the amount of substance present. Therefore, it is an extensive physical property.
The following picture would be best described as
a liquid compound
A sample of copper is an example of a(n) A) Element B) Compound C) Mixture
element
Draw the Lewis structure of ethyne (C₂H₂) and then choose the appropriate pair of molecular geometries of the two central atoms. Your answer choice is independent of the orientation of your drawn structure.
linear/linear
Which of the following is a step that is NOT in the scientific method? A) making observations B) formulating hypotheses C) modifying laws D) performing experiments
modifying laws
Carbon monoxide (CO) is a colorless, odorless, flammable gas that is toxic to humans above 35 ppm in air. Carbon monoxide is a(n) ______. A) molecular compound B) molecular element C) ionic compound D) monatomic element
molecular compound
Neutral atoms of all isotopes of a given element have the same A) number of protons and neutrons B) number of neutrons C) number of electrons D) mass numbers E) masses
number of electrons
The nucleus of an atom contains: A) Protons and electrons B) Protons and neutrons C) Electrons and neutrons D) Protons, neutrons and electrons E) Electrons only
protons and neutrons
Which of the following sets of elements and symbols is paired incorrectly? A) iron, Fe B) sodium, S C) tin, Sn D) potassium, K E) copper, Cu
sodium, S sodium is Na
A homogeneous mixture is also called a ____________. A) solution B) pure substance C) heterogeneous mixture D) liquid
solution
Why is the dissolving of salt in water a chemical change? A) the salt dissociates into ions B) the water gets saltier C) the water surrounds the salt compound D) the salt molecule does not dissociate into ions
the salt dissociates into ions
What is the concentration of lithium ions in 0.160 M Li₂SO₄?
0.320 M (0.320 mol Li2SO4 / 1 L) × (2 mol Li / 1 mol Li2SO4)= 0.900MLi+
Convert a pressure of 306.2 torr to atm.
0.4029 atm 1atm=760 torr
What quantity in moles of sodium atoms do you have if you have 3.80 × 10²³ atoms of sodium. (The mass of one mole of sodium is 22.99 g.)
0.631 mol 3.80 × 10^23 atoms of Na × 1 mol Na /6.022×10^23 atoms of Na=0.631 mol Na
Starting with the following equation, P₄(s) + F₂(g) → PF₃(g) calculate the moles of F₂ that will be required to produce 37.5 grams of PF₃.
0.639 mol 37.5 g PF3 x ( 1 mol PF3 / 87.97 g PF3) = 0.42628 0.42628 mol PF3 x (6 mol F2/4 mol PF3) = 0.639 mol
A 90.0 g piece of metal, initially at 98.6°C, is placed into 120.0 g of water initially at 24.3°C. If the final temperature of the water is 34.0°C, what is the specific heat of the metal? (The specific heat of water is 4.184 J/g･°C).
0.838 J/g･°C
Which of the following quantities is equivalent to 3.7 cm? A) 3.7×10⁻³ m B) 3.7×10⁻⁵ km C) 3.7×10⁻² mm D) 3.7×10⁵ μm E) 3.7×10² mm
1 centimeter is equal to 0.01 meters, 10 millimeters, 10,000 micrometers, and 1×10−51×10−5 km. Convert cm to km.
Convert a pressure of 15.95 psi to atm.
1.085 atm 1atm= 14.7 psi
A chemist has a block of lead metal (density is 11.3 g/mL). They drop the metal into a graduated cylinder containing water, and find the volume change is 1.30 mL. What is the mass of the block, in grams?
15g solution: Density is defined as the ratio of mass and volume. d=m/V We are solving for mass, so let's rearrange our formula: m=d x V Then plug in the numbers: m=11.3 g/mL × 2.30 mL m=26.0 g
How many moles of NO₂ would be produced from 2.2 mol of O₂ in the reaction below assuming the reaction has a 57.0% yield? 2 NO (g) + O₂ (g) → 2 NO₂ (g)
2.5 mol .The theoretical yield can be calculated using the mole to mole ratio and the amount of O₂. The actual yield is 57.0% of the theoretical yield, so multiply the theoretical yield by 0.57: The percent yield is equal to the actual yield divided by theoretical yield. Use the given percent yield to solve for the theoretical starting moles.
What is the mass in grams of 49.1 moles of NaCl?
2.87 × 10³ g 49.1 mol NaCl × 58.44 g NaCl/1 mol NaCl= 2.87×103 g NaCl
Starting with the following equation, Ca₃(PO₄)₂(s) + H₂SO₄(aq) → CaSO₄(s) + H₃PO₄(aq) calculate the mass in grams of Ca₃(PO₄)₂ that will be required to produce 295 grams of CaSO₄.
224 g 295 g CaSO4 x (1 mol CaSO4 / 136.14 g CaSO4) = 2.1669 2.1669 mol CaSO4 x ( 1 mol Ca3(PO4)2 / 3 mol CaSO4)= 0.7223 0.7223 mol Ca3(PO4)2 x (310.18 g Ca3(PO4)2/ 1 mol Ca3(PO4)2) = 224 g
What is the mass percentage of C in hydrochlorothiazide, C₇H₈ClN₃O₄S₂? Provide an answer to two decimal places.
28.24 % Mass percentage can be calculated by finding the ratio of the molar mass of atoms of an element to the total molar mass in a molecule or formula unit. For example, the mass percentage of C in C₇H₈ClN₃O₄S₂ is 28.24%. (12.01 g × 7) / 297.74 g × 100 = 28.24%
What is the coefficient in front of the O₂ when the equation below is balanced (using only whole numbers and the lowest whole number ratio)? C₂H₆O(g) + O₂ (g) → CO₂(g) + H₂O (g)
3
Determine the formula weight of Al₂(SO₄)₃. Provide an answer to two decimal places.
342.14 amu The formula weight is the mass of one molecule or formula unit. This can be calculated by adding the atomic mass of each atom.
If 34.0 g of NaOH is added to 0.550 L of 1.00 M Ni(NO₃)₂, how many grams of Ni(OH)₂ will be formed in the following precipitation reaction? 2 NaOH(aq) + Ni(NO₃)₂(aq) → Ni(OH)₂ (s) + 2 NaNO₃ (aq)
39.4 g .First calculate the number of moles of each reactant. For Ni(NO₃)₂, this can be calculated from the volume and molarity. For NaOH, this can be calculated using a molar mass conversion factor. The limiting reactant can be determined by calculating the amount of the other reactant that would be necessary for the reaction to occur. The balanced reaction provides the conversion factor. NaOH is the limiting reactant because there isn't enough of it to completely react with the amount of Ni(NO₃)₂. The amount of products can be found using conversion factors found in the balanced reaction and molar mass.
What is the oxidation number on the sulfur atom in SO₄²⁻?
6 Oxygen has an oxidation number of -2 when not in its elemental state or a peroxide. Multiply the number of oxygen atoms by its oxidation number. Add the oxidation numbers of all atoms together and set equal to the charge on the ion, which is -2. The oxidation number of sulfur can then be calculated. S+(4×(−2))=−2 S=+6
Determine the number of atoms in 45.0 grams of calcium, Ca. (The mass of one mole of calcium is 40.08 g.)
6.76 × 10²³ atoms . .The number of atoms of a substance can be calculated using Avogadro's number and its molar mass. For example, 61.0g Ca × 1 mol Ca/40.08gCa × 6.022×1023 atoms Ca/1 mol Ca = 9.17×10^23 atoms Ca
A 134.7 g piece of copper (specific heat 0.380 J/g･°C) is heated and then placed into 400.0 g of water initially at 20.7°C. The water increases in temperature to 22.2°C. What is the initial temperature (in °C) of the copper? (The specific heat of water is 4.184 J/g･°C).
71.2 °C
What is the mass in grams of 6.83 × 10²⁵ molecules of Cl₂?
8.04 × 10³ g 6.83×10^25 molecules Cl2 × 1 mol Cl2/6.022×10^23 molecules Cl2 × 70.91 g Cl2/1 mol Cl2= 8.04 ×10^3 g Cl2
What is the mass number for an atom of molybdenum containing 42 protons and 55 neutrons?
97 The mass number of an atom is representative of the number of protons and neutrons.
Which of the following describes a chemical change involving water? A) H₂O(l) → H₂O(s) B) H₂O(s) → H₂O(g) C) H₂O(l) → H₂(g) + ½O₂(g) D) H₂O(g) → H₂O(l)
A chemical change would involve the atoms found in a water molecule rearranging to form a new molecule or molecules with different composition(s). A physical change would involve the water molecules changing their state of matter but still remaining water molecules. H₂O(l) → H₂(g) + ½O₂(g) describes a chemical change.
Which of the following is the correct Lewis symbol for a neutral atom of Al?
A neutral atom of Al has 3 valence electrons.
The answer to the calculation below with the correct number of significant figures is 12.88(0.0034 +0.102)=
When adding or subtracting numbers, the number of significant figures is determined by the uncertainty of the number in the calculation which has the highest uncertainty. The number 0.0034 and has an uncertainty of +/- 0.0001. The number 0.102 has an uncertainty of +/- 0.001. Therefore when the addition is performed, the answer should have an uncertainty of +/- 0.001: When multiplying or dividing, the number of significant figures is determined by the number which has the least. Since 12.88 has 4 significant figures and 0.105 has 3 significant figures, the answer to this part of the calculation should have 3 significant figures. The answer to the calculation should have 3 significant figures once rounded: 1.36.
