Chemistry
What is the concentration of sodium ions in 0.295 M Na₂CO₃?
(0.295 mol Na₂CO₃/1 L) x (2 mol Na+/1 mol Na₂CO₃) = 0.590 M Na+
Convert -33.9 °C to K.
- 239.3 K *** K= -33.9 + 273.15 = 239.25
Who developed the earliest form of our modern periodic table?
Mendeleev
Which particle(s) may be found in the nucleus of an atom?
Proton and neutron
What is the correct IUPAC name for Al(NO₂)₃?
aluminum nitrite
What is the value of Avogadro's number?
- 6.022 × 10²³
What is the electron configuration of K⁺?
1s²2s²2p⁶3s²3p⁶
A state function is best described as
- A function that depends only on the starting point and ending point of a process.
Chlorine exists in nature as a mixture of two stable isotopes, Cl-35 and Cl-37. If the atomic mass of chlorine is given as 35.45 amu, which of the following represents the percent abundance of Cl-37?
23% Based on the mass numbers given for Cl-35 and Cl-37, solve the following equation for x: (35) (1−x) + (37) (x) = 35.45 35 − 35x + 37 x = 35.45 2x= 0.45 x = 0.225 0.225 x 100= 23 %
While traveling in Europe, you see a weather forecast of 25.7°C. What is this temperature in °F?
78.3 °F *** (25.7 x 9 F/5 C) + 32 F= 78.6
A 5.0 L chamber contains equal pressures of H₂ and N₂ at 25 °C. Which of these gases contains a larger number of molecules?
Both have equal numbers of moles. *** The number of moles would be the same under the same pressure, volume and temperature.
A strong electrolyte will
completely dissociate in solution
The trends in the physical properties of elements in the periodic table are _____.
descriptive *** The trends in the physical properties of elements in the periodic table are descriptive.
What is the correct IUPAC name for N₂O₄?
di nitrogen tetroxide
What is the correct IUPAC name for S₂Cl₈?
disulfur octachloride
Which group in the periodic table tends to have high electronegativity values?
the halogens *** The halogens tend to have the highest electronegativity values in the periodic table.
Effective nuclear charge, Zeff, is defined as
the true nuclear charge minus the charge that is shielded by electrons.
A sample of argon has a volume of 1.2 L at STP. If the temperature is increased to 23°C and the pressure is lowered to 0.80 atm, what will the new volume be, in L?
1.6 L P1 V1/TI = P2 V2/T2 (1 atm) (1.20 L)/(0.00 + 273.15) K = (0.800 atm) V2/ (22.0+ 273.15) K V2 = (1 atm)(1.20L) (295.15K)/ (273.15) (0.800 atm) V2 = 1.60 L
What is the mass number for an atom of xenon containing 54 protons and 78 neutrons?
132 54 + 78 = 132
Convert 2.70 atm to torr
2.70 atm x 760 torr/1 atm = 2050 torr
Balance the following chemical equation (if necessary): Ca(s) + O₂(g) → CaO(s)
2Ca(s) + O₂(g) → 2CaO(s)
Which atomic orbitals from carbon hybridize to form the bonds in CH₄?
2s, 2pₓ, 2p_y, 2p_z
Write the chemical formula for diarsenic trioxide
As₂O₃
Which of these molecules have delocalized electrons?
CO₃²⁻
Write the chemical formula for the sulfate ion
SO₄²⁻
What volume in milliliters of 0.0180 M Ca(OH)₂ is required to neutralize 75.0 mL of 0.0300 M HCl?
62.5 mL *** The balanced reaction is 2 HCl + Ca(OH)₂ → CaCl₂ + 2H₂O.
What is the mass in grams of carbon dioxide that would be required to react with 71.4 g of LiOH in the following chemical reaction? 2 LiOH(s) + CO₂(g) → Li₂CO₃(s) + H₂O(l)
65.60 g *** 71.4 g LiOH x (1 mol LiOH/23.95 g LiOH) x (1 mol CO2/2 mol LiOH) x (44.0 g CO2/ 1 mol CO2) = 65.60g
Predict the products and balance the following reaction: Ag₂SO₄(aq) + NaCl(aq) →
Ag₂SO₄(aq) + 2NaCl(aq) → Na₂SO₄(aq) + 2AgCl(s) *** AgCl is insoluble in water and will be in the form of a precipitate.
Which element has the ground state electron configuration [Ar]4s²3d¹⁰4p⁵?
Br *** This electron configuration ends with 4p, meaning it is an element in the p block (a main group element on the right-hand side of the periodic table) in the fourth row. The 5 in 4p⁵ indicates that it is the fifth element in this row, so the element must be Br.
A heated gas expands and presses on a piston. In this example, work is done:
By the gas on the piston. *** Pressure-volume work is work done by the expansion of a gas against a constant pressure, such as that provided by a moveable piston.
Which one of the following processes is exothermic?
Condensation of a gas into a liquid. *** An exothermic process releases heat. Boiling a liquid, melting a solid and converting a solid into a gas all require energy be put into the system. Gases have more energy than liquids and condensation is the change in phase from gas to liquid. This would result in the release of heat.
What element is theoretically the largest of all on the periodic table?
Francium (Fr)
Which of the following has an heat of formation equaling zero?
F₂ *** Elements that are in their natural state have an enthalpy of formation that is equal to zero. F₂ is the only element on the list that is in its natural state. The others are diatomic molecules in their natural state.
What group (G) and period (P) does the element molybdenum (Mo) belong to?
G = 6, P = 5 *** Molybdenum is found in the 6th column (Group 6) and the fifth row (Period 5) of the periodic table.
What type of light on the electromagnetic spectrum has the highest energy per photon?
Gamma waves *** Energy is directly related to frequency and inversely related to wavelength. Since gamma waves have the highest frequency and shortest wavelength, they have the highest energy.
Which of the following is an example of a covalent bond?
H - Cl *** Covalent bonds are typically formed between two nonmetals.
Which of the following bonds is a polar covalent bond?
H - Cl *** Polar bonds occur between two nonmetals and have a difference in electronegativities of the atoms.
In the following reaction, which element in what species is reduced? Zn (s) + 2 HCl (aq) → ZnCl₂ (aq) + H₂ (g)
H in HCl *** Oxidizing agents gain electrons and are reduced. H⁺ in HCl gains an electron when it becomes H₂.
Which of the following radii comparisons is correct?
In³⁺ < In⁺ *** Cations are always smaller than the neutral atom from which it is derived. Anions are always larger than the neutral atom from which it is derived. Therefore, the smaller ion in a pair will be the one with fewer electrons.
Which periodic trend quantifies the amount of energy required to remove an electron from a neutral, gaseous atom?
Ionization Energy
Which of the following atom(s) below has/have five valence electrons?
N *** elements in Group 15 have 5 valence electrons. These include: N, P, As, Sb, Bi, and Mc.
Energy of a photon is ______ proportional to frequency, and _______ proportional to wavelength.
directly, inversely
What is the shape of the 2p orbitals?
dumbbell
How many atoms of vanadium are in 1.28 grams of vanadium?
(1.28 g V) x (1 mol V/ 50.94g V) x (6.022 × 10^ 23 atoms V/ 1 mol V) = 1.51 × 10²² atoms V.
What is the mass of one mole of carbon atoms?
- 12.01 *** The mass of one mole of carbon atoms is equal to its atomic mass. The atomic mass of carbon is 12.01.
To convert from grams to number of molecules, you need to use:
- Avagadro's number - Molar mass ***To convert from grams to number of molecules, you must first convert the grams into moles, which requires the molar mass, and then you must convert the moles into number of molecules, which requires Avogadro's number.
Which of the following is a state function?
- Pressure - Volume - Temperature
How many moles of HCl are there in 75.0 mL of 0.145 M HCl?
0.0109 mol 75.0 ml x 0.145 mol/1L x 1 L/ 1000 mL = 0.0109 mol
How many calories are in 6801 J ? (1 cal = 4.18 J)
1.63 × 10³ cal *** 6801 J X 1cal/4.184 J= 1.63 × 10³ cal
How much heat will be absorbed by a 56.3 g piece of aluminum (specific heat = 0.930 J/g･°C) as it changes temperature from 23.0°C to 67.0°C?
2.30 kJ
How many grams of nitric acid, HNO₃, are required to neutralize (completely react with) 4.30 g of Ca(OH)₂ according to the acid-base reaction: 2 HNO₃(aq) + Ca(OH)₂(aq) → 2 H₂O(l) + Ca(NO₃)₂(aq)
4.30 g Ca(OH)₂ x ( 1 mol Ca(OH)₂/74.10g Ca(OH)₂) x ( 2 mol HNO₃/ 1 mol Ca(OH)₂) x (63.02 g HNO₃/1 mol HNO₃) = 7.31 g HNO₃
What is the molar mass of an unknown gas with a density of 3.30 g/L at 1.00 atm and 25.0 °C?
80.7 g/mol dRT = PM M = dRT/P = (3.30 g/L)x(0.08206 L.atm/K.mol)x(25.0 + 273.15 K)/ (1.00 atm) = 80.7 g/mol
Write the chemical formula for the ammonium ion
NH₄⁺
The nucleus of an atom contains:
Protons and neutrons
What is the atomic symbol for the element in Group 4B (4) and the fourth period?
Ti *** Ti is the element that is found in the 4th column (Group 4B) and in the 4th row (Period 4) of the periodic table.
What is the correct IUPAC name for AsBr₃?
arsenic tri bromide
Which of the following forms of radiation has the highest frequency?
gamma rays *** The electromagnetic spectrum ranges from radiation with the highest frequency (shortest wavelength) to lowest frequency (longest wavelength). Of the various types of radiation, gamma rays have the highest frequency.
Which of the following forms of radiation has the shortest wavelength?
gamma rays *** The electromagnetic spectrum ranges from radiation with the shortest wavelength (highest frequency) to longest wavelength (lowest frequency). Of the various types of radiation, gamma rays have the shortest wavelength.
What is observed when a noble gas is heated and the emitted light shone through a prism?
individual lines of varying colors *** Heating a noble gas promotes its electrons to excited energy states, which then relax to emit discrete wavelengths of light. When shone through a prism, this results in individual lines of varying colors
What is the correct IUPAC name for AgNO₂?
silver nitrite
What is the correct IUPAC name for NaHSO₄?
sodium hydrogen sulfate
Which of the following temperatures is the coldest?
- 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.
What is the difference between actual yield and theoretical yield?
- Actual yield is how much is actually produced in a reaction (it has to be given or measured), and theoretical yield is a calculation that has to be done. *** Actual yield is how much is actually produced and is given or measured in a reaction. The theoretical yield is a calculation that has to be done.
How many atm is 26.8 psi?
26.8 psi x (1 atm/14.7 psi) = 1.82 atm
If 4.1 kg of CO₂ are produced during a combustion reaction, how many molecules of CO₂ would be produced?
5.6 × 10²⁵ molecules 4.1 kg x 1000 g/ 1 kg x 1 mol/ 44.01g x 6.022 x10^23 molecules of CO2/1 mol = 5.6 × 10²⁵ molecules
What is the frequency of green light that has a wavelength of 523 nm? (c = 3.00 x 10⁸ m/s)
5.74 × 10¹⁴ s⁻¹
True or false: two electrons can simultaneously occupy the same (n,ℓ,mℓ) orbital.
True *** The Pauli exclusion principle states that no two electrons in a given atom can share the same set of four quantum numbers (n, ℓ, mℓ, ms). Two electrons may share the first three quantum numbers (n, ℓ, mℓ) as long as their ms (spin) quantum numbers are not the same, so this statement is true.
Convert 885.0 torr to atm.
1.1645 atm *** 885.0 torr x (1 atm/760 torr) = 1.1645
What volume in liters would 20.0 moles of sulfur dioxide occupy at 75.3 °C with a pressure of 3.86 atm?
148 L PV = nRT V = nRT/P (20.0 mol)x( 0.08206 L.atm/K.mol)x(75.3+273.15K)/3.86atm = 148L
Determine the mass in grams of NaCl that are in 27.5 moles of NaCl?
1607 g 27.5 moles NaCl x 58.44 NaCl/1 mol NaCl = 1607g
How many liters of fluorine gas are needed to form 559 L of sulfur hexafluoride gas if the following reaction takes place at 2.00 atm and 273.15 K: S(s) + 3F₂(g) → SF₆ (g)?
1667 L OR 1.68 × 10³ L 559 L SF₆ X 3 L F₂/ 1 L SF₆ = 1667 L
The displacement volume of an automobile engine is 167 in³. What is this volume in liters?
167 in³ x 16.4 cm³/1 in³ x 1L/1000 cm³ = 2.74 L
Write a balanced chemical equation based on the following description: the reaction of powdered aluminum and powdered iron(III) oxide produces solid aluminum oxide and liquid iron metal
2 Al(s) + Fe₂O₃(s) → Al₂O₃(s) + 2 Fe(l)
If 25.0 g of NH₃ and 32.6g of O₂ react in the following reaction, what is the mass in grams of NO that will be formed? 4 NH₃ (g) + 5 O₂ (g) → 4 NO (g) + 6 H₂O (g)
24.5 g
What is Standard Temperature and Pressure (STP)?
273.15 K and 1.00 atm
Convert 34.0 mm to inches
34.0mm x 1cm/10mm x 1in/2.54cm = 1.34in
According to the balanced reaction below, calculate the moles of NH₃ that form when 4.2 mol of N₂H₄ completely reacts: 3N₂H₄(l) → 4 NH₃(g) + N₂(g)
4.2 mol N₂H₄ x 4 mol NH₃/3 mol N₂H₄ = 5.6 mol NH₃
What volume in mL of 0.300 M NaF would be required to make a 0.0655 M solution of NaF when diluted to 250.0 mL with water?
54.6 mL M1 V1 = M2 V2
A 1.2 L weather balloon on the ground has a temperature of 25°C and is at atmospheric pressure (1.0 atm). When it rises to an elevation where the pressure is 0.78 atm, then the new volume is 1.8 L. What is the temperature (in °C) of the air at this elevation?
76 °C
Which of the following represents the generic form of a single-displacement reaction?
A + BX → AX + B *** The generic form of a single displacement reactions, also called a single replacement reaction, occurs when a single element displaces, or substitutes, another element in a compound. Single Displacement Reaction: A + BX → AX + B
Which one of the following is the correct dissociation equation for AlBr₃?
AlBr₃ (s) → Al³⁺(aq) + 3 Br⁻ (aq) *** Aluminum forms ions with a +3 charge. There are three bromine ions for every one aluminum ion. Bromine forms ions with a -1 charge.
Write the chemical formula for carbon disulfide
CS₂
Which is NOT a property of an ideal gas?
Can pass through walls *** An ideal gas consists of point particles and has no attractive or repulsive forces. It cannot pass through walls.
In which direction on the periodic table does metallic character increase?
Down and to the left.
What happens to the energy of a photon if the wavelength is doubled?
Energy is reduced by one-half
Which one of the following is the most electronegative atom?
F
Which of the following is an example of an ionic bond?
K-F *** K-F is an ionic bond because the difference in electronegativity is greater than 1.5 and it is between a metal and a nonmetal.
Which one of the following is the correct dissociation equation for Li₂CO₃?
Li₂CO₃ (s) → 2 Li⁺(aq) + CO₃²⁻ (aq) *** Lithium forms ions with a +1 charge. There are two lithium ions for every one carbonate ion. Carbonate has a -2 charge.
Which of the following ions has the electron configuration 1s²2s²2p⁶?
N³⁻
Rank the following atoms in order of increasing size (i.e., smallest to largest): Li, Al, Be, Ba, O.
O < Be < Li < Al < Ba
Write the chemical formula for tetraphosphorus hexasulfide
P₄S₆
Light wave A has a greater frequency than light wave B. Which has a greater wavelength?
Wave B *** All light travels at the same speed (c), and since speed is equal to the product of wavelength and frequency, a higher frequency results in a shorter wavelength. Because wave A has a greater frequency than wave B, wave B must have the longer wavelength.
What gas law states that volume and moles are directly proportional at constant pressure and temperature?
- Avogadro's Law *** Avogadro's Law states that at constant pressure and temperature, volume and moles are directly proportional. Mathematically this is written as: V1/n1 = V2/n2
What is the definition of a scientific law?
- It summarizes an observable behavior.
How many moles of Ag are in 70.2 grams of Ag₂O?
0.606 mol 70.2 g Ag₂O x (1 mol Ag₂O/ 231.74 g Ag₂O) x (2 mol Ag/ 1 mol Ag₂O) = 0.606 mol
Determine the number of atoms of O in 10.0 g of C₂H₆O₂.
1.94 × 10²³ atoms
Which one of the following would form a precipitate with PO₄³⁻ ions in aqueous solution?
Ca²⁺ *** Calcium phosphate is insoluble in water. Although phosphates are typically insoluble in water, exceptions are potassium phosphate and ammonium salts.
What is the mass percentage of C in morphine, C₁₇H₁₉NO₃?
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. For example, the mass percentage of C in C₁₇H₁₉NO₃ is 71.55%. (12.01g x17)/285.37g x 100 = 71.55 %
Water can dissolve ionic compounds because
water is a polar molecule.
Determine the formula weight of KBr.
- 119.00 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. The atomic mass of potassium is 39.10 amu and the atomic mass of bromine is 79.90 amu. 39.10amu+79.90amu=119.00amu
What does the mass number of an atom represent?
- total number of protons and neutrons in the atom *** The mass number of an atom represents the total number of protons and neutrons in the atom.
In a covalent bond
two atoms share valence electrons and those shared electrons form the chemical bond.
A π bond could be formed from the overlap of which two orbitals?
two unhybridized p orbitals *** Pi bonds are formed by overlapping p orbitals.
Water is a polar molecule because
water is a bent molecule and oxygen is more electronegative than hydrogen.
Water is considered the universal solvent because
water is capable of dissolving a large variety of solutes.
A more electronegative atom
will have more attraction to the electrons in a chemical bond.
Which of the following metric prefixes corresponds to 10⁻³?
- milli- *** mega- 10^6 kilo- 10^3 centi- 10^-2 milli- 10^-3 micro- 10^-6
The halogens are found in Group ____
7A (17)
A fixed container containing an ideal gas is heated. The pressure of the gas increases because
the gas molecules move faster and strike the walls of the container more often and with more force. *** Kinetic molecular theory envisions gas molecules as spheres that bounce off each other and off the walls of their container elastically. Heating the container causes the spheres to move faster, and if the container walls are fixed, the molecules will strike the wall more often and with more force, thereby increasing the pressure.
A nonelectrolyte
will not form any ions in aqueous solution.
How much money will it cost you to drive 225.0 miles if your car gets 25.70 miles per gallon and gas costs $3.309/gallon?
- $28.97 *** The following solution may contain one or more values that are different from the problem provided to you, however, the steps to solve the problem are the same. You can solve for the cost by dividing the distance driven by the gas mileage and then multiplying by the cost of one gallon of gas. 225.0 mile x 1 gal/25.70 mile x $3.309/1 gal = $ 28.97
If you have 1 mol Xe and 1 mol F₂, how many moles of XeF₄ can you create in the following chemical reaction? Xe (g) + 2 F₂ (g) → XeF₄ (g)
- 0.5 mol *** Calculate the amount of XeF₄ that could be made from the given amount of each reactant, if it were not limiting. 1 mol Xe x 1 mol XeF₄/1 mol Xe= 1 mol XeF₄ 1 mol F₂ x 1 mol XeF₄/ 2 mol F₂ = 0.5 mol XeF₄ Therefore F₂ is the limiting reactant, and 0.5 mol of XeF₄ will be produced.
How many moles are in 57.1 grams of RbF?
- 0.547 mol *** The following solution may contain one or more values that are different from the problem provided to you, however, the steps to solve the problem are the same. .Stoichiometry can be used. Since grams of RbF was provided, that will be the starting point. The molar mass provides the conversion factor. 57.0 g RbF x 1 mol RbF/ 104.47 g RbF = 0.547 mol RbF
Human blood typically contains 1.04 kg/L of platelets. A 4.27 pints of blood would contain what mass (in grams) of platelets? (1 gallon = 3.785 L, 1 gallon = 8 pints).
- 2101 g ***The following solution may contain one or more values that are different from the problem provided to you, however, the steps to solve the problem are the same. To determine the mass of platelets in grams in 1.01 pints of a blood sample, the following conversions will be helpful 1 gallon - 8 pints 1 gallon - 3.785 L 1Kg - 1000 g Using these together along with the density of platelets given as 1.04 = kg/l
How many oxygen atoms are located on the reactant side of the following chemical equation? 2 Al(s) + Fe₂O₃(s) → Al₂O₃(s) + 2 Fe(l)
- 3 *** 2 Al(s) + Fe₂O₃(s) → Al₂O₃(s) + 2 Fe(l) Oxygen can be found in iron(III) oxide, Fe₂O₃. Every molecule of Fe₂O₃ contains 2 Fe atoms and 3 oxygen atoms.
The number 3780000 written in scientific notation would be
- 3.78 × 10⁶ *** When converting a number to scientific notation, the decimal place is moved once for each power of 10 in the original number to leave only one number before the decimal point. If the original number is greater than 1, then the decimal place is moved to the left and the exponent in the ×10 indicates how many times the number needs to be multiplied by 10. 3780000= 3.78x10x10x10x10x10x10= 3.78 x 10^6
How many significant figures would this calculation have if it were completed: (9.04 - 8.23 + 21.954 + 81.0) × 3.1416
- 4 *** The result of an addition or subtraction is reported to the number of significant figures to the right of the decimal as that of the number in the calculation with the least significant figures to the right of the decimal. The result of a multiplication or division is reported with the significant figures of the number in the calculation with the least significant figures. This problem combines addition, subtraction and multiplication. Solve the problem in the order of operations and do not round until you obtain the final answer. (The limiting significant figure is underlined in the intermediate values). (9.04 - 8.23 + 21.954 + 81.0) × 3.1416 = 325.98498 326.0
Which of the following numbers contains five significant figures?
- 50.260 *** Count the number of significant figures in each option. Be sure to account for non-zero digits, zeros found between two significant digits, and zeros following a significant digit in a decimal. Leading zeros, and trailing zeros without a decimal point, are not significant. The value 50.260, contains five significant figures.
An atom of the isotope ¹³³Cs contains how many protons (p), neutrons (n), and electrons (e)?
- 55 p, 78 n, 55 e *** Isotopes are forms of the same element that differ in the number of neutrons but contain the same number of protons. The standard notation for an isotope is to indicate the mass number because its protons and electrons do not change. The symbol 133Cs133Cs indicates that the mass number is 133. Cesium has an atomic number of 55, indicating it has 55 protons, and 55 electrons in the neutral atom. The mass number of an atom is representative of the number of protons and neutrons. Calculate the number of neutrons from the mass number and the number of protons. 133= 55 + x 78= x
Which of the following represents an example of kinetic energy?
- A ball rolling down a hill. *** Kinetic energy is the energy from motion. A ball rolling down a hill is in motion. It is stationary at the top and the bottom of a hill.
If you go mini-golfing, in which of these scenarios are you precise but not accurate?
- All of your shots are off, but they all go to the same place. *** Precision is when all outcomes are in the range of uncertainty of one another and accuracy is when the average outcome is in the range of uncertainty of where it should be. Precision and accuracy are independent of one another. An outcome can be precise but not accurate, accurate but not precise, accurate and precise, or neither accurate nor precise. You are precise but not accurate in scenario D, the shots are off, but they all go to the same place.
Which postulate(s) of Dalton's atomic theory of matter is/are NOT true?
- Atoms of given element are identical - Atoms are indestructible 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.
Which one of the following processes is endothermic?
- Boiling a liquid *** An endothermic process requires heat. Freezing a solid, condensation of a gas into a liquid, and condensation of a gas into a solid all release heat. Gases have more energy than liquids. For a liquid to become a gas, energy would be need to be added to the system.
What gas law states that volume and pressure are inversely proportional at constant temperature and moles?
- Boyle's Law *** Boyle's Law states that at constant temperature and moles, pressure and volume are inversely proportional. Mathematically this is written as: P1V1=P2V2
Which one of the following processes is exothermic?
- Burning wood in a campfire. *** An exothermic process releases heat. Making coffee, baking a cake, and photosynthesis require energy. Burning wood in a campfire releases heat that can be felt radiating from the campfire.
What is the empirical formula of a compound that contains only iron and oxygen and is 22.27% oxygen?
- FeO *** To determine the molar ratio, and therefore the empirical formula, first convert the mass of each element in the compound to the number of moles of that element. This compound contains only Fe and O. If it contains 22.27% O, then 100 g of the compound contains 22.27 g of O and 100-22.27 = 77.73 g Fe. Converting to moles: 22.27 g O x 1 mol O/16 g = 1.392 mol O 77.73g Fe x 1 mol Fe/55.85g = 1.392 mol Fe 1.392 mol Fe/1.392 mol 0 = 1 mol Fe / 1 mol O So the empirical formula is FeO.
What gas law states that pressure and temperature are directly proportional at constant volume and moles?
- Gay-Lussac's Law *** Gay-Lussac's Law, also called Amonton's Law, states that at constant volume and moles, pressure and temperature are directly proportional. Mathematically this is written as: P1/T1 = P2/T2
Which one of the following statements is correct about the reaction below? Mg(s) + 2 HCl(aq) → MgCl₂(s) + H₂(g)
- H is the oxidizing agent because it gains electrons. *** Oxidizing agents gain electrons and are reduced. Reducing agents lose electrons and are oxidized. In this reaction, Mg loses two electrons to become Mg²⁺. Two H⁺ each gain one electron to become H₂.
What are the reactants in the following equation: HCl(aq) + NaHCO₃(aq)→ CO₂(g) + H₂O(l) + NaCl(aq)
- HCl, NaHCO₃ *** Reactants are found on the left side of the arrow in a chemical equation. They are HCl and NaHCO₃
What is the empirical formula of acetic acid, HC₂H₃O₂?
- H₂CO *** An empirical formula shows the simplest whole number ratio of each element to one another in the formula unit or molecule. For example, HC₂H₃O₂ contains 4 hydrogen atoms, 2 carbon atoms, and 2 oxygen atoms. This can be reduced to 2 hydrogen atoms, 1 carbon atom, and 1 oxygen atom.
Which one of the following would be a chemical property of a sample of neon gas?
- It is inert. *** If a property (being inert) can not be measured without chemically changing the substance, it's a chemical property.
Under what conditions are gases most likely to behave ideally?
- Low pressures *** Gases are more likely to behave as ideal gases at low pressures and high temperatures. Particles are moving faster and are farther apart, therefore they are less likely to interact with each other.
The ions formed when MgI₂ dissociates in water are
- Mg²⁺ and I⁻ *** MgI₂ dissociates into Mg²⁺ and I⁻. The charges on the atoms can be determined by the number of electrons in their valence shells. Magnesium, Mg, is in Group 2 and loses 2 valence electrons to have a +2 charge. Iodine, I, is in Group 17 and has 7 valence electrons. Iodine will gain an electron to have take on a -1 charge.
What is the element symbol for manganese?
- Mn *** The Periodic Table provides element names and symbols. The element symbol for manganese is Mn.
Which has a greater mass?
- Proton *** A proton has a mass of 1.673 × 10^ −27kg, an electron has a mass of 9.109×10^ −31 kg, and a neutron has a mass of 1.675×10^−27 kg.
Of the following compounds, which contains a metalloid?
- SiF₄ *** Metalloids are elements that have properties of both metals and nonmetals. The metalloids are: B, Si, Ge, As, Sb, Te and Po.
Which is not one of Dalton's hypotheses of atomic theory?
- The atoms of one element are the same as atoms of another element. *** Dalton's atomic theory contains the following hypotheses: ∙∙ Elements are composed of atoms. ∙∙ Compounds are composed of atoms of more than one element. ∙∙ A chemical reaction involves the rearrangement of atoms. ∙∙ All atoms of a given element are identical. ∙∙ Atoms are indestructible. The statement that "atoms of one element are the same as atoms of another element" is not only not one of his hypotheses, the statement is inCorrect!
Which of the following has the greatest amount of potential energy?
- a ball at the top of a hill. *** Potential energy is the energy that an object possesses when not in movement. Potential energy is higher for objects that are higher off the ground. Therefore the ball at the top of the hill would have the greatest amount of potential energy.
How would you determine the formula weight of NaCl?
- add the mass of sodium (22.99 amu) plus the mass of chlorine together (35.45 amu). *** Formula weight is calculated by adding the atomic masses of each atom in the formula unit.
For which set of conditions would Xe behave most like an ideal gas?
- at 1 atm and 800 K *** Xe is likely to behave like an ideal gas at high temperatures and low pressures. The particles would be moving faster and they would be further apart, and would therefore be less likely to react.
Fill in the blank: A mole equals any element's ___________.
- atomic weight *** A molar mass value is equivalent any element's atomic weight.
What type of reaction is represented by the following equation: 2Na(s) + Cl₂(g) → 2NaCl(s)
- combination *** This is a combination reaction, involves two compounds reacting to form one new compound. This type of reaction is also known as a synthesis reaction.
Which one of the following is NOT an example of a compound?
- concrete *** A compound has two or more elements chemically bound together and cannot be separated by physical means.
Which of the following are physical properties of matter?
- density *** If a property (density) can be measured without changing the substance, it's a physical property.
Density is defined as mass _____________ volume.
- divided by *** Density is an intensive property of a substance and is defined as density=mass/volume.
Which of the following are chemical properties of matter?
- flammability *** If a property (flammability) can not be measured without changing the substance, it's a chemical property.
Italian dressing contains olive oil and vinegar, which will separate out from each other if left to sit. This makes the dressing a:
- heterogeneous mixture *** Italian dressing is a heterogeneous mixture that has a difference in composition within the mixture.
Which of the following is a step that is NOT in the scientific method?
- modifying laws *** The scientific method involves making observations, formulating hypotheses, performing experiments and revising or making new hypotheses to be tested.
Rutherford's gold foil experiment determined that
- most of the space in an atom is empty except for a concentrated area called the nucleus. *** Ernest Rutherford's gold foil experiment determined that most of the space in an atom is empty except for a concentrated area called the nucleus.
What type of reaction is represented by the following equation: C₄H₈(g) + 6O₂(g) → 4CO₂(g) + 4H₂O(g)
- redox (oxidation-reduction) *** This is a redox equation, which involves the oxidation (loss of electrons) and reduction (gain of electrons) between species in the reaction.
When molecules absorb heat, there is an increase in
- the kinetic energy of the molecules. *** When molecules absorb heat, there is an increase in the kinetic energy of the molecules because the molecules move faster.
An unknown solid is added to water in a calorimeter. The temperature of the water increases. What does this say about the reaction?
- the reaction is exothermic - the reaction has released heat to the solution. ***If the temperature of the water increased, this indicates that an exothermic reaction occurred and that the heat was released to the solution.
An exothermic reaction causes the surroundings to
- warm up *** An exothermic reaction transfers energy from the system to the surroundings. That tells us the surroundings will get warmer.
Which of the following pairs represent isotopes?
- ²⁸Si and ²⁹Si *** Isotopes are forms of the same element that differ in the number of neutrons but contain the same number of protons. The standard notation for an isotope is to indicate the mass number because its protons and electrons do not change.
Which of the following would be an isotope of ¹⁴N?
- ¹⁶N *** Isotopes are forms of the same element that differ in the number of neutrons but contain the same number of protons and electrons. ¹⁶N is an isotope of ¹⁴N.
Using the provided table, determine the enthalpy for the reaction C₃H₈ (g) + 5 O₂ (g) → 3 CO₂ (g) + 4 H₂O (g)
-2039 kJ/mol *** 3 x (-393.5 kJ/mol) + 4 x (-241.8 kJ/mol) - (108.4 kJ/mol) - 5 x (0 kJ/mol) = -2039.3 kJ/mol
How many moles of KClO₃ must be reacted according to the following balanced chemical reaction to transfer -34.2 kJ of heat? 2 KClO₃(s) → 2 KCl(s) + 3 O₂(g) ∆H = -89.4 kJ
-34.2 kJ x 2 mol KClO₃/-89.4 kJ = 0.765 mol KClO₃
Determine the mass in grams of 4.31 × 10²¹ atoms of arsenic. (The mass of one mole of arsenic is 74.92 g.)
0.536 g The following solution may contain one or more values that are different from the problem provided to you, however, the steps to solve the problem are the same. .The number of moles of a substance can be calculated using Avogadro's number. Then, the mass can be calculated using the molar mass.For example, 4.31 × 10²¹ atoms of As x ( 1 mol As/ 6.022 x 10^23 atoms of As) x (72. 93 g As/ 1 mol As) = 0.536 g
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 4.18 J/g･°C).
0.837 J/g･°C
In sp²-hybridized orbitals, how many p-orbitals remain to form multiple bonds?
1 *** There are three p-orbitals and one s-orbital in each energy level, but an sp²-hybridized orbital uses more than one of the p-orbitals. This means that sp² hybridization leaves one p orbital free to pi bond.
How many moles of C are formed upon complete reaction of 2 mol of B according to the generic chemical reaction: A + 2B → C
1 mol C
What is the mass in grams of precipitate formed when 45.5 mL of 0.300 M Na₃PO₄ reacts with 35.0 mL of 0.200 M Cr(NO₃)₃ in the following chemical reaction? Na₃PO₄ (aq) + Cr(NO₃)₃ (aq) → CrPO₄ (s) + 3 NaNO₃ (aq)
1.03 g
A balloon is filled to a volume of 1.50 L with 3.00 moles of gas at 25 °C. With pressure and temperature held constant, what will be the volume (in L) of the balloon if 0.20 moles of gas are added?
1.60 L V1/n1 = V2/n2 150 L/ 3.00mol = x/ (3.00 mol + 0.20 mol) x = (1.50 L)x(3.20 mol)/ (3.00 mol) = 1.60 L
How much heat is absorbed in the process of making 0.861 mol of CF₄ from the following reaction? C (s) + 2 F₂ (g) → CF₄ (g) ∆H° = 141.3 kJ/mol
122 kJ 0.861 mol CF₄ x 141.3 kJ/1 mol CF₄ = 122 kJ
Aluminium has a density of 2.70 g/cm³. How many moles of aluminum are in a 13.2 cm³ block of the metal substance?
13.2 cm^ 3 × (2.70 g Al/ 1 cm^3) × 1 mol Al/26.98 g Al = 1.32 mol Al
Which of the following is the electron configuration of a neutral K atom?
1s²2s²2p⁶3s²3p⁶4s¹ *** The element K is in the first column of the periodic table (meaning it is in the s block) and the fourth row, so its electron configuration will end with 4s¹. The electron configuration of K is 1s²2s²2p⁶3s²3p⁶4s¹.
Balance the following chemical equation (if necessary): Fe(NO₃)₃(aq) + Sn(s) → Fe(s) + Sn(NO₃)₂(aq)
2 Fe(NO₃)₃(aq) + 3 Sn(s) → 2 Fe(s) + 3 Sn(NO₃)₂(aq)
If 33.0 g of CH₃OH (MM = 32.04 g/mol) are dissolved in 500.0 mL of solution, what is the concentration of CH₃OH in the resulting solution? (Assume the volume does not change after the addition of the solid.)
2.06 M (33g/500ml) x (1 mol/32.04g) x (1000ml/1 l) =2.06M
How many grams of oxygen gas are produced when 2.43 × 10⁻⁴ g of KClO₃ are completely reacted according to the following chemical equation: 2KClO₃(s) → 2 KCl(s) + 3 O₂(g)
2.43 x 10^-4 g KCIO3 X (1 mol KCIO3/122.55 g KCIO3) x (3 mol O2/2 mol KCIO3) x (32 g O2/1 mol O2) = 9.52 x 10 ^ -5 g O2
What is the energy of a mole of photons that have a wavelength of 439 nm? (h = 6.626 × 10⁻³⁴ J • s and c = 3.00 × 10⁸ m/s)
2.72 × 10⁵ J
Determine the number of atoms in 30.0 g of K.
4.62 × 10²³ atoms 30 g K x (1 mol K/39.10 g K) x (6.022 x 10^23 atom K/1 mol K) = 4.62 x 10^23 atoms K
Using the equations 2 C₆H₆ (l) + 15 O₂ (g) → 12 CO₂ (g) + 6 H₂O (g)∆H° = -6271 kJ/mol 2 H₂ (g) + O₂ (g) → 2 H₂O (g) ∆H° = -483.6 kJ/mol C (s) + O₂ (g) → CO₂ (g) ∆H° = -393.5 kJ/mol Determine the enthalpy for the reaction 6 C (s) + 3 H₂ (g) → C₆H₆ (l).
49 kJ/mol
The oxidation number on the phosphorus in Na₃PO₄ is
5 *** Oxygen has an oxidation number of -2 when not in its elemental state. Multiply the number of oxygen atoms by its oxidation number. Sodium has an oxidation number of +1 when not in its elemental state. Multiply the number of sodium atoms 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 phosphorus can then be calculated. P + (4 x (-2)) + (3 x (+1)) = 0 P= +5
What is the mass percentage of O in CO₂?
72.71 % *** The following solution may contain one or more values that are different from the problem provided to you, however, the steps to solve the problem are the same. .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. For example, the mass percentage of O in CO₂ is 72.71%. (16.00g x2)/ 44.01g x 100 = 72.71 %
Using the equations 2 Sr(s) + O₂ (g) → 2 SrO (s) ∆H° = -1184 kJ/mol CO₂ (g) → C (s) + O₂ (g) ∆H° = 394 kJ/mol Determine the enthalpy for the reaction C(s) + 2 SrO(s) → CO₂ (g) + 2 Sr(s).
790 kJ/mol
One of the commercial uses of sulfuric acid is in the production of calcium sulfate and phosphoric acid. If 25.4 g of Ca₃(PO₄)₂ reacts with an excess of H₂SO₄, what is the percent yield if 13.4 g of H₃PO₄ are formed in the following UNBALANCED chemical equation? Ca₃(PO₄)₂ (s) + H₂SO₄ (aq) → H₃PO₄ (aq) + CaSO₄ (aq)
83.5 %
In which one of the following processes is the system endothermic?
A process taking place in solution where the solution temperature decreases. *** An endothermic process requires heat. The solution temperature decreases because the solvent is part of the surroundings and the chemical system is pulling heat from the surroundings.
An 80.0 g sample of metal, initially at 96.0°C, is placed into 150. g of water initially at 26.0°C in a calorimeter. The final temperature of the water is 28.1°C. What is the identity of the metal? (The specific heat of water is 4.18 J/g･°C.)
Ag
What is the molecular formula of a compound with an empirical formula of CH and a molar mass of 78.1 g/mol?
An empirical formula shows the simplest whole number ratio of each element to one another in the formula unit or molecule. The molar mass of CH is 13.02 g. Divide the molar mass of the unknown compound by the molar mass of the empirical formula to find the total number of CH units in the molecular formula. 78.1g /13.02g = 6 Multiply the empirical formula by this value to get C₆H₆.
Which of the following is not a property affected by the effective nuclear charge, Zeff?
Color
Which has the incorrect name-formula combination?
Copper(I) sulfide - CuS *** Consider the charge of the ions to make sure the charges are balanced. For the transition metals, the charge is indicated in the name with a Roman numeral in parentheses. For example, copper(I) sulfide indicates that the copper ion has a +1 charge. Sulfide has a -2 charge. The formula for copper(I) sulfide would be Cu₂S.
Which element has the electron configuration 1s²2s²2p⁶3s²3p⁶4s¹3d⁵?
Cr
Write the chemical formula for cesium carbonate
Cs₂CO₃
Write the chemical formula for the acetate ion
C₂H₃O₂⁻
Balance the following chemical equation (if necessary): C₅H₁₀O(l) + O₂(g) → H₂O(g) + CO₂(g)
C₅H₁₀O(l) + 7 O₂(g) → 5 H₂O(g) + 5 CO₂(g)
Which scientist developed the nuclear model of the atom?
Ernest Rutherford
Columns on the periodic table are known as
Groups
Which of the following is not an example of a covalent bond?
Mg - N *** Typically a nonmetal bonded to a nonmetal is a covalent bond.
Which one of the following can be classified as a strong electrolyte?
NH₄NO₃ *** NH₄NO₃ dissolves in water and completely dissociates into ammonium ions and nitrate ions. Therefore it is classified as a strong electrolyte.
Which one of the following would form a precipitate when mixed with aqueous Ba(NO₃)₂?
Na₂SO₄ *** When sodium sulfate, Na₂SO₄, is mixed with barium nitrate, Ba(NO₃)₂, in aqueous solution the precipitate barium sulfate, BaSO₄, is formed. Although sulfates are typically soluble in water, BaSO₄ is an exception and therefore insoluble in water. Ba(NO₃)₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaNO₃(aq)
Which one of the following will dissociate into the largest number of ions in solution?
Na₃PO₄ *** Na₃PO₄ will dissociate into the largest number of ions in solution. Sodium forms ions with a +1 charge. There are three sodium ions for every one phosphate ion. This dissociates into four ions.
Valence electrons in which of the following atoms experience the greatest effective nuclear charge (Zeff)?
Ne *** The Zeff increases from left to right in the periodic table.
What is the correct formula for nickel(II) hypobromite?
Ni(BrO)₂ *** The (II) in nickel(II) hypobromite indicates that the nickel ion has a +2 charge. Hypobromite is a polyatomic ion that has a -1 charge. Two hypobromite ions would be needed to balance the charge on the nickel ion.
You have a two-liter sample of each of the following gases, all at 25 °C and one atmosphere pressure. Which sample will weigh the most?
Nitrogen dioxide *** Nitrogen dioxide has a molar mass of 46.01 g, carbon dioxide has a molar mass of 44.01 g, argon has a molar mass of 39.95 g and ammonia has a molar mass of 17.04 g. The nitrogen dioxide sample would weigh the most with the same number of moles.
Which of the following series of isoelectronic ions (Mg²⁺, N³⁻, F⁻, Si⁴⁺) has the ionic radii in order of largest to smallest?
N³⁻ > F⁻ > Mg²⁺ > Si⁴⁺ *** For isoelectronic species, anions will be larger than cations. Ions can be further ranked by considering their charges. The greater the negative charge, the larger the size. The greater the positive charge, the smaller the size.
Which of the following states that no two electrons can have the same set of four quantum numbers?
Pauli exclusion principle *** The Pauli exclusion principle states that no two electrons in a given atom can share the same set of four quantum numbers (n, ℓ, mℓ, ms).
Complete the balanced molecular chemical equation for the reaction below. If no reaction occurs, write NR after the reaction arrow.
Pb(NO₃)₂(aq) + 2 KI(aq) → PbI₂(s) + 2 KNO₃(aq)
Similar properties recur periodically when elements are arranged according to increasing atomic number is the statement of the ______.
Periodic Law *** The Periodic Law states that similar properties recur periodically when elements are arranged according to increasing atomic number.
What type of light on the electromagnetic spectrum has the lowest energy per photon?
Radio waves *** Energy is directly related to frequency and inversely related to wavelength. Since radio waves have the lowest frequency and longest wavelength, they have the lowest energy.
Which of the following bonds is the most polar?
Rb - Br *** Elements that are located far away from each other on the periodic table have larger electronegativity differences and therefore make more polar bonds. Of all the element pairs listed, Rb and Br are the farthest apart.
Rank the following atoms in order of increasing first ionization energies (i.e., lowest to highest): Rb, F, Mg, B, N.
Rb < Mg < B < N < F
Which scientist determined the charge of the electron?
Robert Millikan *** Robert Millikan determined the charge of the electron in 1909 during his oil drop experiment.
Which of the following electron configurations is incorrect?
S [Ne]3s³3p⁴ *** The s block of the periodic table represents the first two columns, indicating that s orbitals are only capable of holding 2 electrons. Therefore, the electron configuration for S cannot be [Ne]3s³3p⁴, which has 3 electrons in the 3s orbital.
Which element has the ground state electron configuration [Kr]5s²4d¹⁰5p³?
Sb *** This electron configuration ends with 5p, meaning it is an element in the p block (a main group element on the right-hand side of the periodic table) in the fifth row. The 3 in 5p³ indicates that it is the third element in this row, so the element must be Sb.
Which of the following is NOT an alkali or alkaline earth element?
Sc *** The alkali metals are found in Group 1 (column 1) and the alkaline earth metals are found in Group 2 (column 2). Sc is found in Group 3 (column 3).
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.
An unknown element X has the following isotopes: ²⁵X (80.5% abundant) and ²⁷X (19.5% abundant). What is the average atomic mass in amu of X?
The atomic mass is an average that represents the abundance of each isotope. It can be calculated by multiplying each atomic mass by its abundance in decimal form and adding them together. (0.805 × 25) + (0.195 × 27) = 25.4 amu
According to the Kinetic Molecular Theory
The average kinetic energy is proportional to the temperature of the system. The Kinetic Molecular Theory states: ⋅⋅There is no attraction between the gas particles. ⋅⋅The volume available to the gas particles is equal to the volume of the container. ⋅⋅The measured pressure is from collisions of the gas particles with the walls of the container. ⋅⋅The average kinetic energy is proportional to the temperature of the system. Therefore, the statement "The average kinetic energy is proportional to the temperature of the system." is the correct answer.
If a sealed, rigid container's pressure is doubled, what will happen to temperature?
The temperature will increase by a factor of 2 *** Gay-Lussac's Law, also called Amonton's Law, states that at constant moles and volume, the temperature and pressure are directly proportional, so temperature must double.
When water cools from 10 °C and then freezes to become ice, which of the following best describes describe the heat flow between the system and surroundings?
The water is releasing energy as its temperature decreases, and that energy is absorbed by the surroundings.
A helium balloon initially at room temperature is dunked into a bucket of liquid nitrogen (T = 77 K). Which of the following will occur?
Volume decreases *** The balloon is a closed system and the number of moles will remain constant. The volume will change and will decrease because there is an direct relationship between temperature and volume.
Which of the following is the electron configuration for Ba?
[Xe]6s² *** The element Ba is in the second column of the periodic table (meaning it is in the s block) and the sixth row, so its electron configuration will end with 6s. The last noble gas filled prior to Ba is Xe, so the electron configuration of Ba is [Xe]6s².
What is the correct IUPAC name for BrCl₃?
bromine tri chloride
What is the correct IUPAC name for CoCl₂
cobalt(II) chloride
What type of reaction is represented by the following equation: BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq)
double displacement *** This is a double displacement reaction, which involves two ionic compounds that react and form two new ionic compounds. The cations from the reactants "switch" places.
Elements that are most similar in their properties are found _____
in the same group.
Red light has a _____ frequency and a _____ wavelength than ultraviolet rays.
lower, longer *** As can be seen on the electromagnetic spectrum, red light (and all visible light) has a lower frequency, and therefore a longer wavelength, than ultraviolet rays.
Which of the following sets of quantum numbers is not allowed?
n = 2, ℓ = 2, mℓ = 2 *** According to the rules governing acceptable quantum numbers, the value for ℓ can only be as high as n-1, so the value of ℓ cannot equal the value of n. Therefore, the set {n = 2, ℓ = 2, mℓ = 2} is not allowed.
The First Law of Thermodynamics tells us
that the energy of the universe is a constant.
What is the correct IUPAC name for Sn(ClO)₄?
tin(IV) hypochlorite
What is the atomic symbol and mass number for an atom containing 50 protons and 64 neutrons?
¹¹⁴Sn isotopes are forms of the same element that differ in the number of neutrons but contain the same number of protons. The standard notation for an isotope is to indicate the mass number because its protons and electrons do not change. The mass number of an atom is representative of the number of protons and neutrons. x=50+64 x=114 Consult the periodic table to find the element that contains 50 protons and this yields the atomic symbol 114Sn114Sn.
Given a particular value of the principal quantum number (n), which quantum number primarily determines the shape of an orbital?
ℓ *** The shape of an orbital is determined by the number of angular nodes in that orbital, which is given by the quantum number ℓ.
If a reaction is exothermic, what is true of its reverse reaction?
∆H > 0 *** The reverse reaction would be endothermic, which would have a positive ∆H.
