Chem Chemical Reactions
Given the balanced chemical equation: 2 H2(g) + O2(g) → 2 H2O(g), two molecules of hydrogen react with _____ molecule(s) of oxygen to generate _____ molecule(s) of water
1 2
Which conversion factor can be generated from the balanced chemical reaction below? CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(g) 1 mol CO2 / 1 mol O2 1 mol CH4 / 1 mol H2O 2 mol CH4 / 2 mol H2O 1 mol CO2 / 1 mol H2O
1 mol CO2 / 2 mol H2O
Given the balanced chemical reaction 2 HCl(aq) + Na2CO3(aq) → 2 NaCl(aq) + H2O(l) + CO2(g) rank the the following reactants in order of an increasing amount of NaCl that the reactant can generate: (List the largest quantity at the bottom.) 1 mol HCl 3 mol HCl 1 mol Na2CO3 4 mol Na2CO3
1 mol HCl 1 mol Na2CO4 3 mol HCl 4 mol Na2CO3
Given the balanced chemical reaction 2 HCl(aq) + Na2CO3(aq) → 2 NaCl(aq) + H2O(l) + CO2(g) which of the following conversions can be generated? (Select all of the correct conversion factors.) 1 mol HCl / 2 mol NaCl 1 mol Na2CO3 / 2 mol NaCl 1 mol CO2 / 2 mol HCl 2 mol Na2 CO3 / 1 mol H2O
1 mol Na2CO3 / 2 mol NaCl 1 mol CO2 / 2 mol HCl
Correctly order the steps necessary to solve for the mass of a product, or second reactant required, given the mass of one of the reactants in a chemical process. Start with the first step at the top of the list. Convert the moles of the second substance to mass using its molar mass. Write a balanced equation for the reaction. Convert the given mass into moles using molar mass. Convert moles of A to moles of B using a conversion factor derived from the balanced equation.
1. Write a balanced equation for the reaction. 2. Convert the given mass into moles using molar mass. Convert moles of A to moles of B using a conversion factor derived from the balanced equation. 3. Convert the moles of the second substance to mass using its molar mass.
Correctly order the steps necessary to balance a chemical equation. Balance the atoms of each element in turn, by adding coefficients before the chemical formulas of reactants and products. Adjust the coefficients such that the smallest whole-number coefficients are used. Do a final check to make sure the equation is balanced. Write a skeleton equation
1. Write a skeleton equation 2. Balance the atoms of each element in turn, by adding coefficients before the chemical formulas of reactants and products. 3. Adjust the coefficients such that the smallest whole-number coefficients are used. 4. Do a final check to make sure the equation is balanced.
How many grams of calcium chloride are generated when 5.19 grams of calcium react in the the reaction below? 14.4 g CaCl2 5.19 g CaCl2 9.78 g CaCl2 1.87 g CaCl2
14.4 g CaCl2
Which of the following is a redox reaction? HF (aq) + NaOH (aq) → H2O (l) + NaF (aq) AgNO3 (aq) + NaCl (aq) → AgCl (s) + NaNO3 (aq) 2 SO2 (g) + O2 (g) → 2 SO3 (g)
2 SO2 (g) + O2 (g) → 2 SO3 (g)
Which of the following provides the correct mathematical operation to calculate the number of molecules in 2.0 mol of CH4? 2.0 mol / 6.022 × 10^23 molecules/mol 2.0 mol x 6.022 x 10^23 molecules/mol 6.022 x 10^23 molecules / mol / 2.0 mol 1 / 2.0 mol x 6.022 x 10^23 molecules
2.0 mol × 6.022 × 10^23 molecules/mol
Calculate the formula weight of Mg3(PO4)2. 198.860 amu 262.858 amu 214.248 amu 167.886 amu
262.858 amu
Calculate the formula weight of Mg3(PO4)2. 262.858 amu 198.860 amu 214.248 amu 167.886 amu
262.858 amu
Calculate the formula weight of Cs2S. 164.971 amu 297.877 amu 329.943 amu 108.209 amu
297.877 amu 2(132.90545) + 32.065 = 265.8109 + 32.065
Given a balanced chemical equation, determine the number of conversion factors needed to determine grams of product from grams of reactant. 1 2 3 4
3 Reason: The conversion factors are the molar mass of the reactant, the mole to mole conversion factor, and the molar mass of the product.
Calculate the correct number of moles AND formula units in 7.3 x 10^-3 g of CaSO4. Avogadro's number is 6.022 x 10^23. 9.9 x 10^-1 moles of CaSO4 8.9 x 10^-29 formula units of CaSO4 3.2 x 10^19 formula units of CaSO4 5.4 x 10^-5 moles of CaSO4
3.2 x 10^19 formula units of CaSO4 5.4 x 10^-5 moles of CaSO4
The synthesis of tamoxifen requires five steps. What is the overall percent yield if the percent yield of the synthesis steps are 85%, 95%, 85%, 84%, and 61%, respectively? .35% 61% 35%
35%
Which conversion factor correct correctly describes a mass/mole/molecule relationship for HCl? 6.02x10^23 g HCl / 36.46 molecules HCl 36.46 g HCl / 6.02 x 10^23 molecules HCl 36.46 g HCl / 6.02x10^23 mol HCl
36.46 g HCl / 6.02 x 10^23 molecules HCl
In balancing the following chemical equation, what coefficient should be placed in front of H2O? H3PO4 + Ca(OH)2 → Ca3(PO4)2 + H2O 12 1 6 3
6
The number of entities in a mole (to 3 significant figures) is equal to _____ x 10^23 and is called _____ number (form and spelling matters).
6.02 avogadro's
Which of the following correctly reflects Avogadro's number? 6.022 × 10^23 entities x 1 mol 6.022×10^23 entities / 1 amu 6.022×10^23 entities / 1 mol 6.022×1023 entities / 1 g
6.022 x 10^23 entities / 1 mol
The synthesis of ibuprofen, an anti-inflammatory drug, requires three steps. What is the overall percent yield if the percent yield of the individual synthetic steps are 75%, 90%, and 96%, respectively? 0.65% 65% 75%
65% 75% x 90% x 96% = .648
How many grams of KMnO4 correspond to 3.13 x 10^22 formula units of KMnO4? Avogadro's number is 6.022 x 10^23. 3.29 x 10^-4 g KMnO4 8.21 g of KMnO4 0.0520 g of KMnO4 158 g of KMnO4
8.21 g of KMnO4
What is the percent yield when 14.1 g of oxygen, O2, reacts with methanol, CH4O, to form 10.6 g carbon dioxide, CO2? 2 CH4O(l) + 3 O2(g) → 2 CO2(g) + 4 H2O(g) 0.820% 82% 75.2% 54.7%
82%
What is the percent yield when 14.1 g of oxygen, O2, reacts with methanol, CH4O, to form 10.6 g carbon dioxide, CO2? 2 CH4O(l) + 3 O2(g) → 2 CO2(g) + 4 H2O(g) 0.820% 54.7% 82.0% 75.2%
82.0%
What is the percent yield when 34.5 g of methanol, CH4O, reacts with oxygen to form 35.3 g water? 2 CH4O(l) + 3 O2(g) → 2 CO2(g) + 4 H2O(g) 91.0% 0.910% 55.0% 97.7%
91 %
What is the percent yield when 34.5 g of methanol, CH4O, reacts with oxygen to form 35.3 g water? 2 CH4O(l) + 3 O2(g) → 2 CO2(g) + 4 H2O(g) 0.910% 55.0% 91.0% 97.7%
91.0%
Which statement is correct about the ratio of reactants to products in a chemical equation? An unbalanced chemical equation tells us the ratio of the moles of reactants used and products formed. A balanced chemical equation tells us the ratio of the masses of reactants used and products formed. A balanced chemical equation tells us the ratio of the moles of reactants used and products formed. A balanced chemical equation tells us only the ratio of the moles of reactants used.
A balanced chemical equation tells us the ratio of the moles of reactants used and products formed.
A reaction vessel contains reactants A and B in a mole ratio of 1:1. If A and B react according to the balanced equation below, which reactant is in excess? 2 A + 3 B → A2B3 Not enough information is given to determine the answer. A is the excess reactant. The reactants are in the correct ratio so that there is no excess reactant. B is the excess reactant.
A is the excess reactant. Reason: Calculate the moles of product formed when 2 moles of A reacts and when 1 mole of B reacts
Which of the following statements correctly describe oxidizing agents and reducing agents? An oxidizing agent gains electrons. A reducing agent causes an element to be oxidized. A reducing agent gains electrons. An oxidizing agent is reduced. Every redox reaction has a reducing agent and an oxidizing agent.
An oxidizing agent gains electrons. An oxidizing agent is reduced. Every redox reaction has a reducing agent and an oxidizing agent
Which of the following should you do when balancing a chemical equation? Balance the equation with coefficients one element at a time. Change subscripts in chemical formulas to balance the equation when necessary. Move a substance from one side of the chemical equation to the other when necessary. Check your solution to verify that the same number of each type of atom is present on both sides of the reaction.
Balance the equation with coefficients one element at a time. Check your solution to verify that the same number of each type of atom is present on both sides of the reaction.
60.0 g of Br2 and 30.0 g of C6H6 are combined and allowed to react according to the reaction shown. Select the option that correctly identifies the limiting reactant and the quantity of C6H4Br2 that can be produced. C6H6 + 2 Br2 → C6H4Br2 + 2 HBr Br2 and C6H6 are present in a ratio that will cause them both to be completely consumed. 0.188 mol of C6H4Br2 can be produced. C6H6 is the limiting reactant, and 0.384 mol of C6H4Br2 can be produced. Br2 is the limiting reactant, and 0.188 mol of C6H4Br2 can be produced.
Br2 is the limiting reactant, and 0.188 mol of C6H4Br2 can be produced.
Identify the species that are oxidized and reduced in the reaction below. CH4O + O2 → CO2 + H2O CO2 is oxidized and H2O is reduced. O2 is oxidized and CH4O is reduced. CH4O is oxidized and CO2 is reduced. CH4O is oxidized and O2 is reduced.
CH4O is oxidized and O2 is reduced.
Which of the following steps would be required to convert between the masses of any two substances involved in the same chemical reaction? Calculate the molar masses of all substances in the reaction. Convert from the given mass to moles of the same substance. Write a conversion factor using the coefficients from the balanced equation, and convert to moles of the second substance. Use the coefficients from the balanced equation to convert directly from the mass of one substance to the other. Write a balanced chemical equation for the reaction.
Convert from the given mass to moles of the same substance. Write a conversion factor using the coefficients from the balanced equation, and convert to moles of the second substance. Write a balanced chemical equation for the reaction.
True or false: In order to balance the reaction of hydrogen gas (H2) with oxygen gas (O2) to form liquid H2O, a student adds a subscript of 2 to H2O (forming H2O2). This is an acceptable method of balancing the reaction described.
False Reason: Formulas of species involved in chemical reactions should never be changed, because this changes the identity of the compound. Only coefficients should be added to balance chemical equations.
Which of the following are redox reactions? Fe2+ + Mg → Fe + Mg2+ charcoal burning Precipitation of AgCl (s) from the reaction of sodium chloride and silver nitrate. iron rusting
Fe2+ + Mg → Fe + Mg2+ charcoal burning iron rusting
Which of the following substances are the products in this chemical reaction? Select all that apply. CH3CH2OH + 3 O2 → 2 CO2 + 3 H2O H2O CO2 CH3CH2OH O2
H2O CO2
Which of the following compounds has the largest molar mass? C6H6 CH2Cl2 H2SO4 SO2
H2SO4
Using the balanced equation, 2 HCl(aq) + Ca(s) → CaCl2(aq) + H2(g), determine the limiting reactant when 35.6 g of calcium are combined with 52.3 g of hydrochloric acid, HCl. HCl Ca neither, the reactants are in the correct ratio to completely react
HCl
A pacemaker is powered by a lithium battery, which generates an electrical current using the oxidation-reduction reaction shown. Match the terms to correctly describe the fates of the two reactants in the battery. 2 Li + I2 →2 LiI Li - I2 - is oxidized in the reaction is reduced in the reaction
Li - is oxidized in the reaction I2 - is reduced in the reaction.
In the following reaction, which is commonly found in alkaline batteries, Zn + 2 MnO2 + 2 H2O → Zn(OH)2 + 2 MnO(OH), the formula of the oxidizing agent is _____ and the formula of the reducing agent is _____
MnO2 or Mn02 Zn or zinc
Which of the following actions are permitted in balancing a chemical equation? Multiplying all coefficients by a common factor Adding reactants or products Inserting a coefficient between two elements in the formula of a compound Inserting coefficients before the formulas of reactants and products Altering the formulas of reactants or products
Multiplying all coefficients by a common factor Inserting coefficients before the formulas of reactants and products
In a balanced chemical equation, which of the following must be the same on both sides of the equation? Potential energy Number of atoms of each element Elements represented Phase labels Number of molecules
Number of atoms of each element Elements represented
6.25 g of hydrogen (H2) reacts with 10.6 g of oxygen (O2) to form water (H2O). The balanced chemical equation is 2 H2 (g) + O2 (g) → 2 H2O (l). Which of the two reactants is the limiting reagent? O2 is the limiting reactant because the given amount can produce less product. H2 is the limiting reactant because there are fewer grams of H2 than O2. O2 is the limiting reagent because there are fewer moles of O2 than H2.
O2 is the limiting reactant because the given amount can produce less product.
Which of the following statements about oxidation and reduction are correct? Reduction is the loss of electrons. Oxidation and reduction are opposite processes. Reduction is the gain of electrons. It is possible for an atom to lose an electron without another atom gaining an electron. Oxidation is the loss of electrons.
Oxidation and reduction are opposite processes. Reduction is the gain of electrons. Oxidation is the loss of electrons.
Which of the following statements correctly describe various examples of oxidation and reduction? Select all that apply. Oxidation may result in the loss of hydrogen atoms. Reduction may result in the loss of hydrogen atoms. Reduction is the loss of electrons from an atom. Reduction may result in the loss of oxygen atoms. Oxidation is the loss of electrons from an atom.
Oxidation may result in the loss of hydrogen atoms. Reduction may result in the loss of oxygen atoms. Oxidation is the loss of electrons from an atom.
Which of the following statements correctly describe the percent yield in a chemical reaction? Select all that apply. % yield = theoretical yield - actual yield / theoretical yield x 100 The actual yield of the reaction is obtained by calculation using the balanced equation. The actual yield is almost always less than the theoretical yield. A reaction can produce an actual yield greater than 100%. % yield = actual yield / theoretical yield x 100
The actual yield is almost always less than the theoretical yield. % yield = actual yield / theoretical yield x 100
Which of the following correctly describes the formula weight of a compound? The sum of the atomic numbers in the compound The number of formula units in a sample of a compound The sum of the charges of the ions in a compound The sum of the atomic masses of all the elements in one formula unit compound
The sum of the atomic masses of all the elements in one formula unit compound
Which of the following statements correctly describe theoretical yield in a chemical reaction? The theoretical yield is smaller than the actual yield. The theoretical yield is the maximum amount of product that can be formed. The theoretical yield is the amount of product expected from a given amount of reactant based on the balanced chemical equation. The theoretical yield considers the fact that side reactions may occur.
The theoretical yield is the maximum amount of product that can be formed. The theoretical yield is the amount of product expected from a given amount of reactant based on the balanced chemical equation.
True or false: The value of the molar mass of an element in the periodic table (in grams per mole) is the same as the value of the atomic weight (in amu).
True
Select all statements that correctly describe the operation of a pacemaker. "Fixed" rate pacemakers have replaced the early "demand" pacemakers. When a pacemaker detects that the heart is beating too slowly, it sends an electrical signal to the heart. In a lithium-iodine battery, I2 is reduced. Most pacemakers used today contain a lithium-iodine battery. When a lithium atom is oxidized it gains one electron. The life of the typical battery in a pacemaker is one year.
When a pacemaker detects that the heart is beating too slowly, it sends an electrical signal to the heart. Most pacemakers used today contain a lithium-iodine battery. In a lithium-iodine battery, I2 is reduced.
In performing mass calculations in chemical equations, which of the following is/are needed? (Select all items that are needed.) the phase of each reactant or product in the chemical equation a balanced chemical equation Avogadro's number molar mass of reactant and/or product from the chemical equation
a balanced chemical equation molar mass of reactant and/or product from the chemical equation
The _____ yield is usually less than the _____ yield
actual / experimental theoretical
The correct units for the formula weight of a substance are ______ atomic mass units (amu) grams per mole (g/mol) atomic mass units or grams per mole
atomic mass units (amu)
True or false: The same substance may appear as both a reactant and a product in a chemical reaction.
false
The ______ of a substance is reported in ______. formula weight; atomic mass units formula weight; grams molar mass; atomic mass units
formula weight; atomic mass units
The correct units for the molar mass of a substance are ______ atomic mass units or grams per mole. atomic mass units (amu). grams per mole (g/mol).
grams per mole (g/mol).
When converting from grams to number of molecules, the magnitude of the answer
increases
The amount of product that is formed from a reactant mixture is determined by the number of moles of the _____ reactant(s)
limiting
Match the terms below to correctly define limiting and excess reactants. limiting reactant - excess reactant - the reactant that is completely consumed in a reaction the reactant that Is left over when the reaction is complete
limiting reactant - the reactant that is completely consumed in a reaction excess reactant - the reactant that Is left over when the reaction is complete
Which one of the following options gives the correct procedure to calculate the number of moles of a substance, given the mass? mass x molar mass molar mass / mass mass / molar mass
mass / molar mass
In order to convert the grams of a reactant to the grams of a product, which of the following conversions are required? (Select all of the required conversion factors.) 6.02 x 10^23 molecules reactant / mol reactant mol reactant / g reactant g reactant / mol product mol product / mol reactant 6.02 x 10^23 molecules product / mol product
mol reactant / g reactant g product / mol product mol product / mol reactant
The _____ is the SI unit that expresses the amount of substance. Specifically, it is defined as the amount of substance containing the same number of entities as the number of _____ in exactly 12 g of carbon-12.
mole atoms / carbon atoms
Which one of the following options gives the correct procedure to calculate the mass of a substance, given the number of moles? moles x molar mass moles / molar mass molar mass / mole
moles x molar mass
Which of the following provides the correct mathematical operation to convert the number of atoms of a sample to the number of moles? Avogadro's number / number of atoms number of atoms x Avogadro's number number of atoms / Avogadro's number
number of atoms / Avogadro's number
Given the balanced chemical equation: 2 H2(g) + O2(g) → 2 H2O(g), match the following quantities: one molecule of oxygen - one molecule of hydrogen - one mole of oxygen - four moles of hydrogen - one molecule of water four moles of water two moles of hydrogen two molecules of water
one molecule of oxygen - two molecules of water one molecule of hydrogen - one molecule of water one mole of oxygen - two moles of hydrogen four moles of hydrogen - four moles of water
A reducing agent becomes _____ and an oxidizing agent becomes _____. oxidized; reduced reduced; oxidized
oxidized; reduced
In the reaction, 2 Ca + O2 → 2 CaO, the oxidizing agent is _____ and the reducing agent is _____
oxygen /O2 carbon / Ca
Match each type of reaction yield to the correct description. theoretical yield - actual yield - percent yield - actual yield/ theoretical yield x 100 amount of product obtained experimentally from a chemical reaction the amount of product calculated from the molar ratio in the balanced chemical equation
percent yield - actual yield/ theoretical yield x 100 actual yield - amount of product obtained experimentally from a chemical reaction theoretical yield- the amount of product calculated from the molar ratio in the balanced chemical equation
Which of the following are included in a complete balanced chemical equation? phases coefficients reaction time reaction arrow products reactants
phases coefficients reaction arrow products reactants
The boiling of water is an example of a _____ change. physical chemical
physical
The formula weight of a compound is the ______ of the atomic masses of the elements in one ______ of the compound. sum ; mole average ; mole sum ; formula unit average ; formula unit
sum formula unit
Reduction is ______ the gain of electrons by an atom. the gain of protons by an atom. the loss of electrons from an atom. the loss of protons from an atom.
the gain of electrons by an atom.
A mole is defined as ______ the number of atoms contained in exactly 1 g of the carbon-12 isotope. 6.02 x 10^23 C atoms. the number of atoms contained in exactly 12 g of the carbon-12 isotope. the number of atoms contained in exactly 12 g of C atoms.
the number of atoms contained in exactly 12 g of the carbon-12 isotope.
The amount of product generated in a chemical reaction is determined by the reactant with the smallest number of moles. the total number of moles of reactants. the reactant with the largest number of moles. the number of moles of the limiting reactant.
the number of moles of the limiting reactant.
A physical change may involve _____ a change in volume. a change in phase. a change in color. a change in shape. a change in the substances present.
volume phase shape
Match the following terms used in a chemical equation with their definitions. (l) (aq) Δ 1, 2, 3, ...
Δ - heat needs to be added for this reaction to occur (l) - this reactant or product is a liquid 1, 2, 3, ... - coefficients needed to balance an equation (aq) - this reactant or product is an aqueous solution
