CHM 105-A03 Chapter 5 Smartbook
Which reactions shown are decomposition reactions? Select all that apply. Multiple select question. Cl2(g) + Br2(l) → 2 BrCl(g) C3H4O4(aq) → C2H4O2(aq) + CO2(g) 2 NOCl(g) → 2 NO(g) + Cl2(g) AgNO3(aq) + Cu(s) → Ag(s) + CuNO3(aq)
C3H4O4(aq) → C2H4O2(aq) + CO2(g) 2 NOCl(g) → 2 NO(g) + Cl2(g) *Cl2(g) + Br2(l) → 2 BrCl(g) Reason: In a decomposition reaction, a single substance reacts to form two or more products. This is a combination reaction. *AgNO3(aq) + Cu(s) → Ag(s) + CuNO3(aq) Reason: In a decomposition reaction, a single substance reacts to form two or more products.
Identify the species that are oxidized and reduced in the reaction below. CH4O + O2 → CO2 + H2O Multiple choice question. CO2 is oxidized and H2O is reduced. O2 is oxidized and CH4O is reduced. CH4O is oxidized and O2 is reduced. CH4O is oxidized and CO2 is reduced.
CH₄O is oxidized and O₂ is reduced.
Select all that apply Which of the following substances are the products in this chemical reaction? Select all that apply. CH₃CH₂OH + 3 O₂ → 2 CO₂ + 3 H₂O Multiple select question. CH₃CH₂OH H₂O O₂ CO₂
CO₂ H₂O
What is the molar mass of calcium chloride, CaCl₂?
Ca: 40.08 Cl: 2 x 35.45 = 110.98 g/mol
Which of the following are redox reactions? (Select all of the redox reactions.) Multiple select question. 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(all combustion reactions are redox) iron rusting
Calculate the following ratio: 2.5×10⁸/1.8×10⁻⁶ Multiple choice question. 0.7 x 10¹⁴ 0.7 x 10² 1.4 x 10¹⁴ 1.4 x 10²
1.4 x 10¹⁴ *When dividing numbers in scientific notation, the coefficient of the numerator is divided by the coefficient of the denominator, while the exponent of the denominator is subtracted from that of the numerator.
B2 reacts with AB to form AB2 according to the balanced equation B2 + 2 AB → 2 AB2. If 1.5 moles of B2 are reacted with 1.5 moles of AB, the maximum amount of AB2 that can form is equal to _____ moles. Multiple choice question. 0.75 4.5 3.0 1.5
1.5 *The reaction requires 2 moles of AB for every 1 mole of B2, so AB is the limiting reagent. Each mole of AB produces 1 mole of AB2.
When the coefficient "4" precedes the reactant NaClO₃ in a balanced chemical equation, there are ______ O atoms
12
How many grams of hydrogen gas are generated when 12.66 moles of HCl react in the reaction below? 2 HCl(aq) + Ca(s) → CaCl₂(aq) + H₂(g) Multiple choice question. 25.52 g H2 12.76 g H2 6.381 g H2 12.66 g H2
12.76 g H₂
89.5 g of iron reacts with 250. g of oxygen according to the balanced chemical equation 4 Fe (s) + 3 O2 (g) → 2 Fe2O3 (s). Calculate the mass (in grams) of Fe2O3 formed. Multiple choice question. 128 g 832 g 256 g 339.5 g
128 g
3 H₂ (g) + N₂ (g) → 2 NH₃ (g) Calculate the mass of NH₃ produced by the complete reaction of 2.55 g of H2 with excess N2 according to the equation above. Multiple choice question. 1.70 g 1.69 g 21.5 g 14.4 g
14.4 g
3 H₂ (g) + N₂ (g) → 2 NH₃ (g) Calculate the mass of NH₃ produced by the complete reaction of 2.55 g of H2 with excess N₂ according to the equation above. Multiple choice question. 1.70 g 14.4 g 21.5 g 1.69 g
14.4 g.
How many grams of calcium chloride are generated when 5.19 grams of calcium react in the the reaction below? 2 HCl(aq) + Ca(s) → CaCl2(aq) + H2(g) Multiple choice question. 14.4 g CaCl2 1.87 g CaCl2 9.78 g CaCl2 5.19 g CaCl2
14.4g. CaCl₂
If the formula mass of a particular synthetic nylon is 15,367 amu, what is the molar mass of this synthetic nylon?
15,367 g/mol
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 of the following is a redox reaction? Multiple choice question. AgNO3 (aq) + NaCl (aq) → AgCl (s) + NaNO3 (aq) HF (aq) + NaOH (aq) → H2O (l) + NaF (aq) 2 SO2 (g) + O2 (g) → 2 SO3 (g)
2 SO₂ (g) + O₂ (g) → 2 SO₃ (g) *HF (aq) + NaOH (aq) → H2O (l) + NaF (aq) Reason: No oxidation numbers change in the reaction between HF and NaOH.
When the following chemical equation is balanced correctly, what is the correct coefficient for each species? (Enter ALL numbers, including the digit 1, if required.) SO2(g) + O2 (g) → SO3 (g) SO2 O2 SO3
2,1,2
Provide the correct mathematical operation to calculate the number of molecules in 2.0 mol of CH₄
2.0 mol × 6.022 × 10²³molecules/mol
How many grams of calcium are needed to generate 6.34 moles of hydrogen gas in the reaction below? 2 HCl(aq) + Ca(s) → CaCl₂(aq) + H₂(g) Multiple choice question. 6.34 g Ca 512 g Ca 12.8 g Ca 254 g Ca
254 g Ca
Given a balanced chemical equation, determine the number of conversion factors needed to determine grams of product from grams of reactant.
3
Calculate the the following product: (2.5 x 10⁸) x (1.8 x 10⁻⁶)
4.5 x 10²
A reaction is expected to produce 83.5 g of CaCO3. The percent yield is recorded as 62.5%. What is the actual mass of CaCO3 obtained? Multiple choice question. 52.2 g 134 g 74.9 g
52.2 g
Which conversion factor correct correctly describes a mass/mole/molecule relationship for HCl?
6.02 x 10²³ molecules = 1 mole
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) Multiple choice question. 82.0% 54.7% 0.820% 75.2%
82%
A particular reaction is expected to yield 125 g of calcium. The actual amount of calcium obtained is equal to 105 g. Calculate the percentage yield for the reaction. Multiple choice question. 84.0% 16.0% 119% 0.84%
84%
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) Multiple choice question. 0.910% 55.0% 91.0% 97.7%
91%
Which statement is correct about the ratio of reactants to products in a chemical equation? Multiple choice question. An unbalanced 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 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.
Which statements about decomposition reactions are correct? Select all that apply. Multiple select question. In a decomposition reaction, one element in the reactant is replaced by another in the product. A decomposition reaction always produces one or more elements. A decomposition reaction begins with a single reactant. The reactant in a decomposition reaction is always a compound.
A decomposition reaction begins with a single reactant. The reactant in a decomposition reaction is always a compound.
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 Multiple choice question. The reactants are in the correct ratio so that there is no excess reactant. Not enough information is given to determine the answer. B is the excess reactant. A is the excess reactant.
A is the excess reactant *Calculate the moles of product formed when 2 moles of A reacts and when 1 mole of B reacts.
A mole is defined as the number of atoms contained in exactly 12 g of C atoms. 6.02 x 1023 C atoms. the number of atoms contained in exactly 12 g of the carbon-12 isotope. the number of atoms contained in exactly 1 g of the carbon-12 isotope.
A mole is defined as the number of atoms contained in exactly 12 g of the carbon-12 isotope.
Which of the following statements correctly describe oxidizing agents and reducing agents? Select all that apply. Multiple select question. 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. *Reason: A reducing agent causes an element to be reduced. *Reason: A reducing agent is oxidized.
Compound B2 (represented by the red spheres) reacts with AB, as shown in the illustration. From the illustration, the reagent in excess is _____, and the limiting reagent is _____.
B₂; AB
Which of the following statements about oxidation and reduction are correct? Select all that apply. Multiple select question. It is possible for an atom to lose an electron without another atom gaining an electron. Oxidation and reduction are opposite processes. Reduction is the gain of electrons. Reduction is the loss of electrons. Oxidation is the loss of electrons.
Oxidation and reduction are opposite processes. Reduction is the gain of electrons. Oxidation is the loss of electrons. *Oxidation and reduction always occur together in a single reaction.
Which option below correctly defines the term "limiting reactant" in a chemical reaction? Multiple choice question. The reactant that has the smallest molar mass The reactant that is completely used up in the reaction The reactant that is present in the smallest amount
The limiting reactant is the reactant that is completely used up in the reaction. *This may or may not be the reactant that is present in the smallest amount.
Which of the following correctly describes the formula weight of a compound? Multiple choice question. The sum of the atomic masses of all the elements in one formula unit compound The number of formula units in a sample of a compound The sum of the atomic numbers in the 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
Which of the following statements correctly describe theoretical yield in a chemical reaction? Select all that apply. Multiple select question. 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 considers the fact that side reactions may occur. The theoretical yield is the amount of product expected from a given amount of reactant based on the balanced chemical equation.
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.
Which of the following can be determined using a balanced equation and the quantities of reagents used? Multiple choice question. Theoretical yield Actual yield Percent yield
Theoretical yield *The theoretical yield can be calculated given the amount of the reactant and a balanced chemical equation. The percent yield is determined from the actual yield, which must be measured.
Which of the following can decrease the actual yield of a chemical reaction? (Select all that apply.) Multiple select question. The product is contaminated. Undesired side reactions occur. Material is lost when transferring product. A purification step is carried out.
Undesired side reactions occur. Material is lost when transferring product. A purification step is carried out. *Contaminants increase weight
Given the balanced chemical reaction, 2 HCl(aq) + Na₂CO₃(aq) → 2 NaCl(aq) + H₂O(l) + CO₂(g), rank 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 Na₂CO₃ 1 mol HCl 3 mol HCl 4 mol Na₂CO₃
What is the limiting reagent?
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.) Multiple select question. 2 mol Na2 CO3/1 mol H2O 1 mol HCl/2 mol NaCl 1 mol Na2CO3/2 mol NaCl 1 mol CO2/2 mol HCl
Which ratio matches the coefficient in the balanced reaction?
Which of the following steps would be required to convert between the masses of any two substances involved in the same chemical reaction? Select all that apply. Multiple select question. Write a conversion factor using the coefficients from the balanced equation, and convert to moles of the second substance. Convert from the given mass to moles of the same substance. Calculate the molar masses of all substances in the reaction. Write a balanced chemical equation for the reaction. Use the coefficients from the balanced equation to convert directly from the mass of one substance to the other.
Write a conversion factor using the coefficients from the balanced equation, and convert to moles of the second substance. Convert from the given mass to moles of the same substance. Write a balanced chemical equation for the reaction.
Which reactions shown are replacement reactions? Select all that apply. Multiple select question. CaO(s) + CO2(g) → CaCO3(s) 2 NO3(g) → 2 NO2(g) + O2(g) Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s) AgNO3(aq) + NaBr(aq) → AgBr(s) + NaNO3(aq)
Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s) AgNO3(aq) + NaBr(aq) → AgBr(s) + NaNO3(aq) *ALWAYS 2 reactants and 2 products
The ____ yield is usually less than the ____ yield.
actual; theoretical
The correct units for the formula weight of a substance are ______
amu
The law of conservation of matter states that
atoms cannot be created or destroyed in a chemical reaction
In a _____ reaction, two or more substances react to form a single product.
combination
In a ______ reaction, two reactants exchange components to form two new products. Multiple choice question. double replacement combination decomposition single replacemen
double replacement
The ______ of a substance is reported in ______. Multiple choice question. formula weight; atomic mass units formula weight; grams molar mass; atomic mass units
formula weight; atomic mass units
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.) Multiple select question. g product/mol product mol reactant/g reactant 6.02 × 10²³ molecules reactant/mol reactant 6.02 × 10²³ molecules product/mol product mol product/mol reactant
g. product/mole product; mol reactant/g.reactant; mol product/mol reactant
The correct units for the molar mass of a substance are ______ Multiple choice question. grams per mole (g/mol). atomic mass units or grams per mole. atomic mass units (amu).
g/mol
As a result of the law of conservation of mass, a balanced chemical equation must: Multiple choice be balanced by having the same number of product substances as reactant substances. contain a gas on both sides of the chemical equation. have the same number of atoms on each side of the equation
have the same number of atoms of each type on both sides of the equation.
When converting from grams to number of molecules, the magnitude of the answer (increases/decreases).
increases
The amount of product that is formed from a reactant mixture is determined by the number of moles of the ____ reactant(s).
limiting
The ____ is the reactant that is completely used up in a reaction.
limiting reagent
Which one of the following options gives the correct procedure to calculate the number of moles of a substance, given the mass? Multiple choice question. molar mass/mass mass x molar mass mass/molar mass
mass/molar mass
In performing mass calculations in chemical equations, which of the following is/are needed? (Select all items that are needed.) Multiple select question. the phase of each reactant or product in the 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 a balanced chemical equation
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
The formula weight of a compound expressed in amu is numerically the same as the mass of 1____ of the compound expressed in____.
mole; grams
formula weight is also called
molecular mass
Which one of the following options gives the correct procedure to calculate the mass of a substance, given the number of moles? Multiple choice question. molar mass/moles moles/molar mass moles x molar mass
moles x molar mass
A reducing agent becomes _____ and an oxidizing agent becomes _____. Multiple choice question. oxidized; reduced reduced; oxidized
oxidized; reduced
The new substances that are formed in a chemical reaction are called _____. Multiple choice question. reactants coefficients products
products
Which of the following are included in a complete balanced chemical equation? (Select all that apply.) reaction time reactants products coefficients reaction arrow phases
reactants products coefficients reaction arrow phases
The formula weight of a compound is the ______ of the atomic masses of the elements in one ______ of the compound. Multiple choice question. sum; formula unit average; formula unit average; mole sum; mole
sum; formula unit
The amount of product generated in a chemical reaction is determined by
the number of moles of the limiting reactant
Which conversion factor should be used to convert grams of carbon dioxide to moles of carbon dioxide?
to convert grams to moles: g. x (1 mole/molar mass in grams)
Which statements about single replacement reactions are correct? Select all that apply. Multiple select question. In a single replacement reaction, one reactant is converted to two or more products. In a single replacement reaction, one element in the reactant is replaced by another in the product. A single replacement reaction follows the general scheme AB + CD → AD + CB. An element is always a reactant in a single replacement reaction.
In a single replacement reaction, one element in the reactant is replaced by another in the product. An element is always a reactant in a single replacement reaction.
Which of the following actions are permitted in balancing a chemical equation? Multiple select question. 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 Multiplying all coefficients by a common factor
1 formula unit of KOH has a mass of ____ amu; hence 1 mol of KOH has a mass of ____ g. (Remember to read atomic masses to 4 significant figures before adding them together.)
K: 39.10 O: 16.00 H: 1.008 56.11 amu = 56.11 g.
Calculate the formula weight of Mg₃(PO₄)₂.
Mg: 3 x 24.305= 72.915 P: 2 x 30.974 =61.948 O: 8 x 15.999=127.992 Total amu: 262.855
If the actual yield is measured in millgrams, what units of theoretical yield should be used to find percent yield? Multiple choice question. Any mass unit Moles Grams Milligrams
Milligrams
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; Zn
In a balanced chemical equation, which of the following must be the same on both sides of the equation?
Number of atoms of each element Elements represented
Provide the correct mathematical operation to convert the number of atoms of a sample to the number of moles
Number of atoms/Avogadro's Number
Given the balanced equation below, determine the moles of HCl required and the mass of AgCl formed from the complete reaction of 18.3 g of Ag₂S. Ag₂S (s) + 2 HCl (aq) → 2 AgCl (s) + H₂S (g) Multiple select question. 10.6 g of AgCl 7.38 x 10-2 mol HCl 0.148 mol HCl 21.2 g of AgCl
0.148 mol HCl 21.2 g of AgCl
Which of the following conversion factors cannot be possible for a chemical substance? (Select all that are not possible.) Multiple select question. 0.98 g/1 mol 3256.2 g/1 mol 3.51 g/1 mol 2.02 g/1 mol
0.98 g/1 mol and 3.51g/1 mol *3256.2 g/1 mol Reason: There are many combinations of atoms that can generate a molecule with this molar mass. Molar masses can be very large. *3.51 g/1 mol Reason: 3.51 g is less than the molar mass of helium, so the only element that could be in the molecule is hydrogen. Since 3.51 g is not an exact multiple of H's molar mass, this molar mass is not possible. *2.02 g/1 mol Reason: Hydrogen, H2, has a molar mass of 2.02 g/mol.
Balance Al₂S₃(s) + H₂O (l) → Al(OH)₃ (aq) + H₂S (g)
1, 6, 2, 3
What order of steps are 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?
1. Balanced equation 2. Convert the Given Mass to Moles Using Molar Mass. Convert Moles of a to B using the balanced equation. 3. Convert moles of second substance to mass its using molar mass
order the steps necessary to calculate the mass of product formed in a chemical reaction, given the masses of all reactants. Start with the first step at the top of the list.
1. Determine # moles of each reactant by dividing its mass by molar mass 2. Determine amount of product that can be formed from each product by using mole ratios 3. Identify limiting reactant(least) 4. Multiply # moles formed from limiting reactant by the molar mass of the product
Which of the following statements correctly describe the steps used to determine which reactant in a given reaction is limiting? Select all that apply. Multiple select question. Calculate the amount of product that could be formed from each reactant. Calculate the molar masses of any reactants for which a mass has been given. The maximum product possible is given by the sum of the amounts of product formed from each reactant. The reactant that has the greatest mass at the beginning of the reaction is in excess. The reactant that produces the least amount of possible product is the limiting reactant.
Calculate the amount of product that could be formed from each reactant. Calculate the molar masses of any reactants for which a mass has been given. The reactant that produces the least amount of possible product is the limiting reactant.
Given 86.5 g Na2CO3 and the balanced chemical reaction, 2 HCl(aq) + Na2CO3(aq) → 2 NaCl(aq) + H2O(l) + CO2(g), order the following conversion factors in order of their use in calculating the mass of NaCl that can be can generated.
Conversion factors for Steps 1. 1 mole Reactant/Reactant MM 2. mole(s) product/mole(s) reactant 3. MM Product/1 mole Product
Calculate the formula weight of Cs₂S.
Cs: 2 x 132.91= 265.82 + S: 1 x 32.065= 32.065 =297.885
What is the percent yield of a reaction if the theoretical yield is 33.62 g, and 28.33 g of product is recovered? Multiple choice question. 0.8427% 15.73% 84.27% 1.187%
Divide the actual yield of the product by the theoretical yield and multiply by 100 % yield= 28.33/33.62x100 =84.27%
True or false: Chemical equations can be balanced by adding coefficients in front of chemical formulas and by changing the subscripts in a chemical formula. True False
F
True or false: In order to balance the reaction of hydrogen gas (H₂) with oxygen gas (O₂) to form H₂O, a student adds a subscript of 2 to H₂O (forming H₂O₂). This is an acceptable method of balancing the reaction described.
F
Which of the following statements correctly describe various examples of oxidation and reduction? Select all that apply. Multiple select question. 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 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. *Reason: Reduction may result in the gain of hydrogen atoms. *Reason: Reduction is the gain of electrons from an atom.
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
In the reaction, 2 Ca + O2 → 2 CaO, the oxidizing agent is___ and the reducing agent is __.
O₂, Ca
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).
T
correctly describe the percent yield in a chemical reaction
The actual yield is almost always less than the theoretical yield. % yield = actual yield/theoretical yield × 100
Which of the following pieces of information are necessary to calculate the formula weight of a compound? Select all that apply. Multiple select question. The formula of the compound The mass of a sample of the compound The atomic masses of each of the elements that make up the compound The physical properties of the compound
The formula of the compound The atomic masses of each of the elements that make up the compound
