Chemistry: Chapter 4
Which of the following compounds has the largest molar mass?
H2SO4
Which of the following quantities is known as the atomic mass unit (amu)?
1.661 × 10-24 g
What is the molar mass of calcium chloride, CaCl2, reported to six significant figures?
110.984 g/mol
What is the molar mass of calcium chloride, CaCl2?
110.984 g/mol
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
Match each reaction type on the left with a representative reaction on the right. 1: Combination 2: Single replacement 3: Double replacement 4: Decomposition
1: 2SO2(g) + O2(g) → 2SO3(g) 2: AgCl(s) + Na(s) → Ag(s) + NaCl(aq) 3: Pb(NO3)2(aq) + 2KI(aq) → PbI2(s) + 2KNO3(aq) 4: H2CO3(aq) → H2O(ℓ) + CO2(g)
Match each reaction type on the left with a representative reaction on the right. 1: combination 2: single replacement 3: double replacement 4: decomposition
1: Zn(s) + Cl2(g) → ZnCl2(s) 2: Cu(NO3)2(s) + Mg(s) → Cu(s) + Mg(NO3)2(aq) 3: Ca3(PO4)2(s) + 6HCl(aq) → 2H3PO4(aq) + 3CaCl2(aq) 4: 2H2O(l) → 2H2(g) + O2(g)
Which of the following gives the correct mathematical operation to calculate the number of molecules in 2.0 mol of CH4?
2.0 mol × 6.022 × 1023 molecules / 1 mol
How many atoms are contained in 3.46 moles of helium?
2.08 × 1024 helium atoms
How many moles of methane, CH4, will react with 4.4 moles of oxygen, O2, given the balanced chemical reaction below? CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)
2.2 mol CH4
How many moles of Au correspond to 1.52 × 1024 Au atoms? Avogadro's number is 6.02 × 1023.
2.52
Given the balanced equation Ag2S(s) + 2HCl(aq) → 2AgCl(s) + H2S(g), determine the moles of HCl required and the mass of AgCl formed from the complete reaction of 18.3 g of Ag2S.
21.2 g of AgCl are formed. 0.148 mol HCl is required.
Identify the one decomposition reaction shown.
2HgO(s) → 2Hg(ℓ) + O2(g)
Identify all the decomposition reactions shown. (Select all that apply)
2Ni2O3(s) → 4Ni(s) + 3O2(g) H2CO3(aq) → CO2(g) + H2O(ℓ) 2KClO3(s) → 2KCl(s) + 2O2(g)
When the following chemical equation is balanced correctly, what is the correct coefficient for each species? (Enter all the numbers, including the digit 1, if required.) SO2(g) + O2(g) → SO3(g)
2SO2 1O2 2SO3
How many moles of water are contained in 1.99 × 1026 molecules of water?
3.31 × 102 moles of water
How many moles of water are contained in 1.99 × 1026 molecules of water?
3.31 × 10^2 moles of water
Which of the following options give the correct number of moles AND the correct number of atoms in a 3.54 g sample of copper (Cu)? Avogadro's number is 6.022 x 1023, and the molar mass of copper is 63.55 g/mol. Select both correct answers.
3.35 x 10^22 atoms of Cu 5.57 x 10^2 mol of Cu
Select all the combination reactions from the list below. Select all that apply.
4Al(s) + 3O2(g) → 2Al2O3(s) 4P(s) + 5O2(g) → 2P2O5(s)
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?
52.2 g
One formula unit of KOH has a mass of _________ amu; hence 1 mol of KOH has a mass of __________ g. Read atomic masses to four significant figures before adding them together.
56.11 56.11
The number of entities in a mole (to 4 significant figures) is equal to ___________ × 1023 and is called ___________ number.
6.022 Avogadros
Which of the following correctly reflects Avogadro's number?
6.022 x 1023 atoms / 1 mole atoms
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.
84.0%
Which of the following observations would be evidence that a chemical change is occurring? Select all that apply.
A reaction solution suddenly becomes hot. Two colorless solutions turn blue when combined. A solid precipitate forms.
Identify the limiting reagent in the following chemical reaction if one begins with 9 moles of aluminum and 9 moles of bromine: 2Al(s) + 3Br2(ℓ) → 2AlBr3(s)
Br2
What is a formula unit?
The lowest whole number ratio of ions in an ionic compound formula
What is the definition of the molar mass of an element?
The mass of 1 mole of atoms
What information is contained in a chemical formula? Select all that apply.
The relative number of each type of atom The identity of the elements present in a substance
When performing mass calculations based on a balanced chemical equation, what do the coefficients represent?
The relative numbers of moles of each substance
For a variety of reasons, both physical and experimental, the _______ yield is typically less than the _______ yield.
actual theoretical
The conversion of potassium chlorate to potassium chloride and oxygen is an example of a __________ change.
chemical
Two clear, colorless solutions were mixed, resulting in the formation of a yellow solid. This observation is evidence of a
chemical change
The correct units for the molar mass of a substance are ____.
grams per mole (g/mol)
The ___________ __________ is the reactant that is completely used up in a reaction.
limiting reactant
How many nitrogen atoms are contained in the formula of pyridine, C5H5N?
one
The new substances that are formed in a chemical reaction are called _____.
products
Which one of the following options gives the correct procedure to calculate the number of moles of a substance, given the mass?
Mass / molar mass
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). Is this an acceptable method of balancing the reaction described?
No
How many moles of glucose are contained in 8.3 × 1021 molecules of glucose?
0.014 mol glucose
Which of the following conversion factors cannot be possible for a chemical substance?
0.98 g / 1 mol 3.51 g / 1 mol
True or false: The same substance may appear as both a reactant and a product in a chemical reaction.
False
Which conversion factor can be generated from the balanced chemical reaction below? CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)
1 mol CO2 / 2 mol H2O
Which conversion factor should be used as written to convert grams of carbon dioxide to moles of carbon dioxide?
1 mol CO2 / 44.01 g CO2
Given the balanced chemical reaction 2HCl(aq) + Na2CO3(aq) → 2NaCl(aq) + H2O(ℓ) + CO2(g), which of the following conversions can be generated?
1 mol Na2CO3 / 2 mol NaCl 1 mol CO2 / 2 mol HCl
Which of the following can never be done when balancing a chemical equation?
Change the subscripts in a formula of a reactant or product.
Identify all of the single displacement reactions shown.
Cl2(g) + 2NaBr(aq) → 2NaCl(aq) + Br2(aq) Zn(s) + Cu(NO3)2(aq) → Cu(s) + Zn(NO3)2(aq)
Given the balanced chemical equation 2H2(g) + O2(g) → 2H2O(g), 2 moles of hydrogen react with _______ mole(s) of oxygen to generate _______ mole(s) of water.
*1 *2
Which of the following are described in a complete balanced chemical equation? Select all that apply.
*Reactants *Reaction arrow *Coefficients *Physical states *Products
Given the balanced chemical equation 2H2(g) + O2(g) → 2H2O(g), match the following quantities:
1 molecule of oxygen - 2 molecules of water 1 mole of hydrogen - 1 mole of water 1 mole of oxygen - 2 moles of hydrogen 4 moles of hydrogen - 4 moles of water
Correctly order the steps necessary to balance a chemical equation.
1. Count the number of moles of each atom on each side of the equation 2. Determine the elements that are not balanced 3. Use coefficients to balance one element at a time 4. Do a final check to make sure the equation is balanced
B2 reacts with AB to form AB2 according to the balanced equation B2 + 2AB → 2AB2. 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.
1.5
When the coefficient "4" precedes the reactant NaClO3 in a balanced chemical equation, there are ______ oxygen atoms.
12
Given the balanced equation 3H2(g) + N2(g) → 2NH3(g), calculate the mass of NH3 produced by the complete reaction of 2.55 g of H2.
14.4 g
Match the following terms used in a chemical equation with their definitions. 1: (l) 2: (aq) 3: Δ 4: 1, 2, 3, ...
1: This reactant or product is a liquid. 2: This reactant or product is an aqueous solution. 3: Heat needs to be added for this reaction to occur. 4: Coefficients needed to balance an equation
How many moles of methane, CH4, will react to form 3.2 moles of carbon dioxide, CO2, given the balanced chemical reaction shown below? CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)
3.2 mol CH4
Consider the reaction: 4KO2(s) + 2CO2(g) → 2K2CO3(s) + 3O2(g) If 8 moles of KO2 are reacted with 8 moles of CO2, the maximum amount of K2CO3 that can form is equal to _______ moles.
4
Select all of the statements below that correctly interpret the following balanced equation: 4C(s) + S8(s) → 4CS2(l)
4 atoms of carbon react with 1 molecule of S8 to form 4 molecules of CS2. 4 moles of carbon react with 1 mole of S8 to form 4 moles of CS2. Carbon and S8 are reactants and CS2 is the product.
Which of the following are necessary in order to perform mass calculations from a chemical equation? Select all that apply.
A balanced equation The molar masses of the reactants and products
Identify all of the double displacement reactions shown. Select all that apply.
AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq) HNO3(aq) + NaOH(aq) → NaNO3(aq) + H2O(ℓ)
Balance the unbalanced equation below, using lowest possible whole-number coefficients, then match each substance to the correct coefficient as indicated. Al2S3(s) + H2O(ℓ) → Al(OH)3(aq) + H2S(g)
Al2S3 - 1 H2O - 6 Al(OH)3 - 2 H2S - 3
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
How many C, H, and O atoms are found in the products of the following reaction? (Match each atom with the correct number.) CH3CH2OH(ℓ) + 3O2(g) → 2CO2(g) + 3H2O(g)
C= 2 O= 7 H= 6
Which of the following substances are the products in this chemical reaction? Select all that apply. CH3CH2OH + 3 O2 → 2 CO2 + 3 H2O.
CO2 H2O
Which of the following statements are correct about the compound whose chemical formula is (NH4)2CO3? Select all that apply.
Each formula unit contains two nitrogen atoms. Each ammonium ion contains one nitrogen and four hydrogen atoms.
In a balanced chemical equation, which of the following must be the same on both sides of the equation? Select all that apply.
Elements represented Number of moles of each element
Gift bags are being made for a birthday party using a pre-purchased kit containing 25 pencils, 50 lollipops, and 35 erasers. Each bag must contain the following items in the proportions listed here: 2 pencils, 4 lollipops, and 3 erasers. Which item is the limiting reagent?
Erasers
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.
False
Which of the following actions are permitted in balancing a chemical equation?
Multiplying all coefficients by a common factor Inserting coefficients before the formulas of reactants and products
Select all the combination reactions from the list below. Select all that apply.
NH3(g) + HCl(g) → NH4Cl(s) SO3(g) + H2O(ℓ) → H2SO4(aq) 2Ca(s) + O2(g) → 2CaO(s)
Select all of the statements below that correctly interpret the following balanced equation: 4HCl(aq) + MnO2(s) → MnCl2(aq) + 2H2O(l) + Cl2(g)
The MnCl2 produced is dissolved in water. HCl is a reactant in this equation. Water is both a solvent and a product in this reaction.
What is the definition of the limiting reactant in a chemical reaction?
The reactant that is completely consumed in the reaction
Which of the following correctly describes the formula mass of a compound?
The sum of the atomic masses of all the elements in the compound.
Which of the following statements are true about the theoretical yield? (Select all statements that are true.)
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.
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 mass (in amu).
True
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 mass (in amu). True false question.
True
The formula mass of a compound expressed in __________ is numerically the same as the mass of one mole of the compound expressed in ___________.
amu grams
The mass of one-twelfth of a carbon-12 atom is 1.661 × 10-24 g. This quantity is known as one _____________ ______________ unit.
atomic mass
The law of conservation of mass states that matter can be neither created nor destroyed in a chemical process. Therefore any chemical reaction that we write must be _______
balanced
When converting from moles of molecules to number of molecules, the numerical value 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.
limiting
The term mole is abbreviated as _________
mol
For an element, the mass of Avogadro's number of atoms is known as the ______ mass.
molar
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
Which of the following provides the correct mathematical operation to convert the number of atoms of a sample to the number of moles?
number of atoms / Avogadro's number
In a chemical reaction, the starting materials are called ____________.
reactants
The molecular mass of a compound is the _______ of the atomic masses of the elements in one ________ of the compound.
sum molecule
A chemical change must involve ______
the formation of new substances.
A chemical equation must be balanced, so that it will obey ______.
the law of conservation of mass
A mole is defined as ____.
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 number of moles of the limiting reactant.
