Chemistry Exam 3
Is this a chemical reaction & why or why not: Propane forms a flame and emits heat as it burns
Yes; classified as combustion
Is this a chemical reaction & why or why not: A white precipitate forms when solutions of barium nitrate and sodium sulfate are mixed
Yes; classified as double replacement
The carbon tetrachloride molecule, CCl4, is
a nonpolar molecule with polar bonds.
The ammonia molecule, NH3, is
a polar molecule with polar bonds
In a molecule with covalent bonding
atoms are held together by sharing electrons
The octet rule indicates that
atoms lose, gain, or share valence electrons to have 8 valence electrons
The shape of the water molecule ( H2O) is
bent
The shape of the water molecule (H2O) is
bent
Which of the following elements does NOT exist as a diatomic molecule
carbon
What is the name of Cr(NO3)3
chromium (III) nitrate
In a ________ reaction, two or more elements or compounds form one product.
combination
The reaction of carbon with oxygen to produce carbon monoxide is an example of which class of reaction: 2C(s) + O2(g) → 2CO(g)
combination
What is the classification for this reaction: SO3 (g) + H2O (l) → H2SO4(l)
combination
The reaction of methane with oxygen to produce carbon dioxide and water is an example of which class of reaction: CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)
combustion
The types of compounds that use prefixes in their names are
covalent compounds
The following reaction takes place when an electric current is passed through water. It is an example of a ________ reaction: 2H2O(l) → 2H2(g) + O2(g)
decomposition
The correct name for the compound N2O3 is
dinitrogen trioxide
The strongest interactions between molecules of hydrogen chloride are
dipole-dipole attractions
The strongest interactions between atoms of helium, He, are examples of
dispersion forces
The strongest interactions between molecules of hydrogen, H2, are
dispersion forces
The strongest interactions between molecules of iodine, I2, are examples of
dispersion forces
The ability of an atom to attract the shared electrons in a covalent bond is its
electronegativity
Any reaction that absorbs 150 kcal of energy can be classified as
endothermic
In an endothermic reaction
energy is absorbed by the system
What type of reaction is: CH4(g) + 2O2(g) → CO2 (g) + 2H2O (g)+ 218 kcal
exothermic reaction
In an oxidation-reduction reaction, the substance oxidized always
experiences a loss of electrons
How many electrons will chlorine gain or lose when it forms an ion
gain 1
How many electrons will iodine gain or lose when it forms an ion
gain 1
In an oxidation-reduction reaction, the substance reduced always
gain of electrons
The number of valence electrons found in an atom of a Group A element is equal to
group number
An anion always
has a negative charge
An ionic compound
has a net charge of zero
The ________ is the energy difference between reactants and products in a chemical reaction.
heat of reaction
If the reaction shown below is exothermic, the energy level of the reactants is: H2(g) + O2(g) → 2H2 O(g)
higher than that of the products
The strongest interactions between molecules of ammonia, NH3, are
hydrogen bonds
The correct name for the compound IF3 is
iodine trifluoride
If the electronegativity difference between elements X and Y is 2.1, the bond between the elements X-Y is
ionic
The strongest interactions in the compound sodium fluoride, NaF, are examples of
ionic bonds
Write the name for the following compound: Fe2O3
iron (III) oxide
Fe2(SO4)3 is called
iron (III) sulfate
The shape of the carbon dioxide molecule (CO2) is
linear
How many electrons will aluminum gain or lose when it forms an ion
lose 3
Which of the following describes an oxidation reaction
loss or gain of oxygen
Double and triple bonds form because
single covalent bonds do not give all of the atoms in the molecule eight valence electrons.
What type of reaction is: 2Fe(s) + 6HCl (aq) → 2FeCl3 (aq)+ 3H2(g)
single replacement
The carbon tetrachloride molecule, CCl4, has a ________ shape
tetrahedral
The shape of the carbon tetrachloride molecule is
tetrahedral
A chemical equation is balanced when
the number of atoms of each element is the same in reactants and products
The shape of the ammonia molecule (NH3) is
trigonal pyramidal
Hydrogen sulfide, H2S, has a shape similar to
water
In this reaction, what is the substance oxidized: Zn(s) + 2 HCl(aq) → ZnCl2(aq) + H2(g)
zinc
Elements in group 2A (2) of the periodic table form ions with a charge of
2+
The name of the HSO4- ion is
Hydrogen Sulfate
The name of Al2(SO4)3 is
aluminum sulfate
How many valence electrons are in the Lewis structure of CCl4
32
In ionic compounds, ___A_____ lose their valence electrons to form positively charged ___B_____.
A: Metals & B: Cations
The formula for silver chloride is
AgCl
What is oxidized and what is reduced, respectively, in the following reaction: 2Al(s) + 3Br2(g) → 2AlBr3(s)
Al is oxidized & Br2 is reduced
What is the formula for aluminum nitrite
Al(NO2)3
The correct formula for a compound formed from the elements Al and O is
Al2O3
The ion of aluminum is
Al3+
What type of reaction: 2KClO3(s) → 2KCl(s) + 3O2(g)
Decomposition
What type of reaction: CaCO3(s) → CaO(s) + O2(g)
Decomposition
The correct formula for the compound formed from Mg and S is
MgS
The formula of copper(I) sulfide is
Cu2S
The name of PbO2 is
lead (IV) oxide
How many moles of K2SO4 are in 15.0 g of K2SO4
0.0861 moles
How many grams of hydrogen are needed to produce 1.80 g of water according to this equation: 2H2(g) + O2(g) → 2H2O(l)
0.200 g
2Mg(s) + O2(g) → 2MgO(s): The number of moles of MgO produced when 0.20 mole of O2 reacts completely is
0.40 mole
0.100 mole of lithium has a mass of
0.694g
2Mg(s) + O2(g) → 2MgO(s): How many moles of magnesium are needed to react with 0.50 mole of O2
1.0 mole
How many moles of carbon are there in 0.500 mole of C2H6
1.00 moles
Chromium metal will react with oxygen gas to produce chromium(III) oxide (molar mass = 152.0 g/mol), according to the equation below: 4 Cr(s) + 3 O2 (g) --> 2 Cr2O3 (s): If 1.48 moles of Cr is reacted with 1.03 moles of O2, which reactant is limiting and which reactant is in excess
1.03 is limiting reactant & 1.48 is excess reactant
Chromium metal will react with oxygen gas to produce chromium(III) oxide (molar mass = 152.0 g/mol), according to the equation below: 4 Cr(s) + 3 O2 (g) --> 2 Cr2O3 (s): What is the theoretical yield (in grams) of Cr2O3
104 g
Mg3N2(s) + 6H2O(l) → 3Mg (OH)2(s) + 2NH3(g): When 2 moles of Mg3N2 are allowed to react, how many moles of H2O also react
12 moles
What is the molar mass of sodium phosphate, Na3PO4
164g
The number of electrons in an ion with 20 protons and an ionic charge of 2+ is
18
How many lone pairs of electrons are in the Lewis structure of H2O
2
In the following reaction, when the equation is correctly balanced, what is the correct coefficient for sodium chloride: Pb(NO3)2(aq) + NaCl(aq) → ? PbCl2(s) + ? NaNO3(aq)
2
Given the following equation, what is the correct form of the conversion factor needed to convert the number of moles of O2 reacted to the number of moles of Fe2O3 produced: 4Fe(s) + 3O2 (g) → 2Fe2O3(s)
2 moles of Fe2O3 / 3 moles of O2
Mg3N2(s) + 6H2O(l) → 3Mg (OH)2(s) + 2NH3(g): What is the correct form of the conversion factor needed to convert the number of moles of H2O to the number of moles of NH3 produced
2 moles of NH3 / 6 moles of H2O
2Mg(s) + O2(g) → 2MgO(s): The number of moles of oxygen gas needed to react with 4.0 moles of Mg is
2.0 moles
What is the molar mass of Mg3(PO4)2, a substance formerly used in medicine as an antacid?
263g
For the reaction: 2H2O(l) + 137 kcal → 2H2 (g) + O2 (g), how many kcal are needed to form 2.00 moles O2(g)
274 kcal
Solid sodium peroxide (Na2O2) reacts with water to form an aqueous solution of sodium hydroxide and oxygen gas (O2): Write a balanced equation for the reaction, clearing showing the reactants and products and symbols for their physical states
2Na2O2(s) + 2H2O(l) --> 4NaOH(aq) + O2(g)
How many valence electrons are in the electron-dot structure for an element in group 3A (13)
3
What is the coefficient of hydrogen, H2, when the following equation is balanced: 2Al(s) + ? H2SO4(aq) --> ? Al2(SO4)3(aq) + ? H2(g)
3
The molar mass of potassium is
39.1 g
The VSEPR theory allows us to determine the most favorable
3D shape of a molecule
One mole of helium gas has a mass of
4.00g
When 10.0 g of NH3 reacts, the actual yield of N2 is 8.50 g. What is the percent yield: 4NH3(g) + 6NO(g) → 5N2(g) + 6H2O(l)
41.3%
How many kcal are produced when 32.0 g of CH4 react: CH4(g) + 2O2(g) → CO2(g) + 2H2O(g) + 218 kcal
436 kcal
How many valence electrons does nitrogen have
5
How many moles of iron are present in 3.15 × 1024 atoms of iron
5.23 moles
What is the coefficient for water in the following balanced equation: C5H12 (l)+ ? O2(g) → ? CO2(g) + ? H2O(g)
6
In the reaction of nitrogen gas, N2, with hydrogen gas, H2, to form ammonia gas, NH3 , how many moles of hydrogen are needed to react with two moles of nitrogen
6 moles
One mole of particles of any substance contains how many particles
6.02x1023
How many grams of glucose (C6H12O6) are in 3.55 moles of glucose
639g
How many atoms of neon are present in 1.30 moles of neon
7.83 × 10^23 atoms
Chromium metal will react with oxygen gas to produce chromium(III) oxide (molar mass = 152.0 g/mol), according to the equation below: 4 Cr(s) + 3 O2 (g) --> 2 Cr2O3 (s): What is the percent yield of Cr2O3 if the actual yield of Cr2O3obtained is 75.5 g
72.6%
How many valence electrons are in the Lewis structure of H2O
8
Pentane (C5H12) reacts with oxygen (O2) to form carbon dioxide (CO2) and water (H2O) according to the following reaction: C5H12 (l)+ ? O2(g) → ? CO2(g) + ? H2O(g). What is the coefficient for carbon dioxide in the balanced equation
8
What is the formula of carbon tetraiodide
CI4
Which of the following compounds contains an ionic bond
CaO
What type of reaction: S(s) + O2(g) → + SO2(g)
Combination
The name of the Cu+ ion is
Copper (I)
Which one of the following elements forms two or more ions with different ionic charges
Fe
What is the correct formula for the iron(II) ion
Fe2+
What is the correct formula for iron(III) sulfide
Fe2S3
Which one of the following compounds contains an ion with a 3+ charge
FeCl3
A polar covalent bond is found in which of these compounds
H2O
Which of the following compounds contains a polar covalent bond
HCl
What is the symbol for the ion with 19 protons and 18 electrons
K+
Ionic bonding is expected in which of these compounds
KF
Which of the following elements has the lowest electronegativity
Li
Which of the following substances contains a nonpolar covalent bond?
N2
Which of the following is an oxidation-reduction reaction
N2(g) + O2(g) → 2NO(g)
What is the formula of the nitride ion
N3-
The formula for a molecule formed from N and Cl would be
NCl3
What is the formula of a compound that contains Na+ and PO43- ions
Na3PO4
Is this a chemical reaction & why or why not: Liquid ethyl alcohol turns into a solid when placed in a low-temperature freezer
No; it's a physical change
When 3.05 moles of CH4 are mixed with 5.03 moles of O2 the limiting reactant is: CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)
O2
What is the correct formula for the oxide ion
O2-
Write the formula for the given covalent compound: tetraphosphorus hexoxide
P4O6
What type of reaction: Zn (s)+ 2HCl (aq) → ZnCl2(aq) + H2(g)
Single replacement
Write the electron-dot formula & identify electron group geometry, shape & polarity: H2O
Tetrahedral; Bent; Polar
Write the electron-dot formula & identify electron group geometry, shape & polarity: OF2
Tetrahedral; Bent; Polar
Write the electron-dot formula & identify electron group geometry, shape & polarity: CF4
Tetrahedral; Tetrahedral; Nonpolar
The compound MgCl2 is named
magnesium chloride
A(n) ________ is the smallest unit of two or more atoms held together by a covalent bond.
molecule
In a covalently bonded molecule, the number of electrons that an atom shares with others is usually equal to the number of electrons
needed to give it a stable electron configuration
The correct name of the compound NCl3 is
nitrogen trichloride
The bond in Cl2 is a(n)
nonpolar covalent bond
Avogadro's number is the number of
particles in 1 mole of a substance
Which of the following polyatomic ions has a 3- ionic charge
phosphate
The water molecule has a dipole with the negative portion
pointing towards the oxygen atom
A group of covalently bonded atoms that has an overall ionic charge is called a(n)
polyatomic ion
When linoleic acid (C18H32O2), an unsaturated fatty acid, reacts with hydrogen, it forms a saturated fatty acid. Is linoleic acid oxidized or reduced in the hydrogenation reaction: C18H32O2 + 2H2 ---à C18H36O2
reduced
The name of AgCl is
silver chloride
