Chemistry Exam 3

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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


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