week 5

If a compound's formula mass is experimentally determined to be 26, the chemical formula could be:

C2H2 H=1.008×2=2.016 C=12.011×2=24.022

A(n) __________ is used between resonance forms to indicate that the actual structure exists as an average.

DOUBLE HEADED ARROW

Using the chemical equation provided, identify which of the following are the reactants. 4Fe+3O2⟶2Fe2O3

Fe O2

Which phase exhibits the weakest intermolecular forces?

GASES

Which of the following does NOT exhibit hydrogen bonding?

HBr

Polar molecules have a partial positive charge on one side and a partial negative charge on the other side, a separation of charge called a dipole. Which of the following molecules has this kind of a dipole?

HCl

Resonance forms differ in

arrangement of electrons

Water (H2O) can act as

both acid and base

Which type of intermolecular forces are the strongest in CH3Cl?

dipole-dipole

To convert mass of an atom in grams to moles you must _________ the molar mass.

divide by

Using the appropriate guidelines, determine the oxidation number for sulfur in the polyatomic ion SO2−3.

+4

How many moles of barium are in a 25.0 g sample of barium?

0.182

How many moles are in 25 grams of HF?

1.2

How many moles are in 81 g of iron?

1.5

If 50.0 g of nitrogen dioxide and 15.0 g water react according to the following equation, how many grams of nitrogen monoxide will form? 3NO2+H2O→2HNO3+NO

10.9

If the theoretical yield of a reaction is 100 grams, which value for actual yield is physically impossible?

110

Given the following equation, 2 KClO3⟶2 KCl+3 O2 how many moles of O2 can be produced from 8.60 moles KClO3?

12.9 8.6 x 3/2 = 12.9

Hydrogen peroxide, H2O2, can undergo spontaneous decomposition into water H2O and oxygen O2. Write the balanced chemical reaction with the simplest whole number coefficients. Do not include the states of the reactants or products.

2H2O2⟶2H2O+O2

Determine a balanced equation for the reaction of molecular nitrogen (N2) and oxygen (O2) to form dinitrogen pentoxide

2N2+5O2 ⟶ 2N2O5

What is the coefficient for O2 in the balanced version of the following chemical equation: C2H4+O2→CO2+H2O

3 First, write the unbalanced equation: C2H4+O2→CO2+H2O To balance C and H, add a coefficient of 2 in front of CO2 and a coefficient of 2 in front of H2O: C2H4+O2→2 CO2+2 H2O To balance O, add a coefficient of 3 in front of O2: C2H4+3 O2→2 CO2+2 H2O The equation is now balanced. The coefficient in front of O2 is 3.

If we wish to convert a value in years into days, a conversion factor we could use would be:

365 days/1 year

Which of the following is true of a resonance hybrid? (select all that apply)

It has some characteristics of its resonance forms. It is the average of all resonance forms.

At room temperature, n-pentane is a liquid and neopentane (2, 2-dimethylpropane) is a gas. Both compounds are nonpolar hydrocarbons. Which of the following forces is primarily responsible for this difference?

LONDON DISPERSE

________ is the extent to which a reaction's theoretical yield is achieved.

Percent yield

Identify which element is reduced in the following reaction. C+H2SO4→CO2+SO2+H2O

S

Identify if the equation below represents a redox reaction and if appropriate, name the oxidant and the reductant: C2H4(g)+3O2(g)⟶2CO2(g)+2H2O(l)

This is a redox reaction. The reducing agent is ethylene, C2H4. The oxidizing agent is oxygen, O2.

If we expect a precipitate to be formed in a certain reaction that takes place in solution, this implies that: Select the correct answer below: the products are soluble at least one of the products is insoluble precipitation is not related to the solubility of a reaction there is not enough information to answer this question

at least one of the products is insoluble

Hydrogen bonds are formed between hydrogen and

electronegative atoms

Is the following process endothermic or exothermic? CO2(s)⟶CO2(g)

endothermic

You try dissolving solid potassium bromide, KBr, in water, and you observe that the solution becomes cold to the touch. Is the dissolution of KBr endothermic or exothermic?

endothermic

Is the following process endothermic or exothermic? H2O(g)⟶H2O(l)

exothermic

Is the following process endothermic or exothermic? H2O(l)⟶H2O(s)

exothermic

This is the reaction that happens inside of a hot pack found in emergency kits: CaCl2(s)⟶CaCl2(aq) Is the reaction endothermic or exothermic?

exothermic

In which compound does oxygen have an oxidation number other than −2?

h2o2

In an endothermic reaction, do the reactants or the products have more heat energy?

products

Which will be the solid product when strontium bromide and potassium sulfate react? Select the correct answer below: potassium bromide potassium sulfate strontium sulfate strontium bromide

strontium sulfate

Intermolecular forces that occur between neutral atoms and molecules are called

van der waal

In the polar molecule HBr, what charge does the Br bear?

partial neg

Substances on the same side of a chemical equation are separated by a

plus sign

Substances that are only present when a chemical reaction is complete are called

products

If 11.7 g of aluminum reacts with 37.2 g of copper (II) sulfate according to the following reaction, how many grams of aluminum sulfate will be produced? 2Al+3CuSO4→Al2(SO4)3+3Cu Your answer should have three significant figures. (Round your answer to the first decimal place.)

26.6

According to the following reaction, if 69g of KClO3 decomposes, how many grams of oxygen will form: 2KClO3→2KCl+3O2

27

What is the percent yield of sodium hydroxide in the given reaction? The reaction was performed using 45 g NaHCO3 and 18 g NaOH were produced. NaHCO3⟶NaOH+CO2

84

In the equation 4A+2B→3C, if 12 molecules of A react, how many molecules of C will we get?

9

how many grams of H2O can be formed from 6.12g NH3?

9.71

What is the formula mass in atomic mass units, for H2SO4?

98.079

From the following balanced equation, CH4(g)+2O2(g)⟶CO2(g)+2H2O(g) how many grams of H2O can be formed from 1.25g CH4?

2.81

In the equation 5Z→2A+3B, how many molecules of Z must react to give 15 molecules of B?

25 If we expect to get five times as many molecules of B as are listed in the chemical equation, we must also multiply the number of molecules of Z by five, and 5×5=25.

A block of lead weighs 11.3 grams. How many atoms of lead are in this sample?

3.28×1022 atoms

What is the percent yield of CO2 if a reaction starts with 91.3 g C3H6 and produces 87 g CO2?

30.3

Identify which of the following is soluble in water.

CsF

Acids and bases can neutralize each other in double displacement reactions. For example, if hydrogen chloride (a strong acid, HCl) is mixed with sodium hydroxide (a strong base, NaOH), the products are water, H2O, and salt, NaCl. Write the balanced double displacement reaction with the simplest whole number coefficients. Do not include the states of the reactants or products. Do not include a coefficient when it has a value of 1.

HCl+NaOH⟶H2O+NaCl

Polar molecules have attractive dipole-dipole interactions when the dipoles are arranged in which of the following geometries?

HEAD TO TAIL SIDE TO SIDE - ANTI PARA

Which compound can exhibit hydrogen bonding between its molecules?

HOCH2CH2OH

Between Cl2 and I2 , which has the higher boiling point and why?

I2 because it has higher molar mass, and, therefore, stronger dispersion forces.

Dispersion forces increase with

INCREASING SURFACE AREA

The presence of an instantaneous dipole can distort the electrons of a neighboring atom or molecule, producing ___________________.

INDUCED DIPOLE

1.0 g P4O10 combines with 2.0g PCl5. Which is the limiting reactant?

PCl5

2Li+S→Li2S is a redox reaction. Identify which of the following is the oxidizing agent and its change in oxidation number.

S is the oxidizing agent, oxidation change from 0 to −2

Identify the oxidizing agent in the following reaction: Cr++Sn4+→Cr3++Sn2+

Sn4+

2 Sr+O2→2 SrO is a redox reaction. Which of the following is the reducing agent and its change in oxidation number? Select the correct answer below: O is the reducing agent, oxidation change from 0 to +2 Sr is the reducing agent, oxidation change from 0 to +2 O is the reducing agent, oxidation change from 0 to −2 Sr is the reducing agent, oxidation change from 0 to −2

Sr is the reducing agent, oxidation change from 0 to +2

Which best describes the dipole-dipole attractions? They are specifically the interaction between:

TWO FORMAL OR PERMANENT

Balance the following equation: X2+Y2⟶XY3

X2 + 3Y2 = 2XY3

A mole is defined as the number of atoms in an exact mass of which isotope?

carbon 12

What is the symbolic representation of a chemical reaction with identities and relative quantities known as?

chemical equation

Which type of anion will typically result in an insoluble compound?

chromate

In a chemical equation, the number of molecules of a particular compound that are participating in the chemical reaction is indicated by a

coeffient

If a compound's chemical formula was experimentally determined to be 18, the chemical formula could be:

h2O H=1.008×2=2.016 O=15.999×1=15.999

Which type of intermolecular force is strongest in HF

hydrogen bonding

The kinetic energies of molecules are responsible for:

increasing the distance between particles

Which of the following reactions is stoichiometrically equivalent to the reaction shown below? Pb(OH)4+2H2SO4→Pb(SO4)2+4H2O

2Pb(OH)4+4H2SO4→2Pb(SO4)2+8H2O

Choose the coefficient for SiO2 in the balanced version of the following chemical equation, using only whole numbers: Si2H6+O2→SiO2+H2O

4

using the chemical equation provided, identify which of the following are the coefficients of the reactants. 4Fe+3O2⟶2Fe2O3

4 3

How many barium atoms are in a 9.8×10−21 gram sample? Use 6.022×1023 atoms per mole for Avogadro's number. Your answer should have two significant figures.

43

A sample of lithium has a mass of 0.0624 grams. How many atoms are present in this sam

5.41×1021 atoms

If 45.0 g CH3OH react, how many grams of water can we expect to be produced according to the following equation: 2CH3OH+3O2→2CO2+4H2O

50.6

etermine the mass (in grams) of C2H6O necessary to produce 12.0 g CO2 in the following reaction: C2H6O+3O2→2CO2+3H2O

6.28

How many moles of hydrogen atoms are there in 120 g of C6H12O6?

8

Calculate the number of moles in 8.8 g of titanium (Ti).

8.8gTi×1molTi47.867gTi=0.18molTi 0.18

Which of the following pairs of molecules experience dipole-dipole attraction?

POLAR/POLAR

What is being illustrated by the dotted lines in the following image?

This illustrates the electrostatic attraction between the partially positive end of one polar molecule and the partially negative end of another.

Which of the following conditions is/are true when a transition between states is observed in the order of solid→liquid→gas?

both a and b

Acid-base gas evolution reactions come under which type of reactions?

double displacment reaction

Intermolecular forces are all some kind of:

electrostatic attraction

Which intermolecular force is present in the condensed phases of all atoms and molecules?

london

Which among the following has the highest melting point?

methanol

Which of the following best explains what resonance structures are?

A molecule whose Lewis structure could be described by more than one resonance structure possesses an electronic structure equal to that of a combination of the resonance structures, with the more stable structures contributing more to the average structure.

If a compound's formula mass was experimentally determined to be 58, the chemical formula could be:

C3H6O

Identify the substance that does not show dipole-dipole interactions between molecules

CCl4

Which of the following would have the higher boiling point? co2 or CH3Cl

CH3Cl

Which molecule will NOT exhibit in hydrogen bonding between its molecules?

CH3OCH3

Which molecule will NOT exhibit resonance?

CO2

Which of the following is NOT weaker than a hydrogen bond?

COVALENT BOND

To convert moles of an atom to grams you must ______________ the molar mass.

multiply by

A base is something that: Select the correct answer below: gives up an H+ ion when dissolved in water produces an OH− ion when dissolved in water gains an OH− ion when dissolved in water none of the above

produces an OH− ion when dissolved in water

If there are multiple ways to place double bonds or lone pairs for a molecule, then a _________ can be created

resonace

Converting from moles of one compound into moles of another compound in a chemical equation will require the:

stoichiometric factors

The coefficients in a balanced chemical equation are used to derive:

stoichiometric factors

What kind of compound will generate the most hydroxide ions in solution?

strong base

In a chemical equation, the number of atoms of a particular element that are present in a formula unit or molecule of a compound is indicated by a:

subscript

The sum of the average atomic masses of all the atoms present in a substance's formula is known as

the formula mass (molecular mass)

If precipitation is not expected from a reaction, which of the following is indicated?

the products are soluble

Coefficients in a chemical formula provide:

the relative numbers of products and reactants

Compare 1 mole of hydrogen with 1 mole of oxygen. They will have:

the same number of atoms and different masses.

What is the coefficient for Al2O3 in the balanced version of the following chemical equation: Al2O3→Al+O2

2 First, write the unbalanced equation: Al2O3→Al+O2 To balance O, add a coefficient of 2 in front of Al2O3 and a coefficient of 3 in front of O2: 2 Al2O3→Al+3 O2 To balance Al, add a coefficient of 4 in front of Al: 2 Al2O3→4 Al+3 O2 The equation is now balanced. The coefficient in front of Al2O3 is 2.

How many moles of sulfur atoms are there in 64 g of S8?

2.0

What is the oxidation number for arsenic in the product of the following reaction: As+Cl2→AsCl3

+3

How many moles are in 22 grams of argon?

0.55

How many moles of sodium are in a 13.6 g block of sodium?

0.592 moles 13.6 grams × 1 mole / 22.990 grams=0.592 moles

The speed of light is around 6.706×108 miles per hour. What is the speed of light in units of miles per minute?

1.118 x 10(7)

Which of the following shows a correct arrangement of intermolecular forces from strongest to weakest?

hydrogen bonding > dipole-dipole interactions > London dispersion forces

The reactant that is almost entirely consumed in a reaction, thus limiting the amount of product generated, is known as

limiting reactant