Chemistry 101: Exam II Review

Calculate the molarity of a solution prepared by dissolving 11.7 g of HCl in enough water to make 3.60 L of solution

0.0891 M

Consider the reaction represented by the (unbalanced) equation: N2(g) + H2(g)→NH3(g) Determine the number of moles of NH3(g) that can be produced from the following: 0.84 mol H2(g) reacts completely with N2(g)

0.56 mol NH3

How many moles of KClO3 are needed to produce 1081 L of O2 according to the equation: 2KClO3(s) → 2KCl(s) + 3O2(g) (The density of oxygen gas is 1.331 g/L.)

29.98 mol KClO3

What is the net ionic equation when aqueous sodium chloride is mixed with aqueous silver nitrate?

Ag+(aq) + Cl−(aq) → AgCl(s)

3.50×10-3 mol Ba(NO3)2 is dissolved in 265 mL of 0.0100 M K2CrO4. What precipitate forms in this reaction?

BaCrO4

Use the solubility rules in Table 7.1 to determine which of the following compounds is generally considered insoluble. KCl Al(NO3)3 BaSO4 LiCO3 (NH4)2S

BaSO4

What is the correct unbalanced equation for the reaction of solid magnesium metal with liquid water to form solid magnesium hydroxide and hydrogen gas?

Mg(s) + H2O(l) → Mg(OH)2(s) + H2(g)

Your textbook gives five steps for solving stoichiometry problems involving solutions. Order the following five steps correctly

Write the balanced equation for the reaction. For reactions involving ions, it is best to write the net ionic equation Calculate the moles of reactants Determine which reactant is limiting Calculate the moles of other reactants or products, as required Convert to grams or other units, if required

do the following form a precipitate when reacted together? K2CO3 and Na3PO4

no

do the following form a precipitate when reacted together? Na2SO4 and (NH4)2S

no

ammonium chromate solution is mixed with a barium nitrate solution what is the balanced molecular equation that represents this reaction What is the name of the precipitate what is the complete ionic equation what is the net ionic equation

(NH4)2CrO4 (aq) + Ba(NO3)2(aq) → BaCrO4(s) + 2NH4NO3(aq) barium chromate 2NH4+(aq) + CrO4 2-(aq) + Ba2+(aq) + 2NO3-(aq) → 2NH4+(aq) + 2NO3-(aq) + BaCrO4(s) CrO4 2-(aq) + Ba2+(aq) → BaCrO4(s)

What are the conditions at Standard Temperature and Pressure (STP)?

0 °C and 1 atm

You have a stock solution of 12 M HCl. How much of this stock solution should you take to prepare 0.75 L of 0.25 M HCl?

0.016 L (16 mL)

How many moles of Na+ ions are present in 24 mL of a 0.495 M Na2SO4 solution?

0.024 mol

You react 100.0 mL of 0.100 M lead(II) nitrate with 200.0 mL of 0.250 M potassium iodide. What is the concentration of I− ions left in solution after the reaction is complete?

0.100 M

N2(g) + 3H2(g) → 2NH3(g) 5.00 g N2 is reacted with 5.00 g H2 How many moles of N2 and H2 are there before the reaction? What is the limiting reactant in this reaction? How many mol NH3 can be produced in this reaction?

0.178 mol N2 and 2.48 mol H2 N2 0.356 mol NH3 How much reactant is leftover after the reaction? 1.95 mol H2

What are the concentrations of all the ions in a solution of 0.42 M Zn(NO3)2?

0.42 M Zn2+ and 0.84 M NO3−

What is the concentration of a 2.5 L solution containing 1.3 mol NaCl?

0.52 M

12.3 mL of a 0.341 M sodium phosphate solution reacts with 17.3 mL of a 0.160 M lead(II) nitrate solution. What mass of precipitate will form?

0.7490 g

Consider the following chemical equation: N2 + 3H2 → 2NH3 If 1.7 mol of H2 is reacted with excess N2, how many mol NH3 are formed?

1.1 mol NH3

Consider the reaction represented by the (unbalanced) equation: N2(g) + H2(g)→NH3(g) Determine the number of moles of NH3(g) that can be produced from the following: 0.56 mol N2(g) reacts completely with H2(g)

1.1 mol NH3

Determine the sum of the coefficients for the equation when balanced in standard form Fe + H2O→Fe3O4 + H2

12

Hydrogen sulfide gas gives rotten eggs their terrible odor. Hydrogen sulfide burns in air (O2) to produce sulfur dioxide gas and water vapor. If 9.25 moles of sulfur dioxide are produced when this reaction occurs, how many moles of oxygen were required?

13.9 mol oxygen required

Consider the following unbalanced reaction: C(s) + S8(s) → CS2(l) How many grams of carbon disulfide will be produced if 5.70 g of C and 12.1 g of S8 are allowed to react completely?

14.4 g CS2

Consider the following chemical equation: N2 + 3H2 → 2NH3 If 3.0 g of hydrogen is reacted with excess nitrogen, how many grams of ammonia are formed?

17 g NH3

Consider the following chemical equation: N2 + 3H2 → 2NH3 If 3 mol of hydrogen is reacted with 3 mol of nitrogen, how many moles of ammonia are formed?

2 mol NH3 because there are 3 mol of H2 which is the limiting reactant

You add 250.0 mL of water to 250.0 mL of a 4.00 M sugar solution. Calculate the concentration of the new solution in units of molarity

2.00 M

Consider the following reaction: Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g) If 2.25 g of solid magnesium reacts with 100.0 mL of 3.00 M hydrochloric acid, what volume of hydrogen gas is produced at 23°C and 1.00 atm?

2.26 L

What is the volume of 1.00 mol of gas at STP (assume, as usual, that the gas is behaving ideally)?

22.4 L

For the following unbalanced reaction at 1.00 atm and 24.0°C: MoS2(s) + O2(g) → MoO3(s) + SO2(g) What volume of oxygen gas (in L) would be needed to react with 47.1 g of MoS2?

25.11 L oxygen

How many grams of formaldehyde are in 104.1 mL of a 12.4 M aqueous solution of formaldehyde (formalin)? The formula for formaldehyde is HCHO

38.7 g

Consider the following unbalanced combustion reaction: C2H2 + O2 → CO2 + H2O How many moles of oxygen would be required to react with 1.96 moles of acetylene (C2H2)?

4.90 mol oxygen

Consider the unbalanced reaction between silver nitrate and sodium chromate: AgNO3(aq) + Na2CrO4(aq) → Ag2CrO4(s) + NaNO3(aq) What mass of silver chromate (in grams) will be produced when 100.0 mL of 2.70 M silver nitrate is mixed with 300.0 mL of 1.40 M sodium chromate? what is the concentration of the sodium, nitrate, silver, and chromate ions left in solution after the reaction is complete

44.8 g silver chromate 2.10 M 0.675 M 0.712 M

Consider the following reaction: 2Mg(s) + CO2(g) → 2MgO(s) + C(s) You react 5.00 g Mg with 10.0 g CO2. What is the mass of the leftover reactant after the reaction is complete?

5.47 g

Determine the sum of the coefficients for the equation when balanced in standard form Na2S2O3 + I2→Na2S4O6 + NaI

6

Consider the reaction represented by the (unbalanced) equation: NH3 + O2→NO + H2O For every 5.00 mol of NH3 that reacts, how many mol of O2 is required

6.25 mol of O2 is required

Calculate the volume of hydrogen produced at 1.50 atm and 19 oC by the reaction of 26.5 g of zinc with excess hydrochloric acid according to the balanced equation: Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)

6.47 L

Methyl alcohol (CH3OH) is made by reacting carbon monoxide and hydrogen in the presence of certain metal catalysts. CO + 2H2 → CH3OH How much alcohol (in grams) can be obtained by reacting 54.2 g of CO with 14.4 g of H2? How many grams of excess reactant remain unreacted?

62.0 g CH3OH 6.60 g excess reactant

Determine the sum of the coefficients for the equation when balanced in standard form NO + H2→N2 + H2O

7

The reaction between silver nitrate and sodium chromate forms a solid. What is the correct formula for this precipitate?

Ag2CrO4

What does a chemist mean when he or she says an acid has been neutralized?

An exact (stoichiometric) amount of base has reacted with the acid

Which of the following chemical equations is balanced? Na + Cl2 → NaCl C2H4 + O2 → 2CO2 + 2H2O 2Mg + 3N2 → 2Mg2N3 Mg + 2H2O → Mg(OH)2 + 2H2 CH4 + 2O2 → CO2 + 2H2O

CH4 + 2O2 → CO2 + 2H2O

3.50×10-3 mol Ba(NO3)2 is dissolved in 265 mL of 0.0100 M K2CrO4. What is the limiting reactant?

CrO42−

Consider the following reaction: C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(g) Which of the statements below is true regarding this reaction equation When 1 g of C3H8 is reacted, 3 g of CO2 are created For every 5 mol of O2 reacted, 3 mol of CO2 are formed You have made 3 mol of CO2 and 4 mol of H2O CO2 is a reactant and C3H8 is a product You have 1 molecule of C3H8 and it is reacting with 5 molecules of O2

For every 5 mol of O2 reacted, 3 mol of CO2 are formed

Consider the following complete ionic equation: 2K+(aq) + CrO42−(aq) + Ba2+(aq) + 2NO3−(aq) → BaCrO4(s) + 2K+(aq) + 2NO3−(aq) What are the spectator ions in this reaction?

K+ and NO3−

When ionic compounds dissolve, the resulting solution contains the separated ions. What types of ions are present in the solution when K2CrO4(aq) and Ba(NO3)2(aq) are mixed?

K+, CrO42−, Ba2+, NO3−

A solution of magnesium chloride (MgCl2) is mixed with a solution of silver nitrate (AgNO3), and a solid (precipitate) forms. What are the possible formulas for the solid?

Mg(NO3)2 and AgCl

magnesium bromide solution is mixed with a lead(II) nitrate solution what is the balanced molecular equation that represents this reaction What is the name of the precipitate what is the complete ionic equation what is the net ionic equation

MgBr2(aq) + Pb(NO3)2(aq) → Mg(NO3)2(aq) + PbBr2(s) lead(II) bromide Mg2+(aq) + 2Br-(aq) + Pb2+(aq) + 2NO3-(aq) → Mg2+(aq) + 2NO3-(aq) + PbBr2(s) Pb2+(aq) + 2Br-(aq) → PbBr2(s)

Calculate the molarity of a solution in which enough water is added to 286.5 g of magnesium bromide to make a solution with a volume of 1.62 L

Molarity = 0.961 M

Which of the following is not a strong acid? NaOH HCl H2SO4 HNO3

NaOH

Which of the following is a clue that a chemical reaction has taken place? - bubbles form - solid forms - flame is produced

all of the above

What should be adjusted to properly balance a chemical equation?

coeficients

True or False: A saturated solution is one in which more solute can be dissolved

false

There are several "driving forces" that pull reactants toward products - changes that tend to make reactions go in the direction of the arrow. A common driving force includes

formation of a gas transfer of electrons formation of water formation of a solid

do the following form a precipitate when reacted together? AgNO3 and Pb(NO3)2

no

do the following form a precipitate when reacted together? Fe(NO3)2 and BaCl2

no

do the following form a precipitate when reacted together? Fe(NO3)2 and Pb(NO3)2

no

do the following form a precipitate when reacted together? K2CO3 and (NH4)2S

no

do the following form a precipitate when reacted together? Na2SO4 and Na3PO4

no

True or False: A solution which contains a relatively large amount of solute is considered concentrated

true

True or False: A solution which contains a relatively small amount of solute is considered dilute

true

True or False: For solubility in general, like dissolves like

true

True or False: When ionic compounds dissolve in water, they break up (dissociate) into individual cations and anions

true

What is always formed when a strong acid solution reacts with a strong base solution?

water (H2O)

do the following form a precipitate when reacted together? AgNO3 and (NH4)2S

yes; Ag2S

do the following form a precipitate when reacted together? AgNO3 and Na3PO4

yes; Ag3PO4

do the following form a precipitate when reacted together? AgNO3 and BaCl2

yes; AgCl

do the following form a precipitate when reacted together? K2CO3 and BaCl2

yes; BaCO3

do the following form a precipitate when reacted together? Na2SO4 and BaCl2

yes; BaSO4

do the following form a precipitate when reacted together? Fe(NO3)2 and Na3PO4

yes; Fe3(PO4)2

do the following form a precipitate when reacted together? Fe(NO3)2 and (NH4)2S

yes; FeS

do the following form a precipitate when reacted together? K2CO3 and Pb(NO3)2

yes; PbCO3

do the following form a precipitate when reacted together? Na2SO4 and Pb(NO3)2

yes; PbSO4