CH 4 HW Review

According to the following reaction, if 69g of KClO3 decomposes, how many grams of oxygen will form: 2KClO3→2KCl+3O2 Your answer should have two significant figures.

27 g

What is occurring in the following reaction: NaBr+Cl2→NaCl+Br2 Select the correct answer below: sodium is oxidized chlorine is oxidized bromine is reduced chlorine is reduced

Chlorine is reduced

Given the following balanced redox reaction: 2KMnO4+16HCl→2KCl+2MnCl2+8H2O+5Cl2 What is the stoichiometric factor relating KMnO4 and MnCl2, representing the actual numbers of moles of each species that react and are produced according to the equation above? Select the correct answer below: 5KMnO42MnCl2 1KMnO41MnCl2 2KMnO42MnCl2 2KMnO41MnCl2

2KMnO42MnCl2

Hydrochloric acid dissolves solid aluminum hydroxide. What is the complete ionic equation of this reaction? Select the correct answer below: 3 HCl+Al(OH)3(s)→3 H2O(l)+AlCl3(aq) 3 H++3 Cl−+Al(OH)3(s)→3 H2O(l)+Al3++3Cl− 3 H++Al(OH)3(s)→3 H2O(l)+Al3+ none of the above

3 H++3 Cl−+Al(OH)3(s)→3 H2O(l)+Al3++3Cl−

For the following chemical equation: BaBr2(aq)+H2SO4(aq)→BaSO4(s)+2HBr(aq) which will NOT be involved in the net ionic equation? Select the correct answer below: Ba2+(aq) Br−(aq) SO2−4(aq) BaSO4(s)

Br-(aq)

The permanganate ion, MnO−4, is a strong oxidizing agent. Write and balance the half-reaction for the formation of Mn(s) from MnO−4 in the presence of an aqueous acid. Use e− to represent the formula of an electron. Do NOT include the state (phase) information. Do NOT write out coefficients that are equal to 1. Be sure to denote any charges as needed.

MnO-4 + 8H+ + 7e- -> Mn + 4H2O

According to the equation below, how many moles of PbO are required to generate 3.88×1023 nitrogen molecules? 3PbO+2NH3→3Pb+N2+3H2O Use 6.022×1023mol−1 for Avogadro's number. Your answer should have three significant figures.

1.93 mol

If one cup of pancake mix will yield 15 pancakes, how many cups of pancake mix will be required to yield 60 pancakes? Report your answer as a whole number without any decimal places.

4 cups

What is the equivalence point of the titration? Select the correct answer below: the point where the concentrations of the analyte and the titrant are equal the point where the volumes of the analyte and the titrant are equal the point where a noticeable change in appearance occurs the point at which the volume of the titrant solution required for complete reaction with the analyte has been added

the point at which the volume of the titrant solution required for complete reaction with the analyte has been added

Coefficients in a chemical formula provide: Select the correct answer below: the relative numbers of products and reactants the absolute number of products and reactants the number of reactants only the number of products only

the relative numbers of products and reactants

The end point in a titration of a 68mL sample of aqueous HCl was reached by the addition of 42mL of 0.82MNaOH titrant. The reaction proceeds as follows. HCl(aq)+NaOH(aq)→NaCl(aq)+H2O(l) What is the molar concentration ofHCl? Report your answer with two significant figures.

0.51 M

According to the reaction 4A+3B→2C, how many moles of A are needed to generate 5 moles of C?

10 mol

How many moles of oxygen ( O2) are necessary to react completely with 43.9 moles of aluminum according to the following equation: 4Al+3O2→2Al2O3 Your answer should have three significant figures.

32.9 mol

Which of the following shows the correct stoichiometric ratio of H2O to CaCO3? CaCN2+3H2O⟶CaCO3+2NH3 Select the correct answer below: 3:1 1:1 1:2 2:3

3:1

If 2.67 moles of fluorine and 1.11 moles of ammonia react according to the following equation, how many grams of HF will form? 5F2+2NH3→N2F4+6HF Your answer should have three significant figures. (Round your answer to first decimal place).

64.1 grams

Which of the following dissolves in water to yield hydronium ions? Select all that apply. Select all that apply: NaCl HBr HNO3 HI

HBr,HNO3, and HI are strong acids: each of these will donate an acidic proton to water to generate hydronium in solution. NaCl will also dissolve in water but has no acidic protons, and thus will produce no hydronium ions in solution.

Which of the following compounds is water soluble? Select the correct answer below: AgCl PbCl2 AgBr KBr

KBr Halides of silver and lead are insoluble, but potassium bromide is soluble.

An aqueous solution contains the following ions: Cl−, F−, HCO−3, Mg2+, and NH+4. Is a precipitate likely to form? If so, give the formula of the precipitate. Select the correct answer below: Mg(HCO3)2 MgF2 NH4F No precipitate will form.

MgF2 According to the solubility rules, fluorides of group 2 metal cations will form precipitates. Since magnesium is in group 2, an alkaline earth metal, MgF2, will precipitate in this solution.

In the eighteenth century, why was potassium carbonate added to vinegar samples? Select the correct answer below: to create a precipitate to determine the "strength" of vinegar in vinegar samples to create bubbles to study the different types of reactions

to determine the "strength" of vinegar in vinegar samples

The ratio of the coefficients of two substances in a chemical equation is called a: Select the correct answer below: stoichiometric factor concentration ratio mass factor reaction quotient

stoichiometric factor This ratio is called a stoichiometric factor, which is used to determine the relative amounts of substances that will be involved in a reaction.

Fill in the blanks with the coefficients of the balanced version of the following chemical equation: Na+HCl→H2+NaCl Every box should have a whole number. While common convention is to leave out the 1 since it is assumed, in this case please use it (e.g. 1X+1Y→ 2Z)

2Na + 2HCl -> 1H2 + 2NaCl

What is the percent yield of CO2 if a reaction starts with 91.3 g C3H6 and produces 87.0 g CO2? 2C3H6+9O2→6CO2+6H2O Select the correct answer below: 30.4% 87.5% 76.4% 74.8%

30.4%

Fill in the blank with the coefficient for CO2 in the balanced version of the following chemical equation: C4H10O+O2→CO2+H2O Your answer should be a whole number.

4

What is the coefficient for water molecules in the balanced version of the following redox reaction? Cr2O2−7+C2H4O→C2H4O2+Cr3+ Your answer should be a whole number without any decimal places.

4

What is the stoichiometric ratio of the following: 4FeS+7O2→2Fe2O3+4SO2 Select the correct answer below: 4 moles+2 moles→2 moles+2 moles 4 moles+7 moles→2 moles+4 moles 4 moles+7 moles→1 mole+4 moles 4 moles+7 moles→3 moles+4 moles

4 moles+7 moles→2 moles+4 moles The stoichiometric ratio is based on the coefficients of each compound. The ratio of coefficients here is 4+7→2+4.

Which of the following shows the correct stoichiometric ratio of Fe to Fe2O3? Select the correct answer below: 2:3 4:2 2:4 3:2

4:2 The correct stoichiometric ratio compares the quantities of Fe to Fe2O3 so the ratio is 4:2.

Write in the coefficients to balance the following reaciton: FeBr3+H2SO4→Fe2(SO4)3+HBr

6FEBr3 + 3H2SO4 -> Fe2(SO4)3 + 6 HBr

In the equation 4A+2B→3C, if 12 molecules of A react, how many molecules of C will we get? Report your answer as an integer (whole number) without any decimal places.

9 molecules 12 is three times the 4 listed as the coefficient for A, so we must also triple the coefficient on C to get the corresponding number of C molecules we might expect.

Determine the unknown products for the following acid-base reaction. Use coefficients to balance the reaction, do not include coefficients of 1. Do not include phase labels. H2SO4 + 2NaOH -> ___ + ___

H2SO4 + 2NaOH -> Na2SO4 +2H2O Reactions between Arrhenius acids and bases always produce H2O and an ionic compound. This kind of reaction can be alternatively viewed as a double-displacement reaction. The H+ from the acid and the hydroxide ion OH− from the base combine to yield H2O, while the remaining ions combine to form an ionic compound. Here, two Na+ ions combine with SO2−4 to yield Na2SO4. A coefficient of 2 is needed for water to balance the equation. Therefore, the chemical reaction is written as H2SO4+2NaOH⟶Na2SO4+2H2O

According to general stoichiometric calculations, which of the following depicts the step relating moles of a substance with the mass of that substance? Select the correct answer below: molarity density avogadro's number molar mass

Molar mass

The concentration of vinegar was once determined by the measuring the amount of potassium carbonate that had to be added for bubbling to stop. What is this type of procedure called? Select the correct answer below: acid-base titration precipitation titration redox titration complex titration

acid-base titration

Identify which of the following is soluble. Select the correct answer below: ammonium hydroxide rubidium hydroxide potassium sulfate all of the above

all of the above Group 1 metal cations (rubidium and potassium) and the ammonium ion are soluble.

When performing a titration, the substance of unknown concentration is called: Select the correct answer below: analyte titrant acid base

analyte

To assess the stoichiometry of a reaction, one must use the: Select the correct answer below: unbalanced chemical equation balanced chemical equation masses of the substances volumes of the substances

balanced chemical equation The coefficients in the balanced chemical equation tell us the stoichiometric ratios of the substances involved in the chemical equation.

Which of the following is used to determine stoichiometric factors? Select the correct answer below: coefficients in a balanced chemical equation coefficients in an unbalanced chemical equation total number of reactants in a chemical equation total number of products in a chemical equation

coefficients in a balanced chemical equation Stoichiometric factors are derived from the coefficients in a balanced chemical equation

The quantitative relationship between the amounts of substance consumed and produced by a reaction is known as: Select the correct answer below: calorimetry stoichiometry molarity entropy

stoichiometry The quantitative relationship between the amounts of substance consumed and produced by a reaction is known as stoichiometry.

Which of the following ions will form a precipitate with the lead (II) cation in solution? Select all that apply: Ag+ Cl− F− NO−3 SO2−4

Cl− F− SO2−4 According to the solubility rules, the lead (II) cation will form precipitates with the chloride ion, fluoride ion, and sulfate ion.

The substances on the left side of a chemical equation are called: reactants products coefficients subscripts

reactants

Given the fictitious chemical equation below: 1 tablespoon of dry tea+2 cups of water⟶ 2 cups of tea What is the appropriate stoichiometric factor relating the two "reactants"?

1 tbsp dry tea / 2 cups H2O

How many molecules of O2 are required to react with 3.6 mol H2? 2H2+O2⟶2H2O Use 6.022×1023mol−1 for Avogadro's number. Your answer should have two significant figures.

1.1x10^24

According to the following reaction, if five moles of oxygen were to react completely, how many moles of water would be produced? 2H2+O2→2H2O Report your answer as a whole number without any decimal places.

10 mol

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 Your answer should have three significant figures. (Round your answer to the first decimal place.)

10.9 grams

If the theoretical yield of a reaction is 100 grams, which value for actual yield is physically impossible? Select the correct answer below: 0 grams 50 grams 99.9 grams 110 grams

110

How many hydrogen ions will be in the balanced version of the following redox reaction: H3PO2+Cr2O2−7⟶H3PO4+Cr3+ Select the correct answer below: 8 12 16 20

16

If 4 eggs are required to make 1 cake, how many eggs are required to make 4 cakes? Report your answer as a whole number without any decimal places.

16 eggs

What mass of HCl is required to produce 38 g ZnCl2? Zn+2HCl⟶ZnCl2+H2 Your answer should have two significant figures.

20 g

Which of the following is NOT a step in balancing redox reactions in acidic media? Select the correct answer below: Add the balanced half-reactions together and simplify by removing species that appear on both sides of the equation. Multiply each half-reaction's coefficients by the largest possible integers to yield equal numbers of electrons in each. Balance all elements except oxygen and hydrogen.

Multiply each half-reaction's coefficients by the largest possible integers to yield equal numbers of electrons in each. The steps involved in balancing redox reactions are: Write the two half-reactions representing the redox process. Balance all elements except oxygen and hydrogen. Balance oxygen atoms by adding H2O molecules. Balance hydrogen atoms by adding H+ ions. Balance charge by adding electrons. If necessary, multiply each half-reaction's coefficients by the smallest possible integers to yield equal numbers of electrons in each. Add the balanced half-reactions together and simplify by removing species that appear on both sides of the equation. Finally, check to see that both the number of atoms and the total charges are balanced. Therefore, multiplying each half-reaction's coefficients by the largest possible integers to yield equal numbers of electrons in each is not a step used to balance redox reactions. Your answer: Add the balanced half-reactions together and simplify by removing species that appear on both sides of the equation.

In the reaction of 2Na(s)+Cl2(g)→2NaCl(s), which element undergoes oxidation? Select the correct answer below: Na(s) Cl(g) NaCl(s) None of the above

Na(s) In the reaction of 2Na(s)+Cl2(g)→2NaCl(s), sodium is oxidized, and chlorine undergoes reduction. Viewed from a more active perspective, sodium functions as a reducing agent (reductant), since it provides electrons to (or reduces) chlorine. Likewise, chlorine functions as an oxidizing agent (oxidant) as it effectively removes electrons from (oxidizes) sodium.

Determine how many electrons are either produced or consumed by completing and balancing the following half-reaction in either an acidic or a basic solution. Cl2(g)⟶ClO−2(aq) Select the correct answer below: Three electrons are consumed. Three electrons are produced. Six electrons are consumed. Six electrons are produced.

Six electrons are procuded

Identify the oxidizing agent in the following reaction: Cr++Sn4+→Cr3++Sn2+ Select the correct answer below: Cr+ Sn4+ Cr3+ Sn2+

Sn4+ Chromium is oxidized from +1 to +3, so it must be tin that caused the oxidation as it was reduced, hence Sn4+ is the oxidizing agent.

The substances on the right side of a chemical equation are called: Select the correct answer below: reactants products coefficients subscripts

The products are the compounds that are produced as the result of a chemical reaction.

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

25 molecules of Z

Which of the following shows the correct stoichiometric ratio of Fe2O3 to O2? 4Fe+3O2⟶2Fe2O3 Select the correct answer below: 2:4 3:2 4:2 2:3

2:3

The __________ of an atom or molecule __________ when it undergoes reduction. Select the correct answer below: oxidation number, increases oxidation number, decreases charge, increases charge, decreases

oxidation number, decreases

Substances on the same side of a chemical equation are separated by a: Select the correct answer below: coefficient forward arrow plus sign subscript

plus sign Substances that are on the same side of an equation are separated by plus signs, indicating that they are both reactants or products, but that they are distinct, separate substances.

The substances generated by the chemical reaction are known as: Select the correct answer below: products reactants coefficients none of the above

products The substances generated by the chemical reaction are known as products.