Chem exam chapter 4

What is the oxidation number of iodine in I2?

0

Which equation describes a redox reaction?

2Al(s) + 3H2SO4(aq) → Al2(SO4)3(aq) + 3H2(g)

Which of these compounds is a strong electrolyte?

H2SO4

What is the reducing agent in the following reaction? Mg + NiO2 + 2H2O → Mg(OH)2 + Ni(OH)2

Mg

In the reaction 5H2O2 + 2MnO4- + 6H+ → 2Mn2+ + 8H2O + 5O2, what is the oxidizing agent?

MnO4-

Complete the following reaction and identify the Brønsted acid. NaOH(aq) + HCl(aq) →

NaCl(aq) + H2O(l); HCl is the acid.

In each of the following cases, write down the oxidation number of the indicated atom. a. P in P4 b. C in C2H6 c. S in H2SO4 d. Mn in MnO4- e. P in Na3PO4

a = 0, b = -3, c = +6, d = +7, e = +5

The substance HClO4 is considered to be

a strong acid

What is the oxidation number of N in N2H4?

-2

What is the oxidation number of oxygen in KMnO4?

-2

What is the oxidation number of N in K3Fe(CN)6?

-3

A 34.62-mL of 0.1510 M NaOH was needed to neutralize 50.0 mL of an H2SO4 solution. What is the concentration of the original sulfuric acid solution?

0.0523 M

Zinc dissolves in hydrochloric acid to yield hydrogen gas as follows: Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g) What mass of hydrogen gas is produced when a 7.35-g sample of zinc dissolves in 500.mL of 1.200 M HCl?

0.227g

35.0 mL of 0.255 M nitric acid is added to 45.0 mL of 0.328 M Mg(NO3)2. What is the concentration of nitrate ion in the final solution?

0.481M

How many moles of H+(aq) ions are present in 750 mL of 0.65 M hydrochloric acid?

0.49 mol

A standard solution of 0.243 M NaOH was used to determine the concentration of a hydrochloric acid solution. If 46.33 mL of NaOH is needed to neutralize 10.00 mL of the acid, what is the molar concentration of the acid in the original solution?

1.13M

Automobile batteries use 3.0 M H2SO4 as an electrolyte. How much 1.20 M NaOH will be needed to neutralize 225 mL of battery acid? H2SO4(aq) + 2NaOH(aq) → 2H2O(l) + Na2SO4(aq)

1.1L

What mass of lithium phosphate is needed to prepare 500. mL of a solution having a lithium ion concentration of 0.125 M?

2.41g

Which chemical equation describes a combustion reaction?

2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(l)

Which of these chemical equations describes a disproportionation reaction?

2H2O2(aq) → 2H2O(l) + O2(g)

Which of these chemical equations does not describe a redox reaction?

2LiOH(aq) + H2SO4(aq) → Li2SO4(aq) + 2H2O(l)

Vinegar is a solution of acetic acid, HC2H3O2 , dissolved in water. A 5.54-g sample of vinegar was neutralized by 30.10 mL of 0.100 M NaOH. What is the percent by weight of acetic acid in the vinegar?

3.26%

How many sodium ions are present in 325 mL of 0.850 M Na2SO4?

3.33 × 1023 Na ions

Starting with a 1.35 M HCl stock solution, five standard solutions are prepared by sequentially diluting 5.00 mL of each solution to 100.0 mL. What is the concentration of the final solution?

4.22 × 10-7 M

What volume of a 0.442 M NaOH solution is needed to neutralize 65.0 mL of a 0.296 M solution of HNO3?

43.5mL

Balance the following oxidation-reduction equation: Li(s) + O2(g) → Li2O(s)

4Li(s) + O2(g) → 2Li2O(s)

What volume of water must be added to 300 mL of 0.75 M HCl to dilute the solution to 0.25 M?

600 mL

A 0.8838-g sample of an ionic compound containing bromide ions and an unknown metal cation is dissolved in water and treated with an excess of AgNO3. If 1.573 g of a AgBr precipitate forms, what is the percent by mass of Br in the original compound?

75.72%

A 3.682-g sample of KClO3 is dissolved in enough water to give 375. mL of solution. What is the chlorate ion concentration in this solution?

8.01 ×10-2 M

Write a short definition for a Brønsted base.

A Brønsted base is a proton acceptor.

Which is the correct description of a solution?

A solution is a heterogeneous mixture of two or more substances. A solution is any mixture of two or more substances.

Based on the solubility rules, which one of these compounds is insoluble in water?

AgBr

Identify the element being oxidized in the following reaction. 4Al + 3O2 → 2Al2O3

Al or aluminum

Which statement is false concerning oxidation numbers?

An element's oxidation number is constant and unchanging.

If aqueous solutions of Ba(OH)2 and HNO3 are mixed, what products are formed?

Ba(NO3)2(aq) + H2O(l)

What is the net ionic equation if sodium sulfate is mixed with barium hydroxide?

Ba2+(aq) + SO42- (aq) → BaSO4(s)

Based on the solubility rules, which of these processes will occur if solutions of CuSO4(aq) and BaCl2(aq) are mixed?

BaSO4 will precipitate; Cu2+ and Cl- are spectator ions.

Which of these compounds is a nonelectrolyte?

C2H6O (ethanol)

Which of these compounds is a weak electrolyte?

CH3COOH (acetic acid)

Which salt is produced by the neutralization of nitric acid with calcium hydroxide?

Ca(NO3)2

Which of the following is a strong base?

Ca(OH)2

Which of these chemical equations describes a precipitation reaction?

CaBr2(aq) + H2SO4(aq) → CaSO4(s) + 2HBr(g)

Which salt is formed in the neutralization reaction of hydrochloric acid with calcium hydroxide?

CaCl2

Identify the reducing agent in the chemical reaction Cd + NiO2 + 2H2O → Cd(OH)2 + Ni(OH)2

Cd

What is reduced in the following reaction? Cu(NO3)2 + Zn → Zn(NO3)2 + Cu

Cu(NO3)2

Ammonium carbonate is not water soluble.

FALSE

H3PO4 is a strong acid.

FALSE

Hydration is the process in which organic solvent molecules surround a solute particle.

FALSE

Phenolphthalein is a universal indicator and maybe used as an indicator for all acid-base titrations.

FALSE

What is oxidized in the following reaction? Fe + Ag2O → FeO + 2Ag

Fe

________________ ____________ is a highly accurate analytical technique which is quantitative and based on the measurement of mass.

Gravimetric analysis

Which is present in all aqueous Brønsted acid solutions?

H+

Which of the following equations is not a redox reaction?

H2O(l) + NH3(g) → NH4+(aq) + OH-(aq)

Which one of the following substances is the strongest electrolyte?

HCL

Which of the following is a weak acid?

HF

Which of the following is a strong acid?

HNO3

H3O+ is called the ________________ ________________.

Hydronium ion

Identify the major ions present in an aqueous LiOH solution.

Li+, OH-

Which chemical equation describes an acid-base neutralization reaction?

LiOH(aq) + HNO3(aq) → LiNO3(aq) + H2O(l)

If aqueous solutions of Mg(C2H3O2)2 and LiOH are mixed, which insoluble precipitate is formed?

Mg(OH)2

What is the oxidizing agent in the following reaction? 5Fe2+(aq) + MnO4-(aq) + 8H+(aq) → 5Fe3+(aq) + Mn2+(aq) + 4H2O(l)

MnO4-

___________ is a concentration unit that is defined as the number of moles of solute per liters of solution.

Molarity

Based on the solubility rules, which one of these compounds is soluble in water?

Na2S

Select the compound in which sulfur has its highest possible oxidation number.

Na2SO4

Which accurately characterizes all nonelectrolyte solutions?

Nonelectrolyte solutions do not conduct electricity.

Which of the following is insoluble in water?

PbCl2

If aqueous solutions of lead(II) nitrate and sodium sulfate, which insoluble precipitate is formed?

PbSO4

The oxidation number for a pure element is always zero.

TRUE

The substance NH3 is considered to be

a weak base

The ______________ ______________ is the point in the titration where the moles of base added is equal to the moles of acid.

equivalance point

OH‾ is called the ____________________ ___________________.

hyrdroxide ion

A(n) _______________________ reaction is a reaction between an acid and a base which produces water and a salt consisting of cations from the base and anions from the acid.

neutralization

If aqueous solutions of KMnO4, FeSO4 and H2SO4, are mixed, which ions are spectator ions? 2KMnO4(aq) + 10FeSO4(aq) + 8H2SO4(aq) → K2SO4(aq) + 2MnSO4(aq) + 5Fe2(SO4)3(aq) + 8H2O(l)

only K+ and SO42-

Which is defined as the maximum amount of solute that will dissolve in a given quantity of solvent at a specific temperature?

solubility

Which substance is present in the smallest proportion in a solution?

solute