AP Chem Unit 4 Review

A student combines a solution of NaCl(aq) with a solution of AgNO3(aq), and a precipitate forms.

Which of the following is the balanced net ionic equation for the formation of the precipitate?

• Ag+(aq)+Cl−(aq)→AgCl(s)

• Na+(aq)+NO3−(aq)→NaNO3(s)

• NaCl(aq)+AgNO3(aq)→NaNO3(s)+AgCl(aq)

• NaCl(aq)+AgNO3(aq)→NaNO3(aq)+AgCl(s)

Tags

NGSS.HS-PS1-7

A chemistry teacher carried out several demonstrations, and students recorded their observations. For one of the demonstrations, a student concluded that a physical change took place, but not a chemical change. Which of the following observations could the student have made of the results of the demonstration?

• Two colorless solutions were combined, and the resulting solution was pink.

• When a solid was added to a liquid, sparks were produced.

• One piece of solid substance was changed into small pieces.

• When two solutions were combined, a precipitate formed.

Tags

NGSS.MS-PS1-2

Which of the following is the correct net ionic equation of the reaction that occurs when aqueous solutions of ammonia and hydrochloric acid are combined?

• NH3(aq)+HCl(aq)→NH4Cl(aq)

• NH3(aq)+H+(aq)→NH4+(aq)

• NH3(aq)+HCl(aq)→NH4+(aq)+Cl−(aq)

• NH3(aq)+H+(aq)+Cl−(aq)→NH4+(aq)+Cl−(aq)

Zn(s)+2HCl(aq)→ZnCl2(aq)+H2(g)

When the reaction represented above proceeds, heat is produced. Which of the following best describes the reaction?

• It is a combustion reaction because heat is produced by the reaction.

• It is a double replacement reaction because 2Cl atoms are added to Zn.

• It is an acid-base reaction because HCl is an acid that is capable of exchanging H+.

• It is an oxidation-reduction reaction because zinc is oxidized and hydrogen is reduced.

Answer explanation

Check the oxidation states of each atom. Combustion reactions have the reactant O2 and product H2O + CO2

Tags

NGSS.HS-PS1-4

In the reaction between C5H5N(aq) and HHCl(aq) represented above, C5H5N acts as

• a Brønsted-Lowry base

• a Brønsted-Lowry acid

• the conjugate base of HCl

• the conjugate acid of [C5H5NH]+

Answer explanation

B-L bases accept protons

A student combines a solution of NaCl(aq) with a solution of AgNO3(aq), and a precipitate forms.

Which of the following is evidence that ionic bonds formed during the precipitation?

• The resulting solution is colorless.

• The resulting solution conducts electricity.

• The precipitate has a high melting point.

• The temperature of the solution did not change significantly during the precipitation.

Tags

NGSS.HS-PS1-3

Zn(s)+CuSO4(aq)→Cu(s)+ZnSO4(aq)

When a zinc plate is placed in an aqueous solution of copper sulfate, elemental copper forms, as represented by the equation above. Which of the following represents the reduction half-reaction of the reaction? (Sulfate, SO4, has a -2 charge)

Answer explanation

Copper is being reduced and zinc is being oxidized. Reduction reactions always have the species gaining electro on the left side of the reaction arrow.

Tags

NGSS.HS-PS1-2

NGSS.HS-PS1-7

What is a titration?

• when the moles of hydrogen ions is equal to the moles of hydroxide ions

• adding a known amount of solution of known concentration to determine the concentration of an unknown

• reaction in which an acid and a base react in an aqueous solution to produce a salt and water

• the extent of ionization of an acid or base

In the reaction Zn + H₂O → ZnO₂ + H₂ which element is oxidized? 

• Zinc
• Hydrogen
• Oxygen
• None

Tags

NGSS.HS-PS1-4

A hydrogen ion, H⁺, is the same as a(n):

• neutron
• electron
• proton
• hydroxide ion