Chemistry practice problems

HBr + H2SO4 SO2 + Br2 + H2O Did O change oxidation number?

no

Which of the following statements is true of cations?

Cations undergo reduction at the proper electrode.

What is the required molarity of a Ba(OH)2 solution to prepare a 1.0 M OH⁻ solution?

0.5 M

Calculate the molarity of solution given the following information: 10.0 g of NaOH were dissolved in 500.0 mL of solution.

0.500 M

Determine the number of grams of NaCl necessary to make up 100 mL of a 0.10 M solution.

0.58 g

How many grams of CO are in 125 mL of a 0.25 M solution?

0.87g

Sulfuric acid dissolves in water as H2SO4 2 H+(aq) + SO2 -2(aq). Which of the following solutions of H2SO4 will conduct the most electricity?

2.0 M

Potassium fluoride (KF), a salt, has a molecular weight of 58.10 grams. How many grams would be needed to make 1.0 liter of 5.0 molar salt solution?

250 g

The molecular weight of CaCl2 is 110.98 g/mol. In order to make up 500.0 mL of a 0.500 M solution, you need:

27.7 g

The reaction 2Cu + O2 2CuO has long been called an oxidation-reaction. Copper also reacts with chlorine Cu + Cl2 CuCl2. In such a reaction:

Copper is also oxidized even though no oxygen is present.

Ba(OH)2 Ba+2 + 2 OH- (dissolved in solution). Which will NOT happen to the equilibrium of this solution as H+ ions are added?

The reaction will move to the left.

Using a value of Ksp = 1.8 x 10-2 for the reaction PbCl2 Pb+2(aq) + 2Cl -(aq). If the value of Ksp was determined to be only 1.2 x 10-2:

The solution is unsaturated.

Electricity is conducted through a solution containing an electrolyte by:

ions

Determine the molecular weight of Ca3(PO4)2.

301.18g

M M+ + e- The reaction represents ___.

oxidation

Assign oxidation numbers to each element in this compound. KMnO₄ K = Mn = O =

+1 +7 -2

Assign oxidation numbers to each element in this compound. NO N = O =

+2 -2

Assign oxidation numbers to each element in this compound. MnO₂ Mn = O =

+4 -2

HBr + H2SO4 = SO2 + Br2 + H2O What is the oxidation number of the oxidizing agent? What is the oxidation number of the reducing agent?

+6 -1

How many moles does 10.0 mg of CO represent?

0.000357 mol

Which solution of NaI would be most dissociated?

0.1M

How many moles of NaOH are needed to make a 1 M solution?

1 mole

In a solution with a pH of 4, the [OH-] is:

1 x 10-10

A solution with a pH of 11 has a [H+] of:

1 x 10-11

Determine the molecular weight for Mg(NO3)2.

148.33 g

Determine the molecular weight of H2O.

18.02g

Balance this chemical equation. A coefficient of "1" is understood. Choose option "blank" for the correct answer if the coefficient is "1." ___H2O2 → ___H2O + ___O2

2 2 blank

When one mole of sodium chloride dissociates in water, it produces:

2 moles of ions

N₂ + 3H₂ 2NH₃ How many molecules of H2 are in the reactants? How many nitrogen atoms are present? How many moles of NH3 are formed?

3 2 2

What volume of 0.1 M NaOH is required to neutralize 30 mL of 0.1 M HCl?

30 mL

The [H+] concentration of an acetic acid solution is 1 x 10-4 mol/L. Calculate the pH of the solution?

4

Calculate the number of molecules in 0.75 mole of CH4. ___ x 10²³ molecules

4.5 x 10²³ molecules

Calculate the mass in grams of 0.35 moles of CH4.

5.6g

Potassium fluoride (KF), a salt, has a molecular weight of 58.10 grams. How many grams would be needed to mix 1.0 liter of 0.10 M salt solution?

5.8g

A solution that is neutral has a pH of:

7

The molecular weight of H2SO4 is:

98.086 g/mole

Below are 5 sets of potential solutes for you to compare. Both members of each pair are very soluble in water. If you had equal molar concentrations of each solution, which member of each pair would theoretically be the better conductor of electricity?

CsCl, CaCl2: Calcium Chloride CaS, Li2S: Lithium Sulfide KBr, AlCl3: Aluminum Chloride AlCl3, MgC2: Aluminum Chloride KI, K2S: Potassium Sulfide

2 KClO3 2 KCl + 3O2 The number of atoms in the product is greater than the number of atoms in the reactant.

False

A base releases H+.

False

All chemicals which contain OH in the formula are bases.

False

An acid has OH- ions in its formula.

False

Chemical reactions forming ions do not balance electrically.

False

Covalent solutions are good conductors of electricity.

False

Either oxidation or reduction can take place independently in any particular reaction.

False

Ionic solutions are poor conductors of electricity.

False

It is likely that Si and P would substitute for each other in a solid solution.

False

Molarity is represented by the symbol m.

False

Molecules are charged.

False

Solid solutions are rare.

False

Select all the species that are ions.

NH4+ H2PO4- H3O+

Select the compound in which chlorine is assigned the oxidation number +5.

NaClO3

Which of the following would be expected to form ionic solutions in water?

Nal

Which member(s) of the following list are ions?

PO4-3 HCO3- Al+3 Hg2+2

HBr + H2SO4 SO2 + Br2 + H2O Oxidizing agent = ___ Reducing agent = ___

S Br

Our body solution tests at a pH of about 6.8. This pH is:

Strongly acidic

If solid NaCl is added to a saturated water solution of PbCl2 at 20o C, a precipitate is formed. How would this affect the value of the Ksp for [Pb2+][Cl-] in solution?

The Ksp remains the same.

A homogeneous portion of a mixture that is characterized by uniform properties and capable of being separated by mechanical means is called a phase.

True

A solution is a homogeneous mixture.

True

Balanced equations illustrate Conservation of Mass.

True

Ions are charged atoms or groups of atoms.

True

Ions can consist of more than one atom.

True

Polar substances will usually dissolve in polar solvents.

True

Precipitation occurs when the product of the ion concentrations exceeds the Ksp.

True

Salt acts as an antifreeze.

True

The concentration of the particles in the solid phase always remains the same regardless of how much is present.

True

Titration is a process of reacting an acid with a base until an equivalence point is reached.

True

What relationship seems to be true?

When ionic character decreases, electrical conductivity decreases.

The Ksp expression for the system PbCl2(s) Pb+2(aq) + 2 Cl- is:

[Pb+2][Cl-]2

An acid is:

a proton donor

metal oxide + ___ salt + water

acid

What is the general word equation for salt formation by neutralization?

acid + base

Balance the reaction. A coefficient of "1" is understood. Choose option "blank" for the correct answer if the coefficient is "1." ___Pb(NO₃)₂ +___NaI → ___PbI₂ + )___NaNO₃

blank 2 blank 2

Balance the reaction. A coefficient of "1" is understood. Choose option "blank" for the correct answer if the coefficient is "1." 2AgNO3 + ___MgCl2 = 2AgCl + ___Mg(NO3)2

blank blank

Generally, you may expect ionization to be greater in:

dilute solutions

Electrolytes are defined as those compounds which:

dissolve in a solvent such as water to produce a solution which conducts electric current easily

As the concentration of a given salt solution increases, the conductivity of the solution:

increases

M M+ + e- Has M lost or gained an electron?

lost

2HBr + H2SO4 SO2 + Br2 + 2H2O Did H change oxidation number?

no

M M+ + e- Is M oxidized or reduced?

oxidized

Cu + H2O CuO + H2 This equation shows that Cu is ___. This equation shows that H2 is ___.

oxidized reduced

A solution of calcium chloride, CaCl2, will lower the freezing point of water to a greater extent than an equal concentration of NaCl because the solution of calcium chloride:

produces more ions

M M+ + e- Is M an oxidizing or reducing agent?

reducing

A characteristic of acids is that they react with metals to:

release hydrogen gas

If a crystal of KNO3 is added to a saturated water solution of KNO3 at 20°C, the added crystal will ___.

remain apparently unchanged.

One mole of ANY element contains the:

same number of atoms as one mole of any other element

Which of the following choices is not a factor in the amount of electrical conductivity of a solution?

size of container

The liquid component that makes up the largest part of a solution is called the ___ , and the substance that is dissolved is called the ___.

solvent solute

Which of the following choices would be a nonconducting substance or solution? (More than one may be correct.)

sucrose C12H22O11 (dissolved in water) distilled water

When is Ksp determined for a system? (Select all that apply.)

when equilibrium is established when the two phase system is saturated

HBr + H2SO4 SO2 + Br2 + H2O Did Br change oxidation number?

yes

HBr + H2SO4 SO2 + Br2 + H2O Did S change oxidation number?

yes