Question 1

Write down the oxidation number of the indicated atom in each of the following formulas: a. Si in SiO₂ b. Cl in ClO₂^- c. Mn in KMnO₄ d. C in C₆H₁₂O₆

Accepted Answer

The answer of Write down the oxidation number of the...

Question 2

Aluminum metal dissolved in hydrochloric acid as follows: 2Al(s) + 6HCl(aq) $\to$ 2AlCl₃(aq) + 3H₂(g) a. What is the minimum volume of 6.0 M HCl(aq) needed to completely dissolve 3.20 g of aluminum in this reaction? b. What mass of AlCl₃would be produced by complete reaction of 3.20 g of aluminum?

Accepted Answer

The answer of Aluminum metal dissolved in hydrochloric acid as...

Question 3

In an acid-base (neutralization) reaction the equivalence point is the point where the indicator changes color.

Accepted Answer

The equivalence point in an acid-base reaction is the point at which the amount of acid equals the amount of base in moles, not necessarily the point where the indicator changes color. The indicator's color change point can vary depending on its pH range and may not exactly match the equivalence point.

Question 4

a. Define "oxidation". b. Identify the oxidizing and reducing agents in the following (unbalanced) equation. HNO₃(aq) + C₂H₆O(aq) + K₂Cr₂O₇(aq) $\to$ KNO₃(aq) + C₂H₄O(aq) + H₂O(l) + Cr(NO₃)₃(aq)

Accepted Answer

The answer of a. Define "oxidation".
b. Identify the oxidizing and...

Question 5

You are provided with a 250 mL volumetric flask, deionized water, and solid NaOH. How much NaOH should be weighed out in order to make 250. mL of 0.100 M solution?

Accepted Answer

The answer of You are provided with a 250 mL...

Question 6

In an acid-base (neutralization) reaction the indicator will change color at the end point.

Accepted Answer

An indicator is used to detect the endpoint of an acid-base neutralization reaction, and it changes color when the reaction has reached completion.

Question 7

Covalent compounds, dissolved in water, never produce conducting solutions.

Accepted Answer

Dissolving covalent compounds in water can produce conducting solutions if they ionize or dissociate into ions in solution. Examples include acids (such as HCl or acetic acid) and some polar covalent compounds (such as ammonia). However, non-polar covalent compounds (such as methane) will not dissociate into ions and will not form conducting solutions.

Question 8

When a solution is diluted with water, the ratio of the initial to final volumes of solution is equal to the ratio of final to initial molarities.

Accepted Answer

This statement is known as the dilution equation, which is expressed as M1V1 = M2V2, where M1 and V1 are the initial concentration and volume, and M2 and V2 are the final concentration and volume. It can also be written as the ratio of initial to final molarities being equal to the ratio of final to initial volumes, as stated in the question.

Question 9

All acid-base reactions produce a salt and water as the only products.

Accepted Answer

Not all acid-base reactions produce a salt and water; some produce other products depending on the reactants involved. For example, reactions involving weak acids or bases can produce different products, and gas formation reactions are also common in acid-base chemistry.

Question 10

a. A solution of common salt, NaCl, in water has a concentration of 0.0921 M. Calculate the number of moles of NaCl contained in 50.0 mL of this solution.
b. If, instead, an NaCl solution is prepared by dissolving 10.0 g of solid NaCl in enough water to make 250. mL of solution, what is the molarity?

Accepted Answer

The answer of a. A solution of common salt, NaCl,...

Question 11

In a redox reaction, the reducing agent undergoes loss of electrons.

Accepted Answer

In a redox reaction, the reducing agent gives away electrons (is oxidized) and the oxidizing agent accepts electrons (is reduced). Therefore, the reducing agent undergoes loss of electrons.

Question 12

Some covalent compounds dissolve in water to produce conducting solutions.

Accepted Answer

Some covalent compounds, such as hydrogen chloride (HCl) and hydrogen iodide (HI), ionize in water to produce conducting solutions. These solutions contain ions that can conduct electricity, unlike pure covalent compounds, which do not conduct electricity.

Question 13

The correct method for preparing one liter of a 1.0 M solution of X is to dissolve exactly one mole of X in exactly one liter of water.

Accepted Answer

The correct method is to dissolve one mole of X in enough water to make the total solution volume one liter, not to add it to exactly one liter of water.

Question 14

For each of the following species, write down, next to the formula, the oxidation number of the indicated atom. a. P in H₂PO₂^- b. S in Na₂S₂O₃ c. C in CH₂O

Accepted Answer

The answer of For each of the following species, write...

Question 15

Oxidation is associated with an increase in oxidation number.

Accepted Answer

This is because oxidation involves the loss of electrons, which in turn leads to an increase in oxidation number.

Question 16

a. Explain or define what is meant by the term "oxidation." b. Write down the oxidation numbers of all the atoms in the following formulas. K₂Cr₂O₇NaH

Accepted Answer

The answer of a. Explain or define what is meant...

Question 17

A solution of methanol (CH₄O) in water has a concentration of 0.200 M. What mass of methanol, in grams, is present in 0.150 liters of this solution?

Accepted Answer

The answer of A solution of methanol (CH₄O) in water...

Question 18

Reduction is the loss of electrons.

Accepted Answer

Reduction is the gain of electrons, while oxidation is the loss of electrons.

Question 19

In a redox reaction, the oxidizing agent undergoes loss of electrons.

Accepted Answer

In a redox reaction, the oxidizing agent gains electrons and is reduced, while the reducing agent loses electrons and is oxidized.

Question 20

A particular reaction may be both a precipitation and an acid-base (neutralization) reaction.

Accepted Answer

This is possible if a salt is formed as a precipitate and an acid or a base is neutralized in the process. For example, the reaction between sodium hydroxide and hydrochloric acid results in the formation of sodium chloride, which precipitates as a solid, and water. This reaction is both a precipitation and an acid-base reaction.

Quiz 4: The Major Classes of Chemical Reactions

Write down the oxidation number of the indicated atom in each of the following formulas: a. Si in SiO2 b. Cl in ClO2- c. Mn in KMnO4 d. C in C6H12O6