CHEM 1114 Lecture Notes - Amphoterism, Sodium Chloride, Nonmetal

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23 Mar 2013

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Salts form when a positive metal ion from the base combines with a negative non-metal ion from the acid (nacl is formed between naoh and hcl) Salt solutions can be acidic, basic or neutral (ions from the salt may react with water to produce h3o , oh- or neither) So4 (has no effect on the nature of solutions) Fe3+ = fe(h2o)6 3+ ; al3+ = al(h2o)6 3+ * = ions that exist as hexahydrates in solutions. No hydrolysis and salt solution is neutral (ph=7) Hydrolysis of the anion, producing oh- aka anionic hydrolysis.

Related Questions

The nitrate ion, NO3-, is in a separate group from the anions used in todayâs experiment. The groups are listed below. Suggest a reason why the procedure used today would make the determination of the nitrate ion difficult.

1. Group I: the sulfate group. This group is named the same as the sulfate ion but it also contains other âate ions, like carbonate (CO₃^2â) and phosphate (PO₄^3â). These anions selectively react with Ba²⁺ cation (or other alkaline earth metal cations like Ca²⁺) under basic conditions (eg. ammonia solution) and generate precipitations. The reaction can be either reversible or irreversible depends on the chemical property of the precipitation.

2. Group II: the halide group. This group includes or the halides and sulfide (S^2â). These anions can react with Ag⁺ cation under acidic or neutral conditions. The reaction usually generates very insoluble and chemically stable precipitation.

3. Group III: the nitrate group. The nitrate (NO₃^â) anion forms water soluble salt with all the common cations.

a Safari allä»¤ 4:15 PM * 19% Laboratory Experiments 267 standardize knob until the pH meter indicates the exact pH of the buffer solution. Wait 5 s to be certain that the reading remains constant. Once you have standardized the pH meter, do not readjust the standardize knob. Turn the function knob to standby. Carefully lift the electrodes from the buffer and rinse them with distilled water. The pH meter is now ready to use to measure pH. 2. Effect of Acid and Base on the Buffer pH Pour half (32 mL) of the buffer solution you prepared above into another 150-mL beaker. Label the two beakers 1 and 2. (CAUTION: Concentrated HCL can cause severe burns. Avoid contact with it. If you come in contact with it, immediately wash the area with copious amounts of water.) Pipet 1.0 mL of 6.0 M HCl into beaker 1, mix, and then measure the pH of the re- sultant solution and record the pH. Remember to rinse the electrodes be- tween pH measurements. (CAUTION: Sodium hydroxide can cause severe burns. Avoid contact with it. If you come in contact with it, immediately wash the area with copious amounts of water.) Similarly, pipet 1.0 mL of 6.0 MNaOH into beaker 2, mix, and then measure and record the pH of the resultant solution. Calculate the pH values of the original buffer solution, the values after the additions of the HCl and NaOH. How do the measured and calculated values compare? Dispose of the chemicals in the designated receptacles. Before beginning this experiment in the laboratory, you should be able toan swer the following questions: PRE LAB QUESTIONS 1. Define BrÃ¸nsted-Lowry acids and bases. 2. Which of the following ions will react with water in a hydrolysis reac- tion: Nat, Ca2+, Cu2+,Zn2*,F, So,Br? For those ions in question 2 that undergo hydrolysis, write net ionic equations for the hydrolysis reaction. The Ka for HCN is 4.9 Ã 10-10 What is the value of Kb for CN-? 3. 4. 5. What are the conjugate base and conjugate acid of H2PO4? 6. From what acid and what base were the following salts made: CaSO4, NH Br, and BaCl2? 7. Define the term salt Tell whether 0.1 M solutions of the following salts would be acidic, neutral, or basic: BaCl2, CuSO4, (NH4) S04, ZnCl2, NaCN. If the pH of a solution is 8, what are the hydrogen- and hydroxide-ion 8. 9. concentrations? The pH of a 0.1 M MCI (M* is an unknown cation) was found to be 4.7 Write a net ionic equation for the hydrolysis of M and its correspond ing equilibrium expression Kp. Calculate the value of Kp What is the pH of a solution that is 0.10 M HC2H302 and 0.20 M NaC2H3O2? Ka for acetic acid 1.8 Ã 10-b 10. 11.

QUESTION 1

Which of the following substances is most acidic?

		Cowâs milk - pH 6.6
		Apple juice - pH 3.0
		Tomato juice - pH 4.5
		Distilled water - pH 7.0

2 points

QUESTION 2

A buffer is a substance that converts:

Alkaline solutions to neutral solutions.

Acidic solutions to alkaline solutions.

Strong bases or acids to weak bases or acids.

Acidic solutions to neutral solutions.

QUESTION 3

How does a solution of pH 7 compare to a solution of pH 10?

		pH 7 has more OH^- ions
		pH 7 is more basic
		pH 7 has a higher pH
		pH 7 has more H⁺ ions

2 points

QUESTION 4

According to the Arrhenius Theory of acids and bases, a base is:

A substance that decrease the amount of hydroxide ions present.

A substance that increases the amount of hydroxide ions present when it is dissolved in water.

A substance that increase the amount of hydrogen ions present.

A substance that increases the amount of hydrogen ions present when it is dissolved in water.

QUESTION 5

Which of the following are true regarding acid-base titrations?

		They are used to determine the concentration of an unknown acid or base.
		The acid or the base must be a standard solution with a known concentration
		The standard solution is titrated into the chemical with the unknown concentration.
		All of the above are true regarding acid-base titrations.

2 points

QUESTION 6

Which of the following is not an example of a neutralization reaction?

HCl + NaOH NaCl +H₂O

2 NaOH + H₂CO₃ Na₂CO₃ +2 H₂O

H₂SO₄ + 2 NH₄OH (NH₄)₂SO₄ + 2 H₂O

2 AgNO₃ + Zn 2Ag +Zn(NO₃)₂

QUESTION 7

Which acid base theory defines an acid as a proton donor and a base as a proton acceptor?

		Arrhenius Theory
		Bronsted-Lowery Theory
		Conjugate Pairs Theory
		Lewis Theory

2 points

QUESTION 8

The Arrhenius Theory states that acid-base reactions create a solution composed of a water and a salt. This is because mixing an acidic and basic solution together yields:

A neutral solution

A solution with a pH at or near 7

Both A and B are correct

QUESTION 9

Which of the following correctly defines a standard solution?

		A solution which always has the same molecular geometry.
		A solution in which the concentration is precisely known.
		A solution in which the volume is precisely known.
		A solution which always has different levels of solutes and solvents.

2 points

QUESTION 10

Acids naturally present in food are generally safe to eat because they are usually:

		Concentrated
		Dilute
		Weak
		Strong

None of the above are correct

CHEM 1114 Lecture Notes - Amphoterism, Sodium Chloride, Nonmetal

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