CHEM110L - Experiment 5, Acids, Bases, and Salts

In an aqueous solution, name and write the formula of the ion that makes a solution acidic

H3O+, hydronium ion

In an aqueous solution, name and write the formula of the ion that makes a solution basic

OH-, hydroxide ion

Muriatic acid is used to adjust the pH of swimming pools. What is the formula of muriatic acid? does the pH of the swimming pool increase or decrease as a result of adding muriatic acid? Explain.

Muriatic acid is HCl. Adding it to the swimming pool will cause the pH of the swimming pool to decrease because acids have a lower pH. This is because acids release H+(or H3O+) ions in water and the formula for pH is -log[H3O+], so the larger the concentration, the more negative the pH.

Battery acid is a rather concentrated solution of sulfuric acid. What is the formula of sulfuric acid

H2SO4

Aqueous salt solutions are often not neutral with respect to pH. Explain.

In an aqueous salt solution, the salt exists only as ions. Those ions have the tendency to attract other ions. Depending on which ion of the salt compound has the higher electron affinity, the ions will attract either H+ or OH- ions, shifting the concentration of H+ and affecting pH.

Milk of magnesia is used as a laxative and to treat upset stomachs. What is the formula of milk of magnesia?

Mg(OH)2

Washing soda is often added to detergent formulations to make the wash water more basic. What is the anhydrous form of washing soda? Does it increase or decrease the pH of wash water? Explain.

sodium carbonate, Na2CO3. Increases the pH of wash water because it is basic, and basic solutions release OH- ions that bond to any free H+ ions, driving the concentration of H+ down and thereby driving the pH up.

Three solutions have the following pH:

1: 7.4

2: 10.6

3: 3.7

a. which contains the highest H3O+ concentration?

b. which is the most acidic?

c. which is the most basic?

a. solution 3, with a pH of 3.7 has the highest H3O+ concentration because it is the most acidic. The lower the pH, the more acidic, and the higher the H3O+ concentration.

b. solution 3 is the most acidic because it has the lowest pH.

c. solution 2 is the most basic because it has the highest pH, and thus the lowest concentration of H3O+ ions.

Metallic ions with a higher positive charge are more strongly hydrated and tend to be more acidic in solution. Comparing a 0.12 M FeCl3 solution to a 0.12 M FeCl2 solution, which would have a lower pH?

The FeCl3 solution would have a lower pH because it has a higher positive charge (we know that Cl will always have a -1 charge), and is therefore more acidic. The more acidic, the lower the pH, so FeCl3 has the lower pH.

Nickel(II) chloride dissolves in water to form a light green solution. What ions are present in solution - that is, what is swimming around in the aqueous solution? Write the formulas

NiCl2 => Ni+2 + Cl-

sodium carbonate dissolves in water to form a colorless solution. What ions are in solution? Write the formulas

Na2CO3 => Na+ + (CO3)2-

when solutions of nickel(II) chloride and sodium carbonate are combined, a green nickel(II) carbonate precipitate forms. What is the formula of the precipitate?

NiCl2(aq) + Na2CO3(aq) => Ni2CO3(s) + 2NaCl(aq)

write the ionic equation representing the reactants as they exist in solution before the reaction and the products as they exist in solution after the reaction.

Ni+ + 2Cl- + 2Na+ + (CO3)2- => Ni2CO3(s) + 2Na+ + 2Cl-

What spectator ions remain in solution in the reaction between NiCl2 and Na2CO3

Cl- and Na+

Write the net ionic reaction that accounts for the appearance of the precipitates in the reaction between NiCl2 and Na2CO3

Ni2+(aq) + (CO3)2-(aq) => NiCO3(s)

The observation for the reaction of 6M HCl was obviously different from that of 6M CH3COOH. What were the contrasting observations. How do the two acids differ?

Although both reactions were apparent, the reaction of HCl was much stronger, dissolving the Mg metal completely and nearly dissolving the Zn metal, producing foam and a great deal of heat, whereas the reaction of CH3COOH was much less intense. This is because HCl is a stronger acid than CH3COOH.

As the molar concentration of an acid decreases, the reaction rate with an active metal, such as magnesium, is expected to ____. Explain.

Decrease. If fewer moles of acid are present to react with the metal, the number of atoms reacting with one another will decrease, so the intensity of the reaction will be less.

6 M H2SO4 is carelessly substituted for 6M HCl. Will more or fewer drops of 6M H2SO4 be required for the litmus to change color? Explain.

It would take more drops of H2SO4 for the litmus to change color because H2SO4 is a weaker acid than HCl. This means that it is slightly less likely to ionize and react with NaOH.

Write a net ionic equation for the reaction of hydrochloric acid with sodium hydroxide

write ionic equation:

H+ + Cl- + Na+ + OH- => H2O(l) + Na+ + Cl-

remove spectator ions:

H + + OH- => H2O(l)

Sodium carbonate dissolved in water produces a basic solution. water soluble potassium phosphate K3PO4, also produces a basic solution. Write an equation that accounts for the basicity of K3PO4.

K3PO4 + H2O => KOH + H3PO4

The setting of mortar is a time-consuming process that involves a chemical reaction of quicklime, CaO, with carbon dioxide and water of the atmosphere, forming CaCO3 and Ca(OH)2 respectively. Write the two balanced equations that represent the setting of mortar.

CaO + CO2 => CaCO3

CaO + H2O => Ca(OH)2

The unboiled, deionized water has a measured pH less than 7. Explain.

The water has a pH less than 7 because it reacts with carbon dioxide in the air, producing carbonic acid that drives the pH down.

Of the 6 solids placed into the respective test tubes according to table 5.1, identify the metal ion that has a characteristic

a. green color

b. blue color

c. pink color

a. NiCl2

b. CuSO4

c. CoCl2

According to the data, identify which of the following ion pairs form a precipitate

Fe3+ and Cl-

Cu2+ and (CO3)2-

NI2+ and (PO4)3+

1. no solid precipitate, they ionize

2. These do form a solid precipitate; carbonates are almost always insoluble

3. These do not form a solid precipitate as they are unbalanced.