About half of the hydrochloric acid produced annually in the...

About half of the hydrochloric acid produced annually in the United States (3.0 billion pounds) is used in metal pickling. This process involves the removal of metal oxide layers from metal surfaces to prepare them for coating. (a) Write the overall and net ionic equations for the reaction between iron(III) oxide, which represents the rust layer over iron, and HCl. Identify the Bronsted acid and base. (b) Hydrochloric acid is also used to remove scale (which is mostly $\mathrm{CaCO}_{3}$ ) from water pipes (see p. 126). Hydrochloric acid reacts with calcium carbonate in two stages; the first stage forms the bicarbonate ion, which then reacts further to form carbon dioxide. Write equations for these two stages and for the overall reaction. (c) Hydrochloric acid is used to recover oil from the ground. It dissolves rocks (often $\mathrm{CaCO}_{3}$ ) so that the oil can flow more easily. In one process, a 15 percent (by mass) HCl solution is injected into an oil well to dissolve the rocks. If the density of the acid solution is $1.073 \mathrm{g} / \mathrm{mL},$ what is the $\mathrm{pH}$ of the solution?

About half of the hydrochloric acid produced annually in the United States (3.0 billion pounds) is used in metal pickling. This process involves the removal of metal oxide layers from metal surfaces to prepare them for coating. (a) Write the overall and net ionic equations for the reaction between iron(III) oxide, which represents the rust layer over iron, and HCl. Identify the Bronsted acid and base. (b) Hydrochloric acid is also used to remove scale (which is mostly $\mathrm{CaCO}_{3}$ ) from water pipes (see p. 126). Hydrochloric acid reacts with calcium carbonate in two stages; the first stage forms the bicarbonate ion, which then reacts further to form carbon dioxide. Write equations for these two stages and for the overall reaction. (c) Hydrochloric acid is used to recover oil from the ground. It dissolves rocks (often $\mathrm{CaCO}_{3}$ ) so that the oil can flow more easily. In one process, a
15 percent (by mass) HCl solution is injected into an oil well to dissolve the rocks. If the density of the acid solution is $1.073 \mathrm{g} / \mathrm{mL},$ what is the $\mathrm{pH}$ of the solution?

Key Concepts

pH Calculation and Concentration Conversions

pH is a measure of the acidity of a solution expressed as the negative logarithm of the hydrogen ion concentration. Determining the pH of a solution, especially when given in terms of mass percentage and density, involves converting those values into molarity. This is a crucial skill in analytical chemistry because it links concentration measurements with the pH scale, allowing chemists to predict and control the reactivity of acid solutions.

Stoichiometry in Multi-Step Reactions

Stoichiometry involves balancing chemical equations to ensure mass and charge conservation, which is essential in multi-step reactions such as the conversion of calcium carbonate through intermediary bicarbonate formation to carbon dioxide. It ensures that each stage of the reaction is correctly accounted for and that overall reaction yields and reactant quantities can be determined accurately.

Net Ionic Equations

Net ionic equations focus on the chemical species that participate directly in the reaction, omitting the spectator ions that do not undergo any change. This simplification highlights the actual process of proton transfer or electron transfer in acid?base or redox reactions and is a key tool for understanding reaction mechanisms in aqueous solutions.

Bronsted–Lowry Acid–Base Theory

The Bronsted–Lowry theory defines acids as proton donors and bases as proton acceptors. This concept is fundamental for understanding reactions where acids react with compounds like metal oxides or carbonates, as it explains how the acid donates a proton to a base, initiating a series of chemical transformations that can be described by both overall and net ionic equations.

Transcript

00:01 Okay, we are going to look at three real -world examples.

00:05 Example number one, we're going to talk about metal pickling, and a huge amount of hydrochloric acid is used in the united states for metal pickling.

00:17 And this process is the removal of metal oxide layers from metal surfaces to get them ready for coatings.

00:25 And we're going to talk about the removal of rust, which is iron three oxide, f .e .203.

00:33 This is rust.

00:36 And hydrochloric acid is used to remove rust.

00:42 My products will be iron three chloride and water.

00:52 Now this is an unbalanced chemical equation.

00:55 This is aqueous.

00:56 I'm putting it way down there.

00:57 I apologize.

00:58 And it looks like i will need a six and a two and a three.

01:04 Okay.

01:06 Now we are asked to write the balanced chemical equation, which we did.

01:09 And we are also asked to write the net ionic equation.

01:14 I'm going to cheat a little bit, and i'm going to just write in orange my aqueous substances that are going to dissociate.

01:24 So i have 6 -8 pluses and 6 chlorides on this side of the equation, and here i have 2 iron 3 cations and 6 chlorides.

01:41 So my spectator ions will be the chlorides.

01:48 Then i'm going to write the full net ionic equation, which is what i just had up above, except i'm going to take out my spectators, 6h plus, and i have 2, fe3 plus, and 3h2s.

02:12 And that needs an aq.

02:14 There.

02:15 So our first problem is done.

02:18 Oh, i think i also have to identify the bronstad acid and base.

02:25 So we are going to identify the bronstead acid and base.

02:28 And that's not too hard here because, you know, it's got hydrochloric acid in it.

02:32 So hydrochloric acid is the bronstead acid, and this is our bronstead base.

02:49 Okay, now that part is done.

02:52 Our second problem, we are going to be looking at the use of hydrochloric acid to remove scale.

03:00 And scale is calcium carbonate, mostly, and hcl.

03:11 Calcium carbonate.

03:12 Now, this is a two -step process.

03:14 So we are told that it produces the, where am i here? it produces the bicarbonate ion.

03:22 So this is going to produce the bicarbonate ion.

03:28 And my other substance it's going to produce will be calcium chloride.

03:43 And the next part, my h -c -o -3, my bicarbonate ion, also reacting with the h -cl.

03:55 In this case, we'll produce, of course, co2, which is a gas, and i'm going to get a c -l -minus, which is aqueous, and h -2...

Please give Ace some feedback