Binary Acids - Online Tutor, Practice Problems & Exam Prep

Binary acids are covalent compounds consisting of hydrogen ions (H⁺) bonded to nonmetal anions, excluding those with oxygen. They include acids like hydrobromic acid (HBr) and hydrosulfuric acid (H₂S). The strength of binary acids is determined by their ability to dissociate in water. Strong binary acids, such as hydroiodic (HI), hydrobromic (HBr), and hydrochloric (HCl) acids, dissociate completely, making them strong electrolytes that donate protons readily. However, hydrofluoric acid (HF) is a weak binary acid, partially dissociating and favoring its molecular form, thus behaving as a weak electrolyte.

The strength of binary acids can be compared using electronegativity and atomic radius. For elements in the same period, the greater the electronegativity, the stronger the acid. Conversely, for elements in the same group, a larger atomic radius correlates with stronger acidity. These trends help predict the relative strengths of binary acids based on their position on the periodic table and the properties of the non-hydrogen element they are bonded to.

Binary Acid Formation

Hey everyone, So here we're going to say that binary acids represent covalent compounds containing the H ion bonded to a nonmetal anion, not including oxygen. OK, so binary acids are acids that do not possess oxygen within themselves.

So if we took a look at two typical types of binary acids, let's look at H+ connecting to Br-. Remember, when the numbers are the same in terms of their charges, they just simply cancel out. So our acid here would be HBr, which is hydrobromic acid.

And then here let's do H+ connecting to SH-. Again, the numbers are the same, they just simply cancel out. So this becomes H₂S. This is representing hydrogen, sulfur, hydrosulfuric acid, right?

So here we have two typical types of binary acids. So remember, when we're looking at a binary acid, it does not possess oxygen.

Binary Acids Example

Which of the following represents the possible structure of a binary acid? Remember, a binary acid is an acid that does not contain oxygen. If we take a look at the first one, we have a covalent compound beginning with the hydrogen. So yes, it is an acid, but the presence of oxygen means it is not a binary acid.

The next one isn't an acid at all. It's barium chloride. There's no H ions anywhere. The next one we have is HF. It's covalent. It starts with a hydrogen, so it's an acid. It has no oxygen, so it is a binary acid. This is hydrofluoric acid.

Then finally we have LIH. Now here, this is an ionic compound and more importantly, it is a metal cation connected to a basic anion. It is Li positive, H minus. This is an example of a base. Now if you didn't see that, make sure you go back and take a look at my videos where I talk about bases and the introduction of them. So here this would be a base.

Out of all the choices, the only one that is a binary acid is option C.

Binary Acid Strength

Now that we know how to identify binary acids, let's talk about their strengths. We're going to say that our Halo acids are Halo acids. Well, they're the only strong binary acids that exist and involve an H plus ion attached to a halogen. Remember, your halogens are your group 7A elements and the most important halogens on the periodic table are fluorine, chlorine, bromine and iodine.

Now of these, the strong binary acids are hydro, iotic acid, hydrochromic acid and hydrochloric acid. So those would be HI, HBR and HCL, which would be these three here. Notice that I have not included flooring. That's because hydrofluoric acid represents a weak binary acid. We'll talk about that later on on why it's considered a weak binary acid and the other three are considered strong.

Now recall also that strong acids represent strong electrolytes and weak acids represent weak electrolytes. We're going to see here that strong acids dissociate or ionize completely in water, and we're going to say that they donate a proton easily. When we say proton here, we're talking about the H ion. We're going to say that weak acids only partially dissociate our ionize. It donates a proton less readily, so not as easily, and it favors reactants, meaning it doesn't really want to break up into ions too much or rather stay in its molecular form.

Here we have an example of hydrochloric acid and hydrocyanic acid. Both of these are binary acids. Hydrocyanic acid is one of our strong Halo acids. It breaks up 100% into H plus ions and CL minus. To illustrate this, we use a solid arrow going forward and we're going to say since it's a strong acid, it associates completely, which we see in the form of these two ions. It easily donates an H plus. In reality, it's donating this H plus to the water that surrounds it. We'll see later on on how that works. And then we are making 100% of both of these ions. So basically all of this is gone. The strong HCL is completely ionized. It's gone. It's all been transformed into the ions. So it favors a product side.

For our weak acid, we have hydrocyanic acid, HCN. So if it's a weak acid, we're going to have the use of two arrows, we're going to have a larger arrow moving backwards, and we're going to have a smaller arrow moving forward. OK, so you can show it like this or you could show it like this. Both are correct. And what this is showing me is that the larger error what's going which is going in the reverse means that the reverse direction, the reactant side is more greatly favored. The smaller arrow moving forward means that very little of these two ions are produced.

So we're going to have less H plus and CN minus ions being produced. So HCN associates, partially meaning that there's going to be more molecules of HCN than there are ions of H plus. And CN minus less readily donates protons, so HCN doesn't easily give away an H plus to the water. And again the larger arrows pointing towards the reactant so the reactant side is more greatly favored. So keep this in mind when we're talking about the strengths of binary acids.

Binary Acids Example

The following represent aqueous acid solutions. So identify the strong acid, the weak acid and the weakest acid. So here we have HA as the general formula for Oregon generic formula for an acid. Here when it breaks up, it gives us H⁺ ion and A^- ion. Here we're told that HA is in this form. H⁺ would be this smaller H⁺ ion. A^- represent this larger gold sphere.

Now if you are strong acid, you completely ionize. You make 100% of these two ions, so you should have none of this remaining. If we look at our options, which one shows that? Well, if we look, it's the middle one. The middle one, we have only these two. There is none of this hanging around. So this represents our strong acid. The other two are weak because we have a lot more of the accident tax than we do ions being produced.

But we have to identify which one is weak and which one is weakest. So if we take a look here, let's try to look at how many we have of each. We have 1, 2, 3, 4, 5, 6, 7 seven of these HAs for the first one. And then how many H⁺ do we have? We have two H⁺ 1/2 and then two A^-, 1, 2. What about over here? Over here we have 1, 2, 3, 4, 5, 6, 7, 8, 9 nine HAs and only one H⁺ and 1A^-. O. We can see there's a lot more of the acid intact, so very little of it has broken up. So this would have to be our weakest acid 'cause it dissociates or ionizes the least, and then this one will be a weak acid.

So that's how we look at and depict each of these aqueous acid solutions. Remember, it all hinges on the fact that an acid, if it's strong, completely ionizes or dissociates into ions. A weak one only partially dissociates. The less it dissociates, the weaker the acid will be.

Comparing Binary Acid Strength

Well, we know there are three strong binary acids, HI, HBR, and HCL, and we still need to know how to compare binary acid strengths. Nonetheless, because you could be asked to compare the strengths of two strong binary acids or to compare the strengths between weak binary acids, how exactly would we do that?

Well, we're going to say here that the strength of binary acids is based on the electronegativity or atomic radius of the non-hydrogen element. So if we take a look at a typical periodic table, we're looking at electronegativity. As we go from left to right on the periodic table, electronegativity, abbreviated EN, would increase. And if we go down any group, we're going to say that atomic radius, abbreviated AR, would also increase.

OK, so these are the directions that allow these two periodic trends to increase. Now how does this relate to the strength of binary acids? We're going to say here when comparing the strengths of binary acids if the elements are in the same row, then use electronegativity to compare their acid strengths. So here we're going to say the greater the electronegativity of the non-hydrogen element, then the more acidic the acid.

If elements are in the same group or column, then use atomic radius in order to compare their acid strengths. Here we're going to say that the greater your atomic radius, then the more acidic your acid, right? So these are the concepts, periodic trends we're going to use to compare the strengths of different binary acids to one another.

Binary Acids Example

Which is the weakest acid from the following. So here we have HF, HCL, HI, HBR or all are equal if we look at the periodic table. Remember we're looking at the non hydrogen element found within the binary acid. So we need to compare fluorine, chlorine, bromine and iodine to one another when they're in the same group.

Remember we look at atomic radius and we say the higher the atomic radius then the more acidic the acid. If we look, iodine would have the largest atomic radius out of the four elements. As a result of this, HI would be the strongest acid, but here we're looking for the weakest.

The one with the smallest atomic radius would be fluorine, so HF would be our weakest acid. So here option A is the correct answer.

Binary Acids Example

Now there will come times when we're comparing binary acids and they're not found within the same. Or row, or not found within the same group or column O. What exactly do we do? Well, we're going to say that if the binary assets are separated by one period, then use electronegativity to compare their acid strengths. If separated by more than one period then use atomic radius to compare their acid strengths.

If we take a look here at this example question, it says which is the weakest acid. From the following we have H₂S, HF, H₂Te, H₂S or they're all equal. We have to look at the non hydrogen element of the binary acid. So we are comparing selenium, fluorine, tellurium and sulfur. We want the weakest acid here. All right. So if we take a look, we're going to say that sulfur, selenium, and tellurium are all within the same group. Since they're all within the same group, we look at atomic radius.

The larger the atomic radius, the stronger the binary acid. So H₂Te would be stronger than H₂S. H₂Se would be stronger than H₂S. So these two are out. Since they're both stronger than H₂S, we know that they couldn't be the weakest acid. So that means we now have to compare HF versus H₂S. So how do we determine which one is weaker? Well, we're going to say here, if binary assets are separated by one period, then we look when we use electronegativity to compare their acid strengths.

Fluorine is in the second period, sulfur is in the third period. They're only separated by one period from one another. If we look at electronegativity, fluorine is more electronegative than sulfur. Fluorine is the most electronegative element on the periodic table, so that would mean that HF is more acidic than H₂S. So by process of elimination, option D would be the best answer. It is the weakest acid out of all the options given.

Which of the following acids would be classified as the strongest? 

a) CH₄             b) H₂Te            c) H₂S             d) PH₃             e) BH₃

• A. CH₄
• B. H₂Te
• C. H₂S
• D. PH₃
• E. BH₃

Here’s what students ask on this topic:

Which substance is a binary acid?

A binary acid is a compound that contains only two different elements: hydrogen and one other nonmetal. The general formula for a binary acid is HX, where H stands for hydrogen and X represents the nonmetal. An example of a binary acid is hydrochloric acid (HCl), where hydrogen is combined with chlorine. Other examples include hydrobromic acid (HBr), hydroiodic acid (HI), and hydrofluoric acid (HF). These acids are called "binary" because they consist of two elements. When dissolved in water, binary acids release hydrogen ions (H⁺), which are responsible for the acidic properties of the solution.

What is a binary acid?

A binary acid is a chemical compound that contains only two different elements: hydrogen and one other nonmetal element. The general formula for a binary acid is HX, where H stands for hydrogen and X represents the nonmetal element. When dissolved in water, binary acids release hydrogen ions (H⁺), which is what makes them acidic. The strength of a binary acid depends on the ease with which it can donate a hydrogen ion. This is influenced by the bond strength between the hydrogen and the nonmetal atom; weaker bonds usually mean stronger acids. Common examples of binary acids include hydrochloric acid (HCl), hydrobromic acid (HBr), and hydroiodic acid (HI). These acids are widely used in various industries and in laboratory settings for different applications, such as pH adjustment, cleaning, and as reagents in chemical reactions.

Which of these is not a binary acid?

A binary acid is a compound that contains hydrogen and one other nonmetal element, typically forming an acid when dissolved in water. Binary acids have the general formula HX, where X is the nonmetal element. To determine which of these is not a binary acid, you would look for a compound that does not fit this description.

For example, hydrochloric acid (HCl), hydrobromic acid (HBr), and hydroiodic acid (HI) are all binary acids because they consist of hydrogen and a halogen. However, if you encounter a compound like sulfuric acid (H₂SO₄), it is not a binary acid because it contains hydrogen, sulfur, and oxygen. Sulfuric acid is instead classified as an oxyacid because it includes oxygen in addition to hydrogen and another nonmetal (sulfur in this case).

So, if you're given a list of compounds, the one that includes oxygen or more than two elements is not a binary acid.