Yes. Cyclohexane has covalent bonds and is an organic compound. Yes. Cyclohexane has covalent bonds and is an organic compound.
The short answer is that they are not always weaker in fact. Some ionic compounds have very strong bonds, while some covalent bonds are quite weak. Usually however, it is easier to break an ionic bond than a covalent one. What determines the actual strength of a bond is quite complex, but let me try to explain the basic principles. Bonding has everything to do with electrons. In ionic bonds, an element loses an electron to another element. The two elements are then bonded by a force of attraction based on electrostatics, or Coulombic force; it is due to the fact that a positive charge and a negative charge attract each other (like the two opposite ends of a magnet). Since one element has a negative charge and the other has a positive charge they are held together in a bond. I will give an example. Sodium chloride, NaCl, or more commonly known as table salt, is an ionically bonded compound. The sodium, Na, will lose one electron (to form a Na+ ion), and the chlorine, Cl, will gain that electron (to form a Cl- ion). Since an electron has a negative charge, the sodium has a positive charge (lost a negative), and the chlorine has a negative charge (gained a negative). Just like north and south magnets, the two are attracted to each other and are bonded. The bond strength is determined by how much charge each element has. For instance, you can also have ions that have more than one charge. Common ions like this are Mg2+, Fe3+, and O2-. Because each ion has more than one charge, the attraction is even stronger because the Coulombic force is directly related to the size of the charge on each ion. In covalent bonds, elements share electrons. No electrons are given away or taken completely, but are instead shared between the elements. For example, Nitrogen gas, or N2 is simply two nitrogen atoms bonded together. There is no reason for one N to give an electron to the other one. They both want to hold on to their electrons exactly the same amount! (As opposed to NaCl in the example above, where Cl needs an extra electron, and Na needs to get rid of one to become most stable). The strength of a covalent bond is determined by a complicated set of properties of the atoms involved. What makes a covalent bond weak or strong is really beyond the scope of this discussion. (Briefly, the strength of covalent bonds is related to the nature of the atomic orbitals involved in the bond, specifically the overlay of the orbitals involved in the bond, and the size of the energy difference between the orbitals. If that doesn't make sense, don't worry too much about it... it's complicated stuff!) In general, ionic bonds are easier to break, but it depends on several factors. For instance, breaking ionic bonds is very easy to do when you dissolve an ionic compound in water. Water is special because it effectively reduces this Coulombic attraction between the plus and minus charges on the ions (it kind of acts like a barrier or shield, blocking the plus from seeing the minus). However, if you were trying to break an ionic bond in a perfect vacuum, it would be much harder (because without something to block the attractive force, it is quite strong). Another thing to consider is that ionic compounds usually form 3-dimensional crystals, where there are many many ionic bonds, whereas covalent bonds tend to be found in isolated molecules (except for network covalent compounds like diamond or silicon). The fact that ionic bonds form a 3-D structure in a crystal makes a huge difference. So part of what makes this question so complicated is that you kind of comparing apples and oranges.
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Perchloric acid is a strong acid, whereas potassium hydrogen phthalate (KHP) is a weak acid. Therefore, perchloric acid will protonate KHP to form phthalic acid. In other words, even though both are considered acids, KHP is more basic than perchloric acid (when you compare their pKa or Ka, the true measure of acid strength).
I'm not entirely sure what you mean by "standardized" however. Do you mean doing a titration? Often a solution of KHP is used to calibrate a pH meter because it's pH in solution is very stable. I would be surprised if a titration was done with perchloric acid and KHP however, but I'm not sure what else you could mean by asking why an acid is standardized using KHP.
KHP is the primary standard used for the standarization of perchloric acid, usually 0.1M HCLO4 in concentration. It is the recommended primary standard in the pharmaceutical industry for analytical testing using perchloric acid for non-aqueous titration determinations. The protonation of KHP to phthalic acid when reacted with perchloric acid can be determined stoichiometrically. Using a dried KHP standard of known purity allows the determination of HCLO4.
Ionic compounds conduct electric current when they are molten because the constituent ions that form the compound appear when the solid form changes phase into the liquid one. The solid structure of the compound, which is generally a crystalline one, comes apart when it melts, and in a way similar to what it does when that compound dissolved in a solvent. This frees the ions, and their mobility means that they can contribute to the movement of electric current. It's just that simple.