Maths All Formulas Needed for IGCSE

Which acid is stronger between HCl and H2SO4?

Which acid is stronger between HCl or H2SO4?

This is not a completely straightforward question. HCl and H2SO4 are categorized asstrong acids. That means that they are about 100% ionized in water. In water all of the strong acids are of essentially the same strength. This happens because water is a leveling solvent. In water the strongest acid that can exist is H3O+, or hydronium ion. Thus, in order to be able to tell which of the strong acids above is stronger you have to use a different solvent for the acids like, for instance, CH3COOH, or 100% pure acetic acid. In solvents such as this we can see which of the strong mineral acids is actually the strongest. In this case, the references below reveal that HCl is a bit stronger than H2SO4, although in water they are essentially the same strength.

The ionization of each of the acids is written below.

HCl(g) + H2O(l) --> H3O+(aq) + Cl-(aq)

H2SO4(l) + H2O(l) --> H3O+(aq) + HSO4-(aq)

Physics:All Definitions needed for IGCSE Exam

Chemistry: Condensation Polymerisation (Things you need to know)

Condensation Polymerisation

I have personally had some trouble completely understanding condensation Polymerisation.......Here is what you should know for your IGCSE Chemistry Examination on Condensation Polymerisation :

You should know that monomers that are joined by condensation polymerization have two functional groups. You should also know  that a carboxylic acid and an amine can form an amide linkage, and a carboxylic acid and an alcohol can form an ester linkage. Since each monomer has two reactive sites, they can form long-chain polymers by making many amide or ester links. Let's look at two examples of common polymers made from the monomers we have studied.

Example 1:
A carboxylic acid monomer and an amine monomer can join in an amide linkage.

As before, a water molecule is removed, and an amide linkage is formed. Notice that an acid group remains on one end of the chain, which can react with another amine monomer. Similarly, an amine group remains on the other end of the chain, which can react with another acid monomer.

Thus, monomers can continue to join by amide linkages to form a long chain. Because of the type of bond that links the monomers, this polymer is called a polyamide. The polymer made from these two six-carbon monomers is known as nylon-6,6. (Nylon products include hosiery, parachutes, and ropes.)

Example 2:
A carboxylic acid monomer and an alcohol monomer can join in an ester linkage.

A water molecule is removed as the ester linkage is formed. Notice the acid and the alcohol groups that are still available for bonding.