Arrange these acids from weakest to strongest: HClO2, HCN, HF, HCl
Ik the order is :
HCN < HF < HClO2 < HCl
but how exactly does one come to that conclusion with no necessary given information (Ka values?). Is there a way to memorize? or a trick? to know what acid is stronger than the other by the chemical formula.
Thanks!
http://clas.sa.ucsb.edu/staff/Resource%20folder/Chem109ABC/Acid,%20Base%20Strength/Table%20of%20Acids%20w%20Kas%20and%20pKas.pdf
You have them right, so you do have to look at Ka.
so without Ka one wouldn't be able to find out the order?
Not exactly, all you can do without Ka is approximate, depending on the structure of the cation. It is only very rough.
To determine the relative strength of acids, you can use certain principles and trends in acid strength. One important factor to consider is the polarity of a bond.
1. HCN: Hydrocyanic acid is a weak acid. It contains a polar bond between hydrogen and nitrogen (H-N) but lacks a highly electronegative atom, such as oxygen, to stabilize the negative charge.
2. HF: Hydrofluoric acid is slightly stronger than HCN. It contains a polar bond between hydrogen and fluorine (H-F) and has a small amount of stabilization from the electronegative fluorine atom.
3. HClO2: Chlorous acid is stronger than HCN and HF. It contains a polar bond between hydrogen and oxygen (H-O) and also has resonance structures that spread out the negative charge, providing additional stability.
4. HCl: Hydrochloric acid is the strongest acid in this series. It contains a polar bond between hydrogen and chlorine (H-Cl). The electronegativity difference is larger than in the previous examples, and chlorine is a highly electronegative atom, allowing for greater stabilization of the negative charge.
While memorization is possible, it is more effective to understand the underlying principles of acid strength. Factors such as bond polarity, electronegativity, and resonance structures can help you determine the relative strength of acids.