Question

Four point of difference between dilute sulfuric acid and concentrated sulpuric acid

Answer 1

A concentrated acid is an acid which is in either pure form or has a high concentration. Laboratory type sulfuric acid (about 98% by weight) is a concentrated (and strong) acid.

A dilute acid is that in which the concentration of the water mixed in the acid is higher than the concentration of the acid itself. For instance, 5% sulfuric acid is a dilute acid

1. With metals 
Most metals react with dilute sulfuric acid to give hydrogen. 
Zn + H2SO4 = ZnSO4 + H2 
the same metals will react differently with concentrated sulfuric to give Sulfur dioxide gas
Zn + 2H2SO4 -----heat------> ZnSO4 + SO2 + 2H2O 

2. Metals below hydrogen in the activity series 
There is NO REACTION with dilute sulfuric acid 
With conc sulfuric, it is similar to Zn 
Cu + 2H2SO4 -----heat------> CuSO4 + SO2 + 2H2O 

3. Adding to equal volume of water 
Dil sulfuric ... No reaction, virtually no temperature change. 
Conc sulphuric ... Dangerous, violent reaction, solution boils 
H2SO4 + H2O = H3O+. + SO4 2- 

4. Conductivity 
Dil sulfuric ... Good electrical conductor due to ions present 
Conc sulphuric .. No elecrtrical conductivity as no ions present. 

5. Addition to a hydrated salt 
Dil sulfuric ... It just dissolves 
Conc sulfuric .. Removes water of crystallisation as strong affinity for water eg copper sulfate crystals turn white.