Explain the concept of aldol condensation and which are the molecules that obey it.
Aldol condensation is a condensation reaction in which 2 molecules of aldehydes or ketones with alpha- hydogen undergo a condensation reactions in presence of dilute alkali, resulting in the formation of a beta-hydroxy aldehyde (aldol) or a beta-hydroxy ketone(ketol). In this reaction the second molecule gets attacked by a hydroxy ion to form deprotonated aldehyde, which further attacks the first unreacted molecule to form a condensed product with negative charge on oxygen atom. This gets further attacked by water to form aldol/ketol. Some part of them readily lose water to form unsaturated product .
What is the shape of water molecule and how is it obtained??
The shape of water molecule is bend or V-shaped. This can be easily understood by considering the VSEPR theory. Water belongs to AB2E2 category , i.e. 2 bonds and and 2 lone pairs. Here oxygen has 6 electrons , out of which two are involved in bond with Hydrogen and 2 lone pairs. These are arranged in such a manner that the lone pair- lone pair repulsion is reduced ,i.e the lone pairs are kept as far as possible. In order to reduce the the bond pair-lone pair repulsion the 2 bond pairs come closer making it decrease from 109.4 degree (the tetrahedral angle) to 104 degree , hence obtaining the V-shape
How is blood grouping done? And why is it important to match blood group before transfusion?
Basically we follow the ABO blood grouping system , by Karl Landsteiner. In this system ,the blood is grouped to A, B ,O also as positive and negative. The grouping is done based on the presence of antigens (proteins) A and B on the erythrocytes or the red blood cells. If it has A antigen and B antibody then its A group.If it has B antigen and A antibody its B group. If it has both A and B antigens and no antibodies , then its O blood group. The positive and negative grouping is done based on the presence( then positive ) or absence(then negative ) of Rh (Rhesus ) factor. If the blood groups are not matched then blood coagulation will happen