Answer:
Exothermic reaction for the HCl, endothermic reaction for the water

Explanation:
Heat was lost by HCl as its temperature lowered, so it was an exothermic reaction for the HCL.
Heat was gained by water as its temperature increased, so it was an endothermic reaction for the water.
m = Mass of water = 100 g
c = Specific heat of water = 
= Change in temperature of water = 
Heat is given by

Heat gained by water is
.
Answer:
Increasing the surface area of the reactants
Explanation:
An increase in surface area of the reactant will always cause an increase in the rate of reaction. This is so because, an increase in the surface area of the reactant will cause the reactant particles to collide effectively thereby bringing about an increase in the reaction rate.
Collision theory suggests that for a reaction to occur, the reactant particles must collide with the right orientation. As the surface area of the reactants are increased, the reactants particles collide more with the right orientation bringing about definite increase in the rate of reaction.
Answer:
P³⁻ + Cl⁻ --> PCl₃
Explanation:
PCl₃: phosphorus trichloride. prefix in front of chloride is "tri"–meaning three.
So I’m not 100% sure what you’re asking but I’m going to give it a go. The elimination reaction is a term used in organic chemistry that describes a type of reactions. The name kinda tells you what’s going to happen. Something is going to be removed/eliminated from initial reactant/substrate and as a result, an alkene (double bond containing compound) will form.
In elimination reactions a hydrogen atom is first removed (as a H+) from the beta carbon. As a result, the left behind electrons create a pi bond between the beta carbon and the neighboring alpha carbon. This promotes the electronegative atom, on the alpha carbon, to leaves the substrate taking both electrons from the shared sigma bond with the alpha carbon.