Chemical reactions are basically divided into two major classes depending on whether the reaction lose energy or gain energy from the environment during the course of the reaction. The two classes of reaction are exothermic and endothermic reaction.
An exothermic reaction is a type of reaction in which the reaction system lose energy to the environment and thus, the energy content of the reactants is more than that of the product formed. Because of this, the enthapyl change of an exothermic reaction is always negative.
An endothermic reaction is a type of reaction in which the reaction system absorb energy from the environment. Thus, the energy contents of the products is always higher than that of the reactants and the enthapyl change of the reaction is always positive. During the course of the reaction, the reaction container is usually cold to the touch because energy is been absorbed from the environment.

4 0

2 years ago

what is the concentration (in %v/v)) of the following solutions? a. 25 mL of ethanol is diluted to a volume of 150 mL with water

fenix001 [56]

The symbol %v/v means percent by volume. Assuming there is no volume effects when these substances are mixed, we calculate as follows:

% v/v = (25 mL ethanol / 25 mL + 150 mL ) x 100
%v/v = 14.29 mL ethanol / mL solution

Hope this answers the question.

8 0

3 years ago

A double covalent bond involves two atoms sharing two electrons? True or false

jarptica [38.1K]

Answer:

False

Explanation:

A double covalent bond means 2 atoms or elements are sharing 4 electrons.

*single covalent bond shares 2 electrons.

4 0

3 years ago