When two aqueous solutions are mixed together and the temperature of the solution decreases, the reaction is called an endothermic reaction with a positive enthalpy change. Endothermic reaction is when heat is absorbed by the reaction taking place. All endothermic reaction always have a positive enthalpy change.
Answer;
- A teacher takes the cap off a permanent marker. A few minutes later, students at the back of the classroom complain about the odor of the marker.
- A cooking school student burns a piece of toast. Soon, the entire kitchen smells like burnt toast.
- Toxic fumes produced by a chemical factory are detected in the air in a town several miles away.
<h3><u>Explanation;</u></h3>
- Diffusion is a type of passive transport that involves the movement of particles from a region of high concentration to a region of low concentration.
- <em><u>Diffusion takes place in liquids and gases, since their particles can move randomly from one region to another.</u></em>
- <em><u>Therefore, diffusion results from the random movement of particles in which the net movement is down the concentration gradient that is, from a region of high concentration to a region of low concentration.</u></em>
Calcium has only two valence electrons in its shell. In order to agree with the octet rule it bonds with oxygen which has 6 valence electrons and with hydrogen which has 1 valence electron. Hope this answers the question. Have a nice day.
