Reactions in Aqueous Solution

Precipitation Reaction

Precipitation occurs when ions in solution “swap partners” to form a new compound of low solubility in water. This low-solubility compound forms as solid particles that eventually settle which is called the "precipitate".

To predict whether a precipitate will form, you need to  know which substances are soluble in water and which  are insoluble.

Example.

These reactions are Double Displacement reactions, otherwise known at Metathesis Reactions, because the cations effectively change places. Here, the Pb2+ cation displaces the K+ cation and combines with the Iodide (I-) to form PbI2. Likewise, the K+ cation displaces the Pb2+ cation to combine with the Nitrate (NO3-) to form KNO3. 

Acid-base Reaction

An acid-base reaction is one in which an acid reacts with a base to form a salt and water.

Redox Reaction (Oxidation-Reduction Reaction) is a type of chemical reaction that involves a transfer of electrons between two species. Oxidation is the loss of electrons. Reduction is the gain of electons. Each reaction is called "half-reaction" simply because we need the two to have a whole reaction.

Precipitation and acid-base reactions are sometimes known as ion exchange reactions. Ion exchange reactions also include gas forming reactions. Ion exchange reactions are a type of reaction where the positive ions exchange their respective negative ions due to a driving force.

A number of tests can be used to identify whether certain anions (chlorides, bromides,

iodides, carbonates, sulphates) are present in a solution.

Redox Reaction is a class of reactions that include:

– formation of a compound from its elements

– all combustion reactions

– reactions that generate electricity

– reactions that produce cellular energy

Oxidizing agent is the species doing the oxidizing.

Reducing agent is the species doing the reducing.

Instantaneous Acceleration Sample Problem

1. The fastest measured pitched baseball left the pitcher’s hand at a speed of 45.0 m/s. If the pitcher was in contact with the ball over a distance of 1.50 m and produced constant acceleration, (a) what acceleration did he give the ball, and (b) how much time did it take him to pitch it?

Instantaneous Velocity Sample Problem

1. A car is stopped at a traffic light. It then travels along a straight road so that its distance from the light is given by  (a) x(t)=bt^2-ct^3, where b=2.40m/s^2 and c=0.120m/s^3.   Calculate the average velocity of the car for the time interval to (b) Calculate the instantaneous velocity of the car at and (c) How long after starting from rest is the car again at rest?
Answer: