Cranidia( Anna Mkrtchyan)
Author
Anna Mkrtchyan
Science is based on observations and inferences. An observation is a record resulting from the study of an event or object, whereas an inference is a conclusion drawn from evidence or reasoning based on observations.
Principle(s) Illustrated
The principle that at a constant temperature the concentration of a gas dissolved in a fluid with which it does not combine chemically is almost directly proportional to the partial pressure ofthe gas at the surface of the fluid.
Henry's law is one of the gas laws and was formulated by the British chemist, William Henry, in 1803. It states that:
At a constant temperature, the amount of a given gas dissolved in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.
Cgas= kPgas
where Cgas is molar concentration of the gas in the solution,k is Henry;s law constant for that gas at a particular temperature, and Pgas is partial pressure of the gas above the solution. (k is approximately 3.5 × 102 M atm for CO2 at 25C)
Standards
Gases and Their Properties
4.The kinetic molecular theory describes the motion of atoms and molecules and explains the properties of gases. As a basis for understanding this concept:
a.Students know the random motion of molecules and their collisions with a surface
create the observable pressure on that surface.
b. Students know the random motion of molecules explains the diffusion of gases.
c.Students know how to apply the gas laws to relations between the pressure, temperature, and volume of any amount of an ideal gas or any mixture of ideal gases.
Questioning Script
Prior knowledge & experience:
As the result of many different scientists and experiments, several gas laws have been discovered. These laws relate the various state variables of a gas. Calculations in atmospheric chemistry depend strongly on the availability of kinetic and thermodynamic data. For gas-phase chemistry, evaluations such as the IUPAC or JPL data sets greatly facilitate obtaining reliable values.
Root question:
How do these creatures swim to the surface and dive back? or How do they congregate on the bottom before swimming to the top?
Target response:
Carbonated soft drinks are packaged under pressure, forcing a large amount of carbon dioxide to dissolve in solution. Bubbles of carbon dioxide form on the surface of the submerged cranberries, and the cranberries are soon buoyed to the surface where the bubbles break, causing the cranberries to sink.
Henry's law does not work if there is a chemical reaction between the solute and solvent.
Common Misconceptions:
The higher the temperature of the gas, then more gas will dissolve.
Solution:gas cannot be a solute.