Module # 5: The Chemistry of Life
One thing that we learned in this module was about changes in matter. There are two different categories of change within matter; physical change and chemical change.
Physical change – a change that affects the appearance but not the chemical makeup of a substance.
Chemical change – a change that alters the makeup of the elements or molecules of a substance.
One way to determine whether a change within matter is physical or chemical is to remember: physical changes are generally reversible; chemical changes are not.
An example of physical change would be to boil sugar water. When you put the sugar in the water, the sugar would seem to disappear. But if you boil the water off, the sugar would be left in the bottom of the pan and it would be the same as before. Likewise, if you collected the water vapor and condensed it you would have the same water as before. This is an example of physical change in that it could be reversed.
A good example of chemical change is lighting a piece of paper on fire. Once it has been burned the chemical makeup has been altered and it is impossible to get the paper back to how it was before. Because to is irreversible, it is a chemical change
Osmosis & diffusion
Diffusion – the random motion of molecules from an area of high concentration to an area of low concentration
Concentration – a measurement of how much solute exists within a certain volume of solvent
An example of diffusion is if you place some sugar in a napkin and then wrap the napkin into a small package and put a rubber band around it so that the sugar can’t escape, and then place the package with the sugar in a bowl of water. If you left it there in the water for a while and then tasted the water later you would taste sugar in the water. Why? It is because once the sugar was dissolved into the water it moved around randomly and it could go through the napkin. It was just by random chance that there was sugar in the water; it was not moved there by any mysterious force.
Osmosis – the tendency of water to travel across a semipermeable membrane into areas of higher solute concentrate.
Semipermeable membrane – a membrane that allows some molecules to pass through but does not allow other molecules to pass through.
An example of osmosis can be seen in an egg. If you soak an egg in vinegar for a while it will lose its hard shell and you will be left with a semipermeable membrane. Once the hard shell is gone you can see what the egg does in different solutions. If you place the egg in clear sugar syrup and leave it, the egg will get smaller. If you put it in plain water the egg will expand. The reason for this is that in the syrup there is a higher solute concentration outside the egg in the syrup then in the egg. The water moved through the semipermeable membrane to even out the solute concentration. The same thing happened in the water except this time there was more solute inside the egg then outside. The water moved into the egg to even out the solute concentration.
The pH scale
Two classes of molecules we learned about were acids and bases. In general, acids are substances that taste sour, while bases are substances that taste bitter.
In most of the chemical reactions that make life possible, the amount of acid or base present has a profound effect on the speed and effectiveness of the reaction. So it is important to know the level of acid or base. One way to do this is with the pH scale. The pH scale runs from 0 to 14. When a solution has a pH of 7 it is considered neutral, having no acid or base characteristics. The lower the pH, the more acidic it is. Solutions with pH from just above 7 to 14 are called alkaline and have the characteristics of a base.
We also learned about lipids, proteins and enzymes, amino acids and DNA, but sadly I have no time to tell about them. If you would like to know more, buy the book: Exploring Creation with Biology (Second edition). Have a nice day.
Animalia
One thing that we learned in this module was about changes in matter. There are two different categories of change within matter; physical change and chemical change.
Physical change – a change that affects the appearance but not the chemical makeup of a substance.
Chemical change – a change that alters the makeup of the elements or molecules of a substance.
One way to determine whether a change within matter is physical or chemical is to remember: physical changes are generally reversible; chemical changes are not.
An example of physical change would be to boil sugar water. When you put the sugar in the water, the sugar would seem to disappear. But if you boil the water off, the sugar would be left in the bottom of the pan and it would be the same as before. Likewise, if you collected the water vapor and condensed it you would have the same water as before. This is an example of physical change in that it could be reversed.
A good example of chemical change is lighting a piece of paper on fire. Once it has been burned the chemical makeup has been altered and it is impossible to get the paper back to how it was before. Because to is irreversible, it is a chemical change
Osmosis & diffusionDiffusion – the random motion of molecules from an area of high concentration to an area of low concentration
Concentration – a measurement of how much solute exists within a certain volume of solvent
An example of diffusion is if you place some sugar in a napkin and then wrap the napkin into a small package and put a rubber band around it so that the sugar can’t escape, and then place the package with the sugar in a bowl of water. If you left it there in the water for a while and then tasted the water later you would taste sugar in the water. Why? It is because once the sugar was dissolved into the water it moved around randomly and it could go through the napkin. It was just by random chance that there was sugar in the water; it was not moved there by any mysterious force.
Osmosis – the tendency of water to travel across a semipermeable membrane into areas of higher solute concentrate.
Semipermeable membrane – a membrane that allows some molecules to pass through but does not allow other molecules to pass through.
An example of osmosis can be seen in an egg. If you soak an egg in vinegar for a while it will lose its hard shell and you will be left with a semipermeable membrane. Once the hard shell is gone you can see what the egg does in different solutions. If you place the egg in clear sugar syrup and leave it, the egg will get smaller. If you put it in plain water the egg will expand. The reason for this is that in the syrup there is a higher solute concentration outside the egg in the syrup then in the egg. The water moved through the semipermeable membrane to even out the solute concentration. The same thing happened in the water except this time there was more solute inside the egg then outside. The water moved into the egg to even out the solute concentration.
The pH scale
Two classes of molecules we learned about were acids and bases. In general, acids are substances that taste sour, while bases are substances that taste bitter.
In most of the chemical reactions that make life possible, the amount of acid or base present has a profound effect on the speed and effectiveness of the reaction. So it is important to know the level of acid or base. One way to do this is with the pH scale. The pH scale runs from 0 to 14. When a solution has a pH of 7 it is considered neutral, having no acid or base characteristics. The lower the pH, the more acidic it is. Solutions with pH from just above 7 to 14 are called alkaline and have the characteristics of a base.
We also learned about lipids, proteins and enzymes, amino acids and DNA, but sadly I have no time to tell about them. If you would like to know more, buy the book: Exploring Creation with Biology (Second edition). Have a nice day.
Animalia
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