Accelerated Chemistry Blog #2

Diffusion of food coloring in water.

In chapter 2 thus far, we have discussed many interesting topics and concepts.  The first of these included the motion of particles in matter and  how the speed and movement of these is affected by temperature.  To discover more about these ideas, we performed several activities in class.  The first of these was when Mr. Grosshuesch sprayed an apple-scented substance into the air.  We, the students, were instructed to raise our hands when the scent reached where we were sitting.  We noticed that over time, the students farthest from where the substance was sprayed began to raise their hands.  This showed us that over time, the spray which was in the form of gas, completely filled the room due to collisions.  This is called diffusion.

The second activity pertaining to particle motion was when we dropped food coloring into two different containers of water.  One contained hot water, and one contained cold water.  We observed that the food coloring moved more quickly in the container that had the hot water.  This helped us discover that the rate of diffusion, or how quickly a substance fills a container, increases when the temperature increases.

The third activity pertaining to the motion of particles was when we watched internet simulations of particle movement and answered questions about theses simulations.  This showed us the effect collisions between particles have on each other.  One particle in the collision will slow down and the other will speed up.  Although the total energy has stayed the same, it has been transferred from one particle to another.

The final activities we did that pertained to the motion of particles were the rising of the colored liquid up the pipette as the beaker with water was heated below and the blowing of the garbage bags.  This showed that as the colored liquid heated up, there was more particle movement.  This caused it to rise up the pipette.  In the garbage bag demonstration, we blew on straws into the garbage bag, inflating it.  This happened because the air particles continually collided with the sides of the bag and bounced back.

The second big concept we discussed were solids, liquids, and gases and how they are similar and different.  We learned about this through Mr. Grosshuesch doing simple demonstrations and by watching "Eureka" videos.  Through all of this we discovered solids have a definite shape and volume whereas liquids have a definite volume but they take the shape of their container.  Gases have an indefinite volume and also take the shape of their container.  In addition, gasesn are compressible, liquids are slightly compressible, and solids are not compressible.

The third concept we covered was that of temperature and thermal energy.  Thermal energy is the speed of particles whereas temperature is what is used to measure this speed.  Although there are many temperature scales, many scientists use the Kelvin scale.  You can convert Celsius, another common temperature scale, to Kelvin by adding 273.  At 0 K, there is no particle motion and it is called "absolute zero."

The fourth concept we explored was air, atmospheric, and gas pressure.  Air/atmospheric pressure is pressure exerted by air particles in all directions.  Gas pressure is caused by the collisions of gas particles with the walls of a container.  Gas pressure is measured using mm Hg, atm, or kPa (760 mm Hg = 1 atm = 101.3 kPa).  The final notes we took on this topic were about manometers.  A manometer is an instrument used to measure gas pressure.

To illustrate this fourth concept, we performed a few experiments and demonstrations.  The first of these was heating a soda can with water inside.  After heating we placed the can upside down in a beaker of cold water.  The can exploded and crushed.  This occurred because while heating, the air pressure could escape out of the top of the can.  However, when we turned it upside down, the air pressure was too strong and crushed the can.  The second demonstration we did was creating a barometer.  We did this by filling a 3 foot tube with mercury and placing it upside down in an evaporating dish filled with more mercury.  Instead of the mercury all draining into the dish, it was held up in the tube by air pressure.  We measured how high the mercury stood in the tube and found out what the air pressure in the room was.

Accelerated Chemistry Reflection Blog #1

It's been an exciting beginning to the school year in Accelerated Chemistry!  During the first two weeks, I, along with the class, learned about the basics of chemistry and science in general by performing multiple labs and discussing these topics during class.  Some of these basics include: matter, mass, physical and chemical changes, and measuring volume.  Using these principles, along with other previous knowledge, we, as a class, will explore more in-depth topics in the weeks to come.

On the first day of school, my group and I constructed a boat that consisted of simple materials, such as cardboard, plastic, duct tape, and straws.  Since each material had a separate cost, our goal was to be able to float the most pennies on our boat for the least amount of money.  My group used cardboard, straws, and regular tape to construct our boat.  It ended coming in second place in our class.  This experiment wasn't necessarily meant to teach us about a certain topic, rather to introduce us to how we would be working in groups often and presenting our findings and thoughts.

The next activity we did during class was a lab on mass and change.  In this lab, we picked our groups and performed several tasks in which a substance or object underwent some sort of change.  Both before and after performing each task, my group had to weigh the substance or object.  After this we determined the change in mass and drew pictures of the activity, both before and after, to show changes.  Through this lab, I learned about systems, surroundings, and mass.  A system is the part of the universe that we a focusing on.  In the case of the lab, the system was activity that we were doing.  Surroundings are anything in the universe other than the system.  In this case the surroundings were everything thing around us during the experiment.  Finally, I learned that the mass of an object is represented by the number of particles in that object.

After this lab, we took the knowledge we had learned and started discussing some other topics.  Because we already had learned about what mass was, we could now use this to discover what the Law of Conservation of Mass/Matter was.  This states that matter can neither be created or destroyed and the number of particles stays the same.  It also states that the mass of an object or substance will stay the same if nothing enters or leaves the system.  The next topic we discussed were physical and chemical changes.  A physical change is a change to an object that does not modify, or alter, its chemical makeup.  A chemical change is a change that provides new substances with changed chemical properties.  To help our understanding of these topics, we did another lab in which we did five different activities.  Each activity represented a physical or chemical change in which we needed to identify.

To cap off our first two weeks of classes, we learned about volume and how to measure it.  My group was given a regular shaped solid on which we marked five different heights on the side.  By measuring the height, width, and length of the solid, we calculated the volume of the container up to the various marks on the side.  After this, we filled water up to each mark and then dumped the water into a graduated cylinder.  This graduated cylinder measured how many milliliters of water was inside of the solid.  By finding both how many milliliters of water were in the solid, and what the volume of the solid was, we deduced that one centimeter cubed is equivalent to one milliliter.

I felt that the first two weeks of class went very well for me.  I learned the basics of chemistry which are going to be essential in learning and knowing more during the coming year.  I would rate my understanding of all of the topics we have discussed this year so far as very well.  I believe that part of the reason I understand everything so well is because we do many labs.  These labs give me a chance to see for myself how the topics we discuss actually work.  In addition, it is easier to stay engaged while doing an experiment in comparison to a teacher explaining notes.

Brad Bermke
P.S. I sent a video to your email since it wasn't uploading on here.  Thanks.