Chemistry- Mass, Change, Sig Figs and, Scientific Notation

         The main ideas that we learned this week were how to make a table and histogram for our class data and how to demonstrate it to the class. We also learned how to identify a significant figure and how to convert standard notation into scientific notation and scientific notation into standard notation. Lastly we learned how to properly measure, and which numbers were estimated. The things we learned this week are connected because they all involve learning to properly and efficiently measure things and how to demonstrate the things you have measured in graphs, tables, and whiteboards. One important detail of significant figures is how to determine if a zero in a number is significant or not. We did not do any experiments this week in chemistry but we did do class data representation and two packets on significant numbers and scientific notation. We also performed a graduated cylinder challenge.

Station 3- Reflection
The question for station three was, "Does the mass of ice change after melting?" Based on the class' data, most table groups got 0.0 grams of change in mass, but some groups got different numbers. The different numbers could have been because of forgetting to zero the scale. My table group got 0.0 grams difference. We think the mass didn't change because the atoms of ice did not increase or decrease in number just because they changed into a different form. As I learned in past science classes, when the atoms in ice melt they become more fluid and start to move around more.

Class chart for melting ice

My group's whiteboard representation

Our classes histogram

Station 4- Reflection
The question for station four was, "If you mix the blue solution and the colorless solution together will the mass of the solution change?" From the class data I would infer that the solutions when mixed had the same mass as when the weren't. Any group's data that was not 0.0 grams difference could mean they had spilled when they poured one solution into another or they may have had a faulty scale. My group got 0.0 grams. We think we got our answer because the solutions did not react with each other, they just mixed.

Our class data for mixing solutions

Our class' histogram

My group's whiteboard representation

Station 5-Reflection
The question for station five was, " If you mix sugar and water will the mass change after the sugar dissolves?" Our class' data was pretty mixed so my group wasn't sure if we were correct. My group got .3 grams difference between before the sugar was dissolved in the water and after we dissolved it. For the sugar solution to have gained mass there would have to be a chemical reaction but that doesn't seem likely. So, I believe there was a human error like not zeroing the scale or measuring incorrectly.

Our group's whiteboard representation 

Station 6-Reflection

The question for station 6 was,  "Will the mass of water change when a piece of Alka-Seltzer tablet is added?" Our class' data was all negative, but we had different variations of negative numbers. I think this was because every group got a piece of tablet but the pieces weren't exactly the same size. My group got -0.07 grams difference. We think that the mass decreased because when the tablet was added we saw bubbles and my group thought that the bubbles were taking oxygen out of the water.

Our class' histogram

Our class' data table

My group's whiteboard representation

Significant Digits and measurements-
The first thing we did in the packet was learn how to estimate numbers. We were given different rulers and we had to decide what distances we were certain about. Then we were given a rectangle lined up next to a ruler and had to measure it correctly and give the correct estimated number.

Significant Zeros-
The packet starts off by giving instructions to mass rocks and pebbles. Then you have to place the set of significant zeros in the right Rules. Then you have to place Rules on each of the numbers. Then you have to underline the significant zeros in each of the numbers. Next, we learned how to do scientific notation, which I learned in math last year, so I feel confident about it.

example of scientific notation

Graduated Cylinder Challenge-

In class we did this challenge to practice with graduated cylinders, estimated numbers, and significant figures. The first thing we did was have a member of our group go up and measure seven graduated cylinders. Once they were finished they came back to the group and we wrote our estimated numbers on a whiteboard. Then we shared our whiteboard with the class. Then we repeated these steps with a different person and different amounts of liquid.

Measurements from the second person

Measurements from the first person 

Overall Reflection-
We came to understand the ideas that we learned in class by sharing with the class and by doing power points on sig figs and scientific notation. I still have questions about significant zeros and I think we should still continue to review them in class. I think I had good participation in the activities of the past week even though I did not volunteer to do the recording in the graduated cylinder challenge. I would rate myself a nine simply because I am not confident with significant zeros. Overall I learned a lot this week even though we didn't do any experiments.

Chemistery-Mass,Change blog

        This past week we learned about changes in mass and the exploding can. These main ideas go together because the exploding can was a result of a change in mass. Most of the changes in mass were caused by chemical reactions or human error, but some just stayed the same. One example of a chemical reaction is station 1 regarding Alka-seltzer tablets. We did six different experiments to test changes in mass, but only did one experiment as a whole class on the exploding can.
                         
                            STATION #1- 

White board molecule diagram of steel
wool being pulled apart

               The first thing we did was mass the pie tin. Then we used the pie tin to mass a piece of steel wool. The next step was to pull the steel wool apart and mass it again. We found that there was no change in mass (0.0 grams). We think there was no change in mass because the molecules spread out not decreased or increased.  If the mass had decreased it would probably be due to human error such as failing to keep all of the particles of steel wool in the pie tin while pulling them apart. We used the pie tin to make sure there was no steel wool fallout while pulling the steel wool apart.

Steel wool being massed on a balance

Steel wool being massed after being pulled
apart

White Board Diagram of of steel wool
oxidizing.

                         STATION #2- 
First you mass the pulled apart steel in the pie tin. Then use the tongs to hold the steel wool and put the burner in the pie tin. Light the burner on fire then place the steel wool in the flame. Mass the steel wool in the same pie tin. Before the steel wool was burned it had a mass of 20.21 grams. After the steel wool was burned it had a mass of 21.41 grams. The change in mass was 1.2 grams. Personally I was very surprised by the results. I thought that after burning the steel wool it would loss mass or stay the same, but in fact it increased in mass. I noticed that before the steel wool was burned it was silver but after the steel wool was burned it was an indigo blue color. My table group hypothesized that the added mass after burning the steel wool happened because the steel actually oxidized and created rust on the outside.

Steel wool before being burned 

Steel wool being burned

Steel wool after being burned

                        STATION #3
First you need to find the mass of the vial and the small chip of ice.
Then let the ice melt. To help the ice melt, warm the vial with your hands. After
 the ice is melted mass it. The mass before the ice melted was 11.38 grams and the mass
 after the ice melted was also 11.38 grams. This means the when ice changes to water its
 mass doesn't change. The human error likely to happen is forgetting to zero your
 scale. This could result in incorrect conclusions.

Ice after being melted

Ice before being melted

                                                                                                                                                 
       









                    STATION #4
Find the mass of both vials with the solutions inside. Carefully mix
 the blue and the clear solutions and shake them up. Then mass the
 new mixed solution. The two solutions should become cloudy. The
 mass before mixing was 49 grams and the mass after mixing 49 grams. Mixing the
 two solutions together does not affect the mass.

Mix the clear and blue solutions
together

measure the mass of the mixed
solution and the empty vial

The mixed cloudy solution 

                       STATION #5-
Fill vial with water and put sugar in the cap. Mass the vial cap and sugar.
Mix the sugar around softly until it dissolves. When the sugar is completely
dissolved mass the solution.The mass before the vial dissolved was 44.3 grams
and the mass after the vial contents dissolved 43.9 grams The change of mass
was -.3 grams. The negative number could be the cause of human error like
 measuring wrong or not zeroing the scale.

Water and sugar before being dissolved

Water and sugar solution after being dissolved 

STATION #6-
First fill the vial halfway with water. Then put a fourth of a
Alka-seltzer tablet in the cap of the vial. Them put the vial
 and tablet on a scale and mass it out. Put the tablet in the
 water and then place the cap on the top. Look what
 happens to the tablet. The mass of the water and tablet
 before the tablet dissolves was 33.52 grams and the
 mass of the solution when it dissolved was 33.45 grams.
 The change in mass -0.07 grams.  I was surprised by this
 result because I thought after dissolving the solution would
increase in mass because of the bubbles but the solution actually
decreased in mass.

Vial of water and tablet in cap

Solution after the tablet dissolved 

I think we came to know and understand ideas this week by doing experiments and then sharing our results with the class by making charts and histograms. We also shared our hypotheses by drawing them on our whiteboards and presenting our ideas to the class.

Our class table on Station 1

Our class table for Station 2

Our class histogram for Station 2

One thing I'm still not sure about is how the burned steel wool got more mass than the wool that was not burned. I think I participated very well in the experiments this week and I also think that my table group did an equal amount of participation. From all the concepts we learned this week I rate myself a 9 because I feel pretty confident, but I still have a few questions.