How to Use a Balance and How sweet is it?
Problems: 1. Learn how to use a balance by: Measuring Mass Directly, find the Mass by Difference, and measuring out a Chemical Substance
2. How much sugar is chewed out of a piece of Bubblicious Bubblegum over time?
3. About how much sugar is there in a piece of Bubblicious Bubblegum?
4. Investigate science standard: 9. Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will:
a. Plan and conduct a scientific investigation to test a hypothesis.
d. Recognize the slope of the linear graph as the constant in the relationship
and apply this principle in interpreting graphs constructed from data.
e. Construct appropriate graphs from data and develop quantitative statements about the relationships between variables.
g. Distinguish between linear and nonlinear relationships on a graph of data.
Hypothesis: ______% of sugar in gum
Materials: balance, piece of gum, 100 ml beaker, graduated cylinder, paper towel, salt, small objects
Procedure: Before you measure the mass of any object, be sure all riders are moved to the left and that the pointer rests at zero. If necessary, slowly turn the adjustment knob until the pointer rests at zero. This is called zeroing out the balance. Make sure your balance is clean and still.
Part A. Measure Mass Directly
1) Find a small object. Place on balance pan. The beams will rise and the pointer will point above zero.
2) Move a rider on one of the middle beams until the pointer stays below zero. Move the rider back one notch.
3) Move the rider on each beam until you are able to get the pointer to rest at the zero. The mass of the object is equal to the sum of the readings on all 4 beams.
4) Record the mass to the nearest tenth of a gram in the data table.
5) Remove this object and repeat these steps 2 more times with two different solid objects. Record your results.
Part B: Finding the mass by Difference
1) Find the mass of a clean, empty 100ml beaker. Record the mass in the Data table.
2) Using a graduated cylinder, carefully measure out 50ml of water.
3) Pour the water into the beaker and find the mass of the beaker and water. Record the mass. Find the mass of the water.
Part C: Measuring Out a Chemical Substance
1) Place a piece of paper on the balance pan and find its mass. Record the mass.
2) Add 5 g to the mass of the weighing paper and move the riders to this number.
3) Obtain a sample of salt. Add small amounts of salt to the paper on the balance until the pointer rests on the zero. Record the total mass of the weighing paper and the salt.
4) Dispose of the salt in a proper location.
Part D:
1) Mass a piece of bubblegum, still in the wrapper. Record data on column A.
2) Carefully unwrap gum, saving the wrapper, and when told to “GO!” start chewing until told to stop (3 min.) Record the mass of the wrapper during this time in column B.
3) Place gum in your wrapper and remass the A.B.C gum. Record data in column D.
4) When told to “GO!” start chewing your same piece of gum again until told to stop (6 min. total time )
5) Place gum in your wrapper and remass the A.B.C gum. Record data.
6) When told to “GO!” start chewing your same piece of gum again until told to stop (9 min. total time).
7) Subtract all masses from the wrapper’s mass. Record in column E.
8) Determine the amount of sugar in the gum by subtracting the chewed mass from the unchewed mass and record in column F (C-E).
9) Determine the ratio of sugar to total gum mass by dividing the difference by the unchewed gum mass. (F/C)
10) Determine the % of sugar by multiplying the ratio by 100. (G x 100)
11) Record this amount on the Class Results chart.
12) Make a stem and leaf graph of the amount of sugar in the gum (% from class H-9 min).
13) Make a pie graph using the class mean, to show the % of sugar (from H-9min) and the % of other material in the gum.
14) Make a line graph showing how sugar decreased in the gum over time (C & E).
Data:
Table Part A
Object / Mass (g)Table Part B
Mass of the Empty Beaker (g) / Mass of beaker with 50 ml of water (g) / Mass of the water (g)Table Part C
Mass of the salt (g) / Mass of the weighing paper (g) / Mass of weighing paper and salt (g)Table Part D
Name / AMass of gum with wrapper
(g) / B
Mass of wrapper
(g) / C
Mass of gum – wrapper (g)
A-B / D
Mass of chewed gum with wrapper
(g) / E
Mass of chewed gum – the wrapper
(g)
D-B / F
Amount of sugar
(g)
C-E / G
Ratio of sugar to gum
F/C / H
Amount of sugar in gum (%)
G X 100
A
B
Time (min) / 0 / 0 / 0 / 3 / 6 / 9 / 3 / 6 / 9 / 3 / 6 / 9 / 3 / 6 / 9 / 3 / 6 / 9
Class Results Table: Amount of Sugar in Gum (%) (H-9 min.)
Team / Partner A / Partner B / Team / Partner A / Partner B1 / 10
2 / 11
3 / 12
4 / 13
5 / 14
6 / 15
7 / 16
8 / 17
9 / 18
Class Average (mean): ______
Class Median: ______
Class Mode: ______
Class Range: ______
When making your graphs: make sure the graphs are neat (use a ruler or compass), each graph is on a page by itself, titled, X and Y axis are labeled, and use color if appropriate.
Do a RERUNS conclusion and make sure you answer all problems in the second R. You should have learned how to use a balance, find the amount of sugar in a piece of gum, and learned to display your data in the appropriate graphs.