Questions: What is Matter? What is Density? How can we make a golf-ball float? How dense does water need to be to make a golf-ball float?
Hypothesis:
Materials: Jars (2 per table), Long plastic spoons (2 per table), Measuring spoons (2 per table), Measuring cup (2 per table), Triple beam balance, Golf-ball (2 per table), Water, Food coloring, Cling wrap (2 per table), Paper and pencil, Jars with salt (2 per table), Permanent marker, (2) Calculators, (2) Rulers
Procedures for Day 1:
1. Place the lid of jar (open end up) on tray of Triple Balance – find the mass of the lid. Record your information. (This is now your new starting point, so you will need to subtract this number when finding the mass of the golf ball.)
2. Place the golf ball in the in the open lid. (Subtract mass of the lid from this new measurement to find the mass of the golf ball in grams.) Record your answer.
3. Remove lid and reset your balance to “0”.
4. Find the mass of your empty glass jar without its lid. Record your measurement in GRAMS (g).
5. Remove jar and reset balance to “0”.
6. Find the mass of your empty measuring cup. Record measurement in GRAMS (g). DO NOT RESET BALANCE.
7. Fill your measuring cup to 250mL. Use balance to find the mass of the water filled measuring cup. Record your measurement in GRAMS (g).
8. Fill the measuring cup with exactly another 250mL and pour into jar. Keep track of how many times you pour 250mL of water into the jar until it is ¾ of the way full.
9. Find the volume of water in your jar using the metric system: Calculate how many mL of water you have in the jar. Take the mass measurement for 250mL of water and multiply this by the number of times you filled the jar with the measuring cup. (This will give you the volume of water inside your jar. The metric system works well in this situation. For example, 1mL of water is equal to 1 cubic centimeter of volume.) Record your volume measurement in cubic centimeters.
10. Find the estimated volume of the jar using a formula: Compare your last measurement by making an estimate using the formula:
Volume = Length x Width x Height:
a.) Use ruler to measure the length of jar (this is the measurement of the bottom edge facing you). Record your answer as the Length.
b.) Use the ruler to measure the width of jar (this is the measurement of the bottom edge adjacent to the length edge. Record your answer as the Width.
c.) Use ruler to measure the height of the jar (measure from bottom of jar to the level of the water – remember water should be filled to only 3/4 of the jar). Record your answer as the Height
d.) Multiply all three sides to find the approximate volume of jar, using this formula: V = L x W x H
e.) Compare both results: What did you find out? How are they similar, how are they different? Record your results.
11. Write your name and period on the tape strip of your jar using a permanent marker. Put the cap on the jar and give to your teacher.
12. **Create your own hypothesis by using the questions above (“If I do this, then I think this will happen because…”):
Procedures for Day 2:
1. Find out how many grams = 1 tablespoon (Tbl.) of salt:
a.) Put plastic wrap on tray of balance.
b.) Slide all weights to the far left. Make sure the arrow is set at the “0” mark.
c.) Put one (1) tablespoon of salt on plastic covered tray.
d.) Record mass measurement of 1 tablespoon of salt on your paper.
2. Put the golf-ball in the jar filled with water. Record what happens. Why?
3. Use measuring spoon (tablespoons – Tbl.) and add salt. Put full Tbl. spoons, one spoonful at a time, in jar and STIR, using the long plastic spoon.
4. Record what happens.
5. Repeat steps 3 and 4 UNTIL golf-ball floats to the top of jar.
6. Add a SMALL AMOUNT of FRESH WATER to the jar (the golf-ball should sink to the middle of the jar).
7. Your teacher will put four drops of food coloring in the jar. DO NOT SHAKE OR STIR! Observe what happens. Why?
8. Calculate how many total grams of salt you used to make the golf-ball float.
9. Use the formula: Density = Mass ÷ Volume. Find the density of the salt water needed to make the golf-ball float. Record your findings.
10. How do you know the density of the water was changed in the jar?
11. Describe how the molecules in fresh water act in the jar. What happened to the fresh water molecules when salt was added to the jar?
12. Think about why food coloring was added to the jar after some fresh water was added to your jar; speculate how the molecules are acting differently in the two different types of water in the jar.