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## Catalyst

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**Catalyst**• If I have a can of coke and I put it in a bowl of water, will it sink or float? What about a can of diet coke? • Convert 3 mL to ounces • A scientist wants to test his hypothesis: If I use fertilizer on my lawn every day then my grass will grow taller because it’s receiving more nutrients • Write a scientific question and identify the independent variable, dependent variable, control and constants**Objectives**• SWBAT calculate the density of objects by using measured mass and volume • SWBAT compare densities of various objects**Agenda**• Teacher demos • Density Lecture • Density Essential Lab Activity • Calculate Densities Measured • Precision vs Accuracy • Lab Results and Conclusions**Apply it to real life:**What makes Coke different from diet Coke? More sugar Less sugar**So what can we conclude about density?**More dense = sink Less dense = float**Definition of Density**• Density: the amount of matter per unit of space of an object But what does that really mean?**Compare Thing 1 and Thing 2**Which of these has more matter? Which has more space? So which one is the most dense? Thing 1 Thing 2**Compare Thing 1 and Thing 2**Matter/ Matter/ Space Space Less dense Thing 1 Thing 2 More dense**Definition of Density**• Density: the amount of matter per unit of space of an object But what does that really mean? • How compact or packed together the matter is in the space of an object. • This is a property of matter that does not change with the amount of the object**Compare Thing 3 and Thing 4**Which of these has more matter? Which has more space? So which one is the most dense? More dense Thing 4 Thing 3 Less dense**Liquid Layers – Check it out!**• Which liquid has the highest density? • Which liquid has the lowest density? • Which liquid has the middle density? Can you tell the density of something by looking at it?**Definition of Density**• Density: the amount of matterper unit of space of an object Matter:per:Space: Mass Volume**Formula for Density**D = m = mass = g or g V volume mL cm3 Tools: scale and ruler/graduated cylinder**Density Lab and Sample Calculations**• Rotate around the room and visit each of the 5 Stations At each station, you will find instructions on what to do along with some questions. • After taking all necessary measurements and answering the questions at the station, rotate to the next station. • Note: Do not calculate the density, we will do that as a class • Once you have visited every station, return to your seat.**Density Lab and Sample Calculations**• What is your data obtained for water? • What is your volume? • What is the mass? • What is the density of water?**Density Lab and Sample Calculations**What is your density for the water?**Precision vs Accuracy**Precision = how close measurements are to each other Accuracy =how close the measurements are to the “true” value**Density Lab and Sample Calculations**Now calculate the densities for each of the stations in your lab composition book**Density Lab Observation Questions**Answer the following questions in your lab notebook: • What is the density determined for your water sample? • What could you do to improve the accuracy of your measurements? • How does the density of the weight compare to the density of water? Which is denser? • Nickel (metal) has a density of 8.91 g/mL. Compare this to the density of the nickel coin you calculated. Is the nickel coin made of pure nickel (metal)?**Density Lab Conclusion Questions**Answer the following questions in your lab notebook: • When you use the terms heavier or lighter to compare different objects with the same volume, what property of the objects are you actually comparing? • Would you expect the densities of various fruit juices in the same container to all be the same? Explain. • How can the concept of density be used to differentiate between a genuine diamond and an imitation diamond? • The density of aluminum is 2.70 g/cm3. What volume will 13.5 grams of aluminum occupy? HINT, use unit conversion!**Homework # 2: Due Next Class**Homework can also be downloaded from the class website • What is the density of 10 g of a metal if the metal raises the level of water in a graduated cylinder from 25 mL to 45 mL? • What is the density if 50 g of a metal occupies a volume of 5 cm3? • If you were trying to test whether Advil or Tylenol reduced fevers more, write a problem statement, hypothesis and variables for an experiment you could perform.**Problem 1**Osmium is a very dense metal. What is its density if 50.00 g of the metal occupies a volume of 2.22 cm3? lecturePLUS Timberlake**Solution**D = mass = 50.00 g = volume 2.22 cm3 = 22.522522 g/cm3 = 22.5 g/cm3 lecturePLUS Timberlake**Problem**What is the density of 48 g of a metal if the metal raises the level of water in a graduated cylinder from 25 mL to 33 mL? 33 mL 25 mL lecturePLUS Timberlake**Solution**Volume (mL) of water displaced = 33 mL - 25 mL = 8 mL D = mass = 48 g = volume 8 mL = 6 g/mL lecturePLUS Timberlake