Density and Exam review Day

1. Density and Exam review Day

2. Do Now (catalyst) (10 min) • 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? • What is the density of a liquid if it weighs 10g and occupies a volume of 5 mL? • What is the difference between a constant and a control? • What is the difference between the independent and dependent variables?

3. Homework 2 review • 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.

4. Homework 2 review 3. 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 Statement: Is advil or tylenol more effective in reducing fevers Hypothesis: If I take advil and tylenol, then advil will reduce my fever more because it is faster acting Independent: Advil and Tylenol Dependent: fever temperature Control: fever temperature without taking Advil/Tylenol Constants: amount of medicine, frequency of medication, etc

5. Announcements • First exam next class • Covers unit conversion, scientific method, precision/accuracy, density and lab safety • Download ‘Exam Review Notes’ from the ‘Student Notes’ section of the class website • If you have any questions stay after school or email khagan@dadeschools.net

6. Agenda / Objectives • Finish Density Lab Activity (10 min) • Precision/accuracy mini lesson (10 min) • Exam Review Stations (60 min) • Final Questions (10 min)

7. Density of water calculations • Obtain your density lab calculations from last class. Calculate the density of the water. (4 min) • Mass of water (g) =(mass of graduated cylinder + water) – (mass of empty graduated cylinder) =(final mass of g.c.) – (initial mass of g.c.) • Volume of water (mL) – level of water shown on graduated cylinder • Density (g/mL) = mass/volume • Once you are finished, complete the rest of your density calculations in the tables

8. Were our measurements accurate or precise? Precision = how close measurements are to each other Accuracy =how close the measurements are to the “true” value

9. Density Lab Observation Questions (10 min) Answer the following questions in your lab notebook: • 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)? • 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? • The density of aluminum is 2.70 g/cm3. What volume will 13.5 grams of aluminum occupy? HINT, use unit conversion!

10. Exam review stations (60 min) • There are 4 stations at the lab benches, you will have 15 min at each station. • If you have questions, first look at notes, then ask group member, finally ask teacher • This is your LAST CHANCE to practice before the exam, USE YOUR TIME WISELY! • Review problems are similar to exam problems • All answers are posted online

11. Any Final questions?

12. Problem What is the density of 35 g of a metal if the metal raises the level of water in a graduated cylinder from 25 mL to 30 mL? 30 mL 25 mL

13. Problem A mystery liquid has a density of 10 g/mL. What is the mass of 5 mL of mystery liquid?

14. Problem • Silver has a density of 10.5 g/cm3. What is the volume of a 5.25g silver coin in cubic centimeters?

15. Problem If you wanted to see which makes you gain more weight, eating hot cheetos for lunch or eating snickers for lunch. Your experiment would have: • Independent Variable: __________________________________ • Dependent Variable: ____________________________________

16. Problem • If you wanted to see which makes you gain more weight, eating hot cheetos for lunch or eating snickers for lunch. Your experiment would have: • Independent Variable: __________________________________ • Dependent Variable: ____________________________________

17. Problem • If you wanted to test if drinking milk helps you jump higher, your experiment would have: • Independent Variable: __________________________________ • Dependent Variable: _________________________________

18. Problem Ms. Van Duyn decides to do a little experiment on her students. She tells one group of students not to study for the test. She then has another group stay after school to study for one hour. She has a third group stay after school and study for two hours. When the students take the test, she compares the grades the different groups got.

19. Problem A baker decides to do a chemistry experiment. He makes four different cakes. He adds no flour to the first cake. He adds two cups to the second cake, three cups to the third cake, and four coups to the fourth cake. He then checks how high the cakes rise

20. Problem A student wants to find out if diet coke helps her stay up late. She doesn’t drink diet coke one night. The next night she drinks one diet coke. The next night she drinks two diet cokes. She notes the time she starts to feel sleepy each night.

21. Problem In the North, the government puts salt on the roads during the winter to melt the ice. Some environmentalists are worried that this is harmful to plants near the roads. To test this theory they perform an experiment. They have a control group of plants and an experimental group. No salt is given to the control group of plants for two weeks. Salt is put in the soil of the experimental group for two weeks. At the end of the two weeks the growth of the two groups is measured.