1st Semester Exam Review

Lab Equipment Test tubes Watch glass Beakers Erlenmeyer flask Graduated cylinder Triple beam balance

Lab Equipment Which of the following measure volume?

Lab Equipment First read the liquid at eye level Measuring Volume First read the liquid at eye level Second, read the volume at the curve of the meniscus.

MEASUREMENTS What is this measuring device called? What is it used to measure? What is the curved line called? What is the measurement? Which is more precise: a graduated cylinder or a beaker? Why? Graduated Cylinder Volume of liquids Meniscus 50 .0 mL Graduated cylinder is more precise because it measures in smaller intervals.

Lab Equipment Which of the following measure mass?

MEASUREMENTS 1. What is this measuring device called? _______________ 2. What is it used to measure? _________________ 3. What is the measurement below? ___________ 4. What are the correct units? ________________ Triple Beam Balance Mass of solids 365.4 grams Grams (g)

Precision vs Accuracy What is precision? What is accuracy? Precision indicates how close together or how repeatable the results are. A precise measuring instrument will give very nearly the same result each time it is used. What is accuracy? Accuracy indicates how close a measurement is to the accepted value. For example, we'd expect a balance to read 100.00 grams if we placed a standard100.00 g weight on the balance. If it does not, then the balance is inaccurate.

Which of the following is more precise? Why? MEASUREMENTS Which of the following is more precise? Why? The first one is more precise because it measures in smaller intervals.

A student measured the length of a piece of string that was 64 A student measured the length of a piece of string that was 64.34 cm long. Her measurements were 64.32 cm, 64.34 cm, 64.35 cm, and 64.34 cm. Which of the following statements is true? The measurements were accurate but not precise. The measurements were precise but not accurate. The measurements were both precise and accurate. The measurements were neither accurate nor precise.

Lab Safety General guidelines Safety first! Your main responsibility in lab is to prevent injuries of yourself and your partners!! Never work alone. Always read the directions before starting the lab. Know where all safety equipment is located and emergency contact numbers. No eating and drinking in lab (or tasting the chemicals!) Report ALL accidents to teacher.

Lab Safety continued…. Eye protection and Clothing Before starting lab, tie back long hair, roll up sleeves. Put on any protective equipment that teacher requires: Ex: apron, lab coat, goggles, gloves, closed-toe shoes, etc.) Always wear approved GOGGLES while in lab…**even if you are NOT conducting an experiment at the time. No contact lenses in lab The eyewash is available to rinse out hazardous chemicals in the eye.

Disposal Safety AVOID HAZARDS Use caution when handling hot glassware. When diluting acid, always add acid slowly to water. Never add water to acid. Always read the directions or consult your MSDS when disposing chemicals!!

During a lab activity, isopropyl alcohol is splashed into a student’s eyes. What should the student do? A Run to the nurse’s office B Put on safety goggles C Flush eyes with water D Wipe eyes with a cloth

Scientific Method How many

Data Trends How many students do you predict will have a cell phone by the year 2009? 15 thousand 18 thousand 19 thousand 20 thousand

What is a hypothesis? Hypothesis A hypothesis is an educated guess that can be tested by experimentation.

Theory What is a theory? An explanation of things or events based on many observations. Can it be changed? YES!! It can be changed as new data uncovers new information.

Which statement is true about a theory? A. A theory can not be changed according to new data. B. A theory does not have to be repeated, because it based on only one observation. C. A theory is an explanation of things and events based on many observations. D. A theory is can never become a law.

Units: meters per sec (m/s) Speed is how fast you are going. Units: meters per sec (m/s)

Position vs time graph The position vs time graph shows where things are at different times Speed is the slope of the position vs time graph

5 secs 275 m 150m / 5 sec =30 m/sec speed

time position 14 m 14 m / 4 sec = 3.5 m/s speed

speed B A

Acceleration & Momentum

What is acceleration? rate at which speed changes Rate of change means the ratio of the amount of change divided by how much time it took to change What is acceleration?

vf – vi t Formula Unit Units of cm/sec2 or m/sec2 2nd velocity 1st velocity vf – vi t time Units of cm/sec2 or m/sec2

Positive acceleration (speeding up) Deceleration (slowing down) Zero acceleration (constant speed)

Acceleration is the slope of the speed vs. time graph DON’T WRITE