What Is Chemistry? The study of all substances and the changes they undergo.

Scientific Method, Measurements & Math Chapter 1&3 Scientific Method, Measurements & Math

Scientific Method

Scientific Method p. 6 Warm up: Describe an experiment you conducted in your past. What did you learn? Question- this is something you want to know more about. It can be tested. Hypothesis- after research, you will come up with a possible explanation. “If, then…” Experiment- you plan and carry out an activity that tests your hypothesis. Included are a list of materials and detailed procedures to follow. Variables are conditions you change in order to see if your hypothesis is true.

Controls are conditions that are not changed that you compare your variables to. Independent variables are variable you control in your experiment. Dependent variables are affected by your independent variables. Only one variable can be changed at a time! Data tables- used to record the measurements taken during an experiment Graphs- are used to help you see relationships between variables. 3 types… Conclusion- a statement that determines if your hypothesis was correct or not.

Identifying variables p5 Circle the dependent variable and underline the independent variable in the following: A student determines which soil is best for growing plants. A student measures how much the temperature changes as a solution is heated. A student conducts a survey to determine which type of music is most popular.

Observations & Inferences p5 Write down 4 observations you can make based on the reciepts. Write down what you think you know know about this person based on their receipt. (inference)

S.I. Units & Prefixes p8 Warm Up: what do you think the difference is between a theory and a law?? SI units are a revised version of the metric system used all over the world. Length- meter; volume- (m3) Mass- kg Time- second Quantity- mole Temp- kelvin Electric current- ampere, Luminosity- candela

Measurements p8 ‘Accuracy’ is how close a measurement is to the actual value. (does the scale give you your true weight?) ‘Precision’ is how close the measurements are to each other.(does the scale give you the same weight all the time?)

Accuracy vs Precision p7 On the top of your left page, draw 2 dart boards. Label one “accuracy” and the other “precision”. Draw darts showing where they would land. Accuracy (not precise) Precision (not accurate) Where would the arrows be if the shooter was accurate and precise?

“King Henry Died By Drinking Chocolate Milk” Metrics p8 http://scaleofuniverse.com/ “King Henry Died By Drinking Chocolate Milk” 1000 100 10 1 10 100 1000 Kilo, hecto, Deca, BASE, deci, centi, milli Larger units (liter) Divide! (meter) (gram) (second) Smaller units. Multiply!

Metrics practice p7 Convert 5 ml to liters: Convert 100 cm to meters: Convert 10 grams to mg: Convert 25 deciliters to kl: Convert 60 cm to km:

Significant figures p10 Warm up: with a ruler, measure the length of a crayola marker to the nearest millimeter. Include all certain digits plus one uncertain or estimated digit WHY? The last digit in a recorded measurement is always an estimation. 3.20? 3.21?

p.10 All nonzero digits are significant Ex) 37755 The Rules for Sig Figs... Sandwiched zeroes are sig Ex) 4005 has 4 Leading or trailing zeroes may be sig Atlantic-Pacific Rule 5600 has 2 2004600 has 5 0.003000 has 4 30.40800 has 7

24.37 m How many figs are sig in these? 240.37 cm 240 mL 0678.2 km

Scientific Notation review p10 Convert to standard notation: 3 x10 8 (Positive exponent moves right, negative moves left) = 300 000 000 Put 245.86 into scientific notation: (move decimal to after the first digit, left is positive, right is negative)= 2.4586 x10 2 *Keep all sig figs!

Sig fig and scientific notation practice p9: copy the practice problems from the projector and complete in you notebook

Calculating with sig figs p12 Warm up: round to nearest whole number: 452.7, 999.9, 34.3 When multiplying and dividing, the answer can have no more sig figs than the least number of sig figs in any factor. When adding & subtracting, the answer is rounded to the least number of decimal places of any of the factors. When calculations have both, round after each step according to rules 1&2

Calculation Practice p11 Copy the problems from the projector into your notebooks and complete.

Calculation quiz Perform the following calculations. Round your answer correctly. 5+51.4= 50 x 0.005=

Factor Label Method(Dimensional Analysis) p14 Warm up: write down driving directions from SECTA to jack in the box. Factor label is a method of solving complex math and science problems. Ex: How many inches in 2.36 yards? Ex: How many seconds are in 2.65 years?

Equal to the mass of an object Density p14 Equal to the mass of an object divided by its volume. D = Mass (g) Volume (ml)or(cm3) Ex. What is the mass when 13 ml of a liquid has a density of 2.3 g/ml? Ex. What is the volume of a 5.6 g cube that has a density of 1.45 g/cm3?

Convert 35,000 seconds to days. Use factor label method. Factor label quiz Convert 35,000 seconds to days. Use factor label method.

Density Quiz What is the density of a cube if it weighs 3.4 g and each side is 2.75cm? (round to sig figs)