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Chapter 1B Notes

Chapter 1B Notes. -Physical and chemical changes are usually accompanied by energy changes energy - the capacity to do work work - action of a force (push or pull) through a distance kinetic energy (KE)- energy of motion potential energy (PE)- energy of position

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Chapter 1B Notes

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  1. Chapter 1B Notes -Physical and chemical changes are usually accompanied by energy changes energy- the capacity to do work work- action of a force (push or pull) through a distance kinetic energy (KE)- energy of motion potential energy (PE)- energy of position -potential energy is converted to kinetic energy when a force acts on an object total energy = KE + PE

  2. thermal energy- energy associated with the temp of an object ex- weight held up high (PE), then dropped (KE), then hits the ground (thermal energy) -KE is transferred into the ground increasing the temp of the ground a slight amount Law of Conservation of Energy- energy is neither created nor destroyed -back to example- PE becomes KE which becomes thermal energy and is released -when potential energy is high, object is less stable

  3. Measurement International System of Units (SI) – system of measurement based on the metric system used by scientists globally Length- size, distance -basic unit is the meter (m) 1 meter = 39.37 inches -Find your height in meters!!!

  4. Mass- the amount of matter in an object -basic unit is the kilogram (kg) 1 kg = 2.2 lbs -Find your weight in kilograms!! weight- measure of the pull of gravity on a given mass -mass is always the same, but weight can change -weight on the moon is 1/6 your weight on the Earth -Find your weight on the moon!!

  5. Volume- the amount of space an object occupies -basic unit is the Liter (L) 1 L = 1.06 quarts -anything cubed is also a volume **1 milliliter = 1 cm3 HOW?? (length)(width)(height/thickness) = volume (cm)(cm)(cm) = cm3 (cc) = mL Time -basic unit is the second (s) -most familiar unit of measurement

  6. Temperature- how hot or cold something is, average kinetic energy -basic unit is kelvin (K) -avoids negative numbers by assigning coldest temperature possible (-273°C or 459°F) at 0K, absolute zero 273 K = 0°C K°C = K - 273 °C K = °C + 273 -Celsius (°C) is mostly used by scientists

  7. °F  °C = (°F -32) ºC ºF = (1.8)(ºC) + 32 1.8 -Convert normal body temp of 98.6°F to °C and Kelvin!! (98.6°F = 37°C = 310K) Common Conversions 1km = 0.62 mi 1m = 39.37 in 1in = 2.54 cm 1kg = 2.2 lbs 1lb = 453.59 g 1oz = 28.35g 1L= 1.06 qt 1 gal = 3.79 L

  8. Metric System -based on scales/multiples of 10 -uses prefixes to convert numbers **Table** Practice 980 fg = ? ng 1000 mm = ? µm 20 EL = ? GL 300000000 ag = ? pg 10000 dm = ? km 1.2 hL = ? nL 1300000 cg = ? Dg 3 00 Mm = ? Tm 4000000000 L = ? PL 4300 nm = ? mm

  9. Density- ratio of the mass of a substance to its volume *page 20 Table 1.4 Density = mass/volume d = m/V density = g/cm3 or g/mL mass = (density)(volume) m = dV volume = mass/density V = m/d Page 20- Example 1.3

  10. intensive property- property that is independent of the amount of substance ex- density extensive property- property that depends on the amount of a substance ex- mass Scientific Notation -used to make large numbers look smaller and small numbers look larger

  11. Significant Figures -in science, measurements are reported so that every digit is certain except for the last one Rules for Counting Sig Figs • all non zero digits are significant • all zeroes between two #’s are significant • all zeroes to the right of a # without a decimal point are NOT significant • all zeroes to the right of a # with a decimal point are significant

  12. 5) all zeroes to the left of a number containing a decimal point are NOT significant • if counting, all numbers are significant Examples 1100m 0.00130ML 2003g (2) (3) (4) 3000 cars 456 17.80 (4) (3) (4)

  13. Atlantic Rule -if a decimal point is absent, start counting from the first non-zero digit from the Atlantic Ocean side inland (right  left) Pacific Rule -if a decimal point is present, start counting from the first non-zero digit from the Pacific Ocean side inland (left  right) **All #’s significant when counting 10400L 308g 0.00240m 0.40500L 230L 0.04020g 5600mg 200 pens

  14. Multiplying/Dividing Sig Figs -the answer must have the same number of sig figs as the factor with the fewest sig figs Ex- (40)(56)(340) 761600 800000 (1 sig fig) Ex- 2.0035 ÷ 3.20 0.626094 0.626 (3 sig figs)

  15. Adding/Subtracting Sig Figs -the result must have the same number of decimal places as the quantity with the fewest decimal places Ex- 2.345 + 0.07 + 2.9975 5.4125 5.41 (2 decimal places) Ex- 5.9 – 0.221 5.679 5.7 (1 decimal place)

  16. Problems With Multiple Operations Ex 1.002 – 0.999 3.754 0.003 3.754 0.0007991 0.0008 (1 sig fig) Try pg. 26 Ex 1.6 and pg. 27 Practice 1.6

  17. Precision- how close a series of measurements are to one another Accuracy- how close measured values are to the actual value *Can be precise, but not accurate or vice versa

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