Presentation on theme: "Ch. 2 - Measurement I. Units of Measurement (p.34-45)"— Presentation transcript:
1 Ch. 2 - Measurement I. Units of Measurement (p.34-45) Number vs. QuantitySI Base Units & PrefixesDerived UnitsDensity Calculations
2 A. Number vs. QuantityQuantity - number + unitUNITS MATTER!!
3 B. SI Units Base Unit Length- I meter m Mass- m gram g Time- t second Quantity &SymbolBase UnitUnit SymbolLength- ImetermMass- mgramgTime- tsecondsTemp- TkelvinKCurrent- IampereA
4 B. SI Units Prefix Factor mega- M 106 kilo- k 103 deci- d 10-1 centi- Pre- SymbolFactormega-M106kilo-k103deci-d10-1centi-c10-2milli-m10-3micro-10-6nano-n10-9pico-p10-12
5 D m V D= m V C. Derived Units Combination of base units. Volume - length length length1 cm3 = 1 mL dm3 = 1 LDensity - mass per unit volume (g/cm3)DmVD=mV
6 Problem Solving Steps1 Givens:2 Unknowns:3 Equations:4 Answer:
7 D m V D. Density V = 825 cm3 m = DV D = 13.6 g/cm3 An object has a volume of 825 cm3 and a density of 13.6 g/cm3. Find its mass.GIVEN:V = 825 cm3D = 13.6 g/cm3m = ?WORK:m = DVm = (13.6 g/cm3)(825cm3)m = 11,220 gDmV
8 Problem Solving Steps 1 Givens: Include quantity, number, & unit symbols2 Unknowns:Include quantity & unit symbols3 Equations:Base equation & manipulated equation4 Answer:Do the units agree? Is it reasonable?
9 D m V D. Density D = 0.87 g/mL V = m V = ? m = 25 g V = 25 g 0.87 g/mL 1) A liquid has a density of 0.87 g/mL. What volume is occupied by 25 g of the liquid?GIVEN:D = 0.87 g/mLV = ?m = 25 gWORK:V = mDDmVV = g0.87 g/mLV = 28.7 mL
10 D m V D. Density m = 620 g D = m V = 753 cm3 D = ? D = 620 g 753 cm3 2) You have a sample with a mass of 620 g & a volume of 753 cm3. Find density.GIVEN:m = 620 gV = 753 cm3D = ?WORK:D = mVDmVD = g753 cm3D = 0.82 g/cm3
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