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U1D7: Density and Thickness of Aluminum Lab Do Now: (Calculators needed!) 1. Measurement Lab due 2. Density Lab out for check 3. Check HW #3 answer sheet and green pen (6.5 min) Today: 1. Rounding Check 2. Density Lab 3) Rounding Homework 1) ADDITION ( Choose any 3) 22.313 32.0059 32.0 MW 0.66242 0.66 g 0.0945 345.788 174.767 0.095 km 22.3 cm 346 mmol 174.8 cg Problem Unrounded Answer Rounded Answer, with units 16.55 16.6 mg 32.405 32.405 cL 32.3151 32.32 J 362.98 363 kg 1.00115 1.0012 km 959.99677 960 cg 22.95 mg – 6.4 mg = 33.728 cL – 1.323 cL = 32.32 J – 0.0049 J = 378.98 kg – 16 kg = 1.00345 km – 0.0023 km = 960 cg – 0.00323 cg = Problem Unrounded Answer Rounded Answer, with units 199.6666667 _ 3 200 g/cm 5.0063113 5.006 g/cm3 0.01 0.01 cal/g 0.8190082 0.819 g/km 7.1097694 7.11 g/mol 14.4 10 g/L 4792 g / 24 cm3 = 7139 g / 1426 cm3 = 3.00 cal / 300 g = 19.82 g / 24.2 km = 64.77 g / 9.11 mol = 144.0 g / 10 L F) OK, here is a practical problem in which you will combine all of your skills. 1) A ring, supposedly made of pure silver (Ag) has a mass of 20.445 grams. When its volume is taken by water displacement, it is found to have a volume of 1.95 mL. Calculate the density of the ring: D = m/V D = (20.445 g) / (1.95 mL) D = 10.4846125 g/mL D= 10.5 g/mL 2) Based on the actual density of silver (Ag) found on Reference Table S, could this ring actually be made out of silver? Briefly explain your answer: Yes – Ag has a listed density of 10.500 on Reference Table S. Density and Thickness of Aluminum Lab Objective: I will successfully use known properties of Aluminum to determine the thickness of a sheet of aluminum foil to the correct level of precision. Pre-Lab: Why are you determining the density of aluminum in this lab? How does the density of aluminum foil differ from the density of an aluminum block? Explain your answer. Once the density of aluminum is calculated, what data will you need to determine the thickness of the aluminum foil? • Remember: D=m/V and V = L*W*H (H is the thickness of the aluminum foil) Knowing that D=m/V and V = L*W*H , how can you rearrange the formulas to calculate the thickness of the aluminum foil. So….what do you need to know? So procedures… • Glassware is being used so…. goggles • Levels of precision for out instruments?? Balance _________________ Grad cylinder: ____________ Ruler: ___________________ • Note: cm3 =mL of water at the same temperature • Formula for average: Ave= (D1 +D2)/2 • Water displacement method: demo • Math: ESSR! Box your final answer! Clean up All aluminum blocks get dried and returned to teacher. Graduated cylinders, rulers and balances get returned to side of lab. Return to seat to work on lab. Goggles are removed only upon teacher announcement that room is clean