Week 1 Chemistry Worksheet

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Northeastern University *

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131

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Chemistry

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Dec 6, 2023

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docx

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College Chem I CHE 131 Week 1 Worksheet Packet States of Matter 1) Describe the difference between physical change and chemical change. Physical Change: when a substance undergoes a physical change, its composition remains the same despite its molecules being rearranged. It is a temporary change. It only affects physical properties, i.e., shape, size, etc. Examples of physical change: freezing of water, melting of wax, boiling of water, etc. Chemical Change: when a substance undergoes a chemical change, its molecular composition is changed entirely. Thus, chemical changes involve the formation of new substances. A chemical change is permanent. Chemical changes both physical and chemical properties of the substance including its composition. Examples of chemical change: digestion of food, burning of coal, rusting, etc. 2) Decide if the following is a physical or chemical change. - Magnesium burns: chemical change. - Ice melts: physical change . 3) Decide if the following are physical or chemical property. - The density of acetyl silicic acid is 2.2 mg/mL: physical - Your three-century old silver fork tarnishes: chemical Metric Conversions – show your work – use extra paper if necessary 1. There are approximately 95 mg of caffeine in a cup of coffee. How many grams of caffeine is this? How many kg is it? Conversion Factors: 1 mg = 0.001 g 1 mg = 0.000001 kg 95 mg x 1 g / 1,000 mg = 0.095 g of caffeine 95 mg x 1 kg / 1,000,000 mg = 0.000095 kg of caffeine 2. X-rays have a wavelength of approximately 5 nm. How many meters is this? How many cm is this? Conversion Factors: 1 nm = 0.000000001 m 1 nm = 0.0000001 cm
5 nm x 1 m / 10 -9 nm = 5 x 10 -9 m 5 nm x 1 cm / 10 -7 nm = 5 x 10 -7 cm 3. The size of a typical red blood cell is approximately 8 µm. How many meters is this? How many km is this? Conversion Factors: 1 µm = 0.000001 m 1 µm = 0.000000001 km 8 µm x 1 m / 10 -6 µm = 0.000008 m 8 µm x 1 km / 10 -9 µm = 0.000000008 km 4. A swimming pool has a volume of 216,000 L. How many mL is this? How many cm 3 is this? Conversion Factors: 1 L = 1000 mL 1 L = 1000 cm 3 216,000 L x 1000 mL / 1 L = 216,000,000 mL 216,000 L x 1000 cm 3 / 1 L = 216,000,000 cm 3 5. The distance from Bedford to Lowell is 12 miles. How many meters is this? How many mm is this? Conversion Factors: 1 mile = 0.621 km 1 mile = 6.21 mm 12 mi x 1 km / 0.621 mi = 19.3 km 19.3 km x 1000 m / 1 km = 19,300 m 19,300 m x 1000 mm / 1 m = 19,300,000 mm 6. Using the dosage chart below, how much Tylenol should be given to a 15.6 lb infant? Patient weight (kg) Dosage 2.7 – 5.4 1.25 mL 5.5 – 7.9 2.5 mL 8.0 – 10.9 3.75 mL 11 – 15.9 5 mL
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