Daily TAKS Connection: Density, Viscosity, and Buoyancy IPC(7): The student knows relationships exist between properties of matter and its components. The student is expected to: (A) Investigate and identify properties of fluids including density, viscosity, and buoyancy.

Day 1 Instructions: Materials: Foldable handout (2 pages) Scissors Pen Construct a folded book foldable and title “Density, Buoyancy and Viscosity” Materials: Foldable handout (2 pages) Scissors Pen Colored pencils/crayons Instructions: Hamburger fold the foldable handouts Cut 2 cm slits from the edges of the fold of the handout that has page 2 (as marked) Cut along the fold line of the other sheet of paper beginning and ending about 2 cm from each end (as marked). Burrito fold and insert paper from step 2 into the hole and open, forming a book.

Day 2 notes Record the following notes on page 1 (Density/Buoyancy) of your foldable: Density determines an object’s buoyancy (object sinks or floats) The more dissolved solids in a liquid the greater the density of the liquid. The greater the density of the liquid, the greater the buoyant force exerted on an object immersed in it (the easier the object floats) Air bubbles make things buoyant (float)

Question 1 Swimmers find that they can float more easily in the ocean than in a freshwater lake. The most likely reason for this phenomenon is that the – a. viscosity of lake water is greater than that of ocean water b. density of ocean water is higher than that of lake water c. temperature of lake water is lower than that of ocean water d. mass of ocean water is greater than that of lake water Answer: b; density determines whether an object sinks or floats.

Question 2 A sample of water from a river has a greater density than a sample of distilled water. Which is the best explanation for the difference in density? a. Rivers have kinetic energy. b. Rivers contain dissolved minerals. c. Distilled water has a neutral pH. d. Distilled water can contain dissolved gases. Answer: b; dissolved minerals (salts) increases density.

Question 3 Today, the observation that an air bubble in water rises to the surface is explained by the principle of — a. viscosity b. interference c. buoyancy d. polarity Answer: c

Question 4 A bar of soap is produced that sinks to the bottom of a container of water. Which of these processes could cause the bar of soap to float in water? a. Making grooves in the surface of the thick paste b. Letting the thick paste sit for four days c. Adding air bubbles to the thick paste d. Chilling the mold filled with the thick paste Answer: c

Day 3 notes Record the following notes on page 2 (More Density) of your foldable: density is constant, regardless of how much material is present (example: a drop of pool water has the same density as a gallon of pool water and has the same density as pool full of water) The density of water is 1 g/ml (materials w/ a density <1 float; materials w/ a density >1 sink)

Day 3 notes continued…. Solid Liquid Gas Most dense Less dense Least dense density of solids > density of liquids > density of gases

Question 5 A block of maple wood with a volume of 405 cubic centimeters and a density of 0.67 g/cm3 is sawed in half. The density of the two smaller blocks is now — a. one-fourth the original density b. two times the original density c. one-half the original density d. the same as the original density Answer: d; density is the same regardless of the amount of material present.

Question 7 The table shows properties of four liquids that are insoluble in water. If the four liquids are poured into an Erlenmeyer flask containing water, which liquid will form a layer below the water? a. Q b. R c. S d. T Answer: A; materials with a density greater than 1 g/mL (density of water) will sink.

Question 6 Compared to 150 g of gaseous carbon dioxide, 150 g of liquid carbon dioxide has greater — a. volume b. mass c. temperature d. density Answer: d; liquids are more dense than gases

Day 4 notes Turn to page 3 of foldable, “Even More Density” Record formula for density from the formula chart in your notes on page 3. Copy the information from the following chart into your foldable. Measurement Units Lab apparatus used Mass Grams Laboratory balance (sketch a balance here) Volume Milliliters Graduated cylinder (sketch a graduated cylinder here)

Question 8 What is the density at 20C° of 12.0 milliliters of a liquid that has a mass of 4.05 grams? a. 0.338 g/mL b. 16.1 g/mL c. 2.96 g/mL d. 48.6 g/mL Answer: a; density = 4.05/12

Question 9 Which of the following objects will float on water? a. c. d. Answer: d; calculate densities of each object – density less than 1 will float on water

m D v Day 5 notes Calculation Triangle Turn to page 4 of foldable “Still More Density” Copy formula onto the calculation triangle use calculation triangle to write formula needed to solve for mass use calculation triangle to write formula needed to solve for volume Calculation Triangle m D v

Question 10 What is the mass of a 250.00 mL sample of seawater with a density of 1.025 g/mL? a. 243.9 g b. 256.25 g c. 250.0 g d. 312.5 g Answer: b; mass = 1.025 x 250

Question 11 A sample of an element has a mass of 75.0 g and a density of 1.25 g/mL. What is the volume in milliliters of the sample? Record your answer to the nearest tenth. Answer: volume = 75/1.25 = 60 mL

Question 12 A 250 mL quantity of vanilla ice cream has a mass of 200 grams. The manufacturer then bubbles air into the ice cream so that its volume increases by 150 mL. What is the ice cream’s approximate final density? a. 0.30 g/cm 3 b. 0.80 g/cm 3 c. 0.50 g/cm 3 d. 1.30 g/cm 3 Answer: c; First, determine final volume is 250 + 150 = 400 mL. Then calculate density = 200/400 = 0.5

Day 6 notes Ex: Warm honey flows more quickly than cold honey. Turn to page 5 of foldable, “Viscosity” Fluids with low viscosity flow quickly Fluids with high viscosity flow slowly heating a fluid decreases viscosity; cooling a fluid increases viscosity Ex: Warm honey flows more quickly than cold honey.

Question 13 Students in a chemistry lab measure the time it takes four different 50 mL solutions to pass through a hole in the bottom of a cup. Which of the following properties of the solutions is most likely being measured? a. Buoyancy b. Viscosity c. Mass d. Volume Answer: b (More impact with students if you show this as a quick demo)

Question 14 As the viscosity of a liquid decreases, the liquid — a. conducts electricity b. evaporates more quickly c. pours more quickly d. forms a precipitate Answer: c

Question 15 Brown sugar consists of crystals of white sugar coated with molasses. If brown sugar hardens, it can be softened by heating. The most likely reason brown sugar softens when heated is that heat — a. increases the moisture of sugar b. increases the density of sugar c. decreases the volume of molasses d. decreases the viscosity of molasses Answer: d