# Will the ball float on liquid mercury? 1. The ball floats on liquid mercury!

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<ul><li> Slide 1 </li> <li> Will the ball float on liquid mercury? 1 </li> <li> Slide 2 </li> <li> The ball floats on liquid mercury! </li> <li> Slide 3 </li> <li> Why did it happen???? Mercury density = 13600kg/m 3 The balls density = 11340kg/m 3 </li> <li> Slide 4 </li> <li> 4 SI Units Density </li> <li> Slide 5 </li> <li> Must (Pass) Should (Merit) Could (Distinction) Be able to calculate density from given values. Be able to suggest the order of liquids in a density ladder. Be able to explain a density ladder. Be able to calculate the density of regular objects by experimental means. Be able to manipulate and use the density triangle. Be able to calculate the density of irregular objects by experimental means. 5 </li> <li> Slide 6 </li> <li> lecturePLUS Timberlake6 Density Density compares the mass of an object to its volume D = mass = g or g volume mL cm 3 Note: 1 mL = 1 cm 3 </li> <li> Slide 7 </li> <li> What is Density? Density is the Mass per unit Volume WoodWaterIron 1 cm 3 1 cm 3 1 cm 3 If you take the same volume of different substances, then they will weigh different amounts. 0.50 g1.00 g8.00 g Q) Which has the greatest mass and therefore the most dense? IRON </li> <li> Slide 8 </li> <li> Density = Mass Volume g or kg cm 3 or kg 3 gcm -3 or kgm -3 = m V Density Equation: m V </li> <li> Slide 9 </li> <li> Example: Q) Liquid water has a density of 1000kgm -3, while ice has density of 920kgm -3. Calculate the volume occupied by 0.25kg of each. Density Equation: V = m = 0.25 = 0.000250m 3 1000 V = m = 0.25 = 0.000272m 3 920 </li> <li> Slide 10 </li> <li> lecturePLUS Timberlake10 Learning Check D1 Osmium is a very dense metal. What is its density in g/cm 3 if 50.00 g of the metal occupies a volume of 2.22cm 3 ? 1) 2.25 g/cm 3 2)22.5 g/cm 3 3)111 g/cm 3 </li> <li> Slide 11 </li> <li> lecturePLUS Timberlake11 Solution 2) Placing the mass and volume of the osmium metal into the density setup, we obtain D = mass = 50.00 g = volume2.22 cm 3 = 22.522522 g/cm 3 = 22.5 g/cm 3 </li> <li> Slide 12 </li> <li> 12 Volume Displacement A solid displaces a matching volume of water when the solid is placed in water. 33 mL 25 mL </li> <li> Slide 13 </li> <li> lecturePLUS Timberlake13 Learning Check What is the density (g/cm 3 ) of 48 g of a metal if the metal raises the level of water in a graduated cylinder from 25 mL to 33 mL? 1) 0.2 g/ cm 3 2) 6 g/m 3 3) 252 g/cm 3 33 mL 25 mL </li> <li> Slide 14 </li> <li> lecturePLUS Timberlake14 Solution 2) 6 g/cm 3 Volume (mL) of water displaced = 33 mL - 25 mL= 8 mL Volume of metal (cm 3 ) = 8 mL x 1 cm 3 = 8 cm 3 1 mL Density of metal = mass = 48 g = 6 g/cm 3 volume 8 cm 3 </li> <li> Slide 15 </li> <li> 15 Learning Check3 Which diagram represents the liquid layers in the cylinder? (K) Karo syrup (1.4 g/mL), (V) vegetable oil (0.91 g/mL,) (W) water (1.0 g/mL) 1) 2) 3) K K W W W V V V K </li> <li> Slide 16 </li> <li> 16 Solution (K) Karo syrup (1.4 g/mL), (V) vegetable oil (0.91 g/mL,) (W) water (1.0 g/mL) 1) K W V </li> <li> Slide 17 </li> <li> DENSITY OF A REGULAR SOLID Find the Mass of the solid on a balance. Measure the three lengths and calculate the Volume. (ie V = l x w x h ) Calculate the Density. 4.0 cm 2.0 cm 3.0 cm = m = 240 =10.0 g/cm 3 V 24 m = 240 g </li> <li> Slide 18 </li> <li> DENSITY OF AN IRREGULAR SOLID Find the Mass of the solid on a balance. Fill the Measuring Cylinder with Water to a known Volume. Add the Object. Work out the Volume of Water that is displaced. Calculate the Density. 50 cm 3 80 cm 3 m = 360 g = m = 360 =12.0 g/cm 3 V 30 </li> <li> Slide 19 </li> <li> DENSITY OF AN IRREGULAR SOLID OR use a Eureka Can to find the Volume. Find the mass of the solid on a balance. Add water until just overflowing. Place a Measuring Cylinder under the spout. Add the Object. Collect the Water and read off the Volume. Calculate Density m = 440 g 40.0 cm 3 = m = 440 =11.0 g/cm3 V 40 </li> <li> Slide 20 </li> <li> 20 Learning Check You have 3 metal samples. Which one will displace the greatest volume of water? 1 2 3 Discuss your choice with another student. 25 g Al 2.70 g/mL 45 g of gold 19.3 g/mL 75 g of Lead 11.3 g/mL </li> <li> Slide 21 </li> <li> 21 Solution 1)25 g Al x 1 mL = 9.2 mL 2.70 g 25 g Al 2.70 g/mL </li> <li> Slide 22 </li> <li> Pre-Lab How do you correctly read a graduated cylinder? What techniques can you use to measure the volume of an irregularly shaped object? What tips should you remember? How do you take the slope of a line? How is percentage error defined? Name the two general types of mathematical relationships between variables to be investigated in this lab What safety precautions must be taken for this lab 22 </li> <li> Slide 23 </li> <li> Materials Rock sample Balance Graduated cylinder(s) 23 </li> <li> Slide 24 </li> <li> Procedure Choose equipment to make and record all measurements as accurately and precisely as possible. Be sure to record the correct number of digits for your data. 1.Obtain 2 rock samples 2.Make sure the samples are dry and clean. Obtain their masses. Remember the uncertainty 3.Measure the volume of the rock using the volume displacement method 24 </li> <li> Slide 25 </li> <li> 4. Repeat method 2 and 3 and obtain an average 5. Calculate the volume of the rock. 6.Repeat for the second sample. 25 </li> <li> Slide 26 </li> <li> Results Data table and calculations 26 Initial Vol (ml) Final Vol (ml) Calculated volume (ml) Mass (g) Sample 1 Trial 1 Trial 2 Average Sample 2 Trail 1 Trail 2 Average </li> <li> Slide 27 </li> <li> More Calculations 1.Make a single table using mass and volume, density for all samples. Display the formula and show all working. Ensure all units are correctly displayed. 2.Obtain the class data for each group for each sort of rock sample and make another table, showing mass, volume, as well as the computation of mass x volume and mass/volume. Use the appropriate units. 27 </li> <li> Slide 28 </li> <li> 3.Your graph will show a scatter of points, draw a line of best fit. 4.Look at the data/calculations table, which is constant; mass x volume OR mass/vol ? 5.What type of relationship was found in this lab? Hint: If A/B is constant, then there is a direct relationship. If AxB is constant then there is an inverse relationship. 6.Using the above data, explain what the gradient of the line represents? 28 </li> <li> Slide 29 </li> <li> 7.Calculate the gradient of the line. You can choose any two points on a line to calculate slope, but it is best to choose them far apart. 8.Accurately calculate your gradient. Write your final slope as a decimal, to two decimal places. Dont forget units!! 29 </li> <li> Slide 30 </li> <li> Discussion: Answer the following questions. 1. Compare your calculated gradient from the class results to your calculated density from your own results. What is the error margin? 2.Should a density graph go through the point (0,0)? Why or why not? 3.Would you get the same values of slope if you just counted the number of grid lines in the rise and run (ignoring the scales on your graph)? Give one example. 30 </li> <li> Slide 31 </li> <li> 4.Why must the samples be clean and dry to start? 5.If I randomly picked two pure solid substances in the room, is it likely that they would have the same density? If I could take any size piece of either, could I make them have the same density? Comment on your answers. 6.If you were given another rock sample, would you rather know its mass or its density if you wanted to find out what kind of rock it is. Explain. 31 </li> <li> Slide 32 </li> <li> 7.Would the presence of an air bubble stuck on the submerged rock tend to make the density too high or too low? Explain. 8.Discuss any experimental errors that could of lead to the inaccuracies in this lab. 9.What improvements could you put in place to increase the accuracy of your results. Conclusion: 32 </li> <li> Slide 33 </li> <li> Lab Report Due: When you hand in your full lab report, make sure the pre-lab is on the top. For this lab make sure your graph is the last page of the report. Due Date: Wednesday Sept 19 th. All questions will be on the PowerPoint on teacherweb. 33 </li> </ul>

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