# Activity 10 Follow-up Were there differences in your results from one group to another? Why did we use the average to compare to table 3 in activity 9?

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Activity 10 Follow-up Were there differences in your results from one group to another? Why did we use the average to compare to table 3 in activity 9?

Analysis: 1.Based on your density calculations and the data on Student Sheet 10.1, what are the two metallic solids from the unlabeled mixture? Provide evidence from the activity to support your answer. Aluminum and zinc This is because the density I calculated for the light gray cylinder was __ and the average from the group results was __ Discuss the results for the dark gray cylinder

3.Review your answer to Question 1 of Activity 3, A Plan to Separate the Mixture. How close was your prediction about the number of substances in the unlabeled mixture? Explain why you may have considered the HDPE sample to be different substances or why you counted the light and dark gray cylinders as one substance Discuss your increase in confidence to determine the amount of substances based on the evidence gathered

4.Reflection: What are the three most important things you learned in this unit about identifying and studying materials scientifically? Aware of safety precautions Assume a substance is hazardous Wear protective eyewear and gloves Etc. Understand some methods used to identify materials Corrosive, flammable, reactive, toxic Physical properties

Density of Water

Finding the Density of Water Do different amounts of water have the same density? What two things do you need to know in order to find the density of water? How can you measure a volume of water? How can you measure the mass of water?

Discussion Water molecules have the same mass and size, are packed pretty close together, and are spread evenly throughout. Since the water is the same throughout an entire sample, the density is the same for any amount of water.

So, if a volume of water has a certain mass, twice the volume will have twice the mass, three times the volume has three times the mass, etc. No matter what size sample of water you measure, the relationship between the mass and volume will always be the same. Because D=m/v, the density is the same for any amount of water.

Density of Water The excepted value for the density of water is 1 g/cm 3 Remember 1 cm 3 = 1 mL

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