Activity 5: Investigating Weight Gain and Weight Loss

1. Activity 5: Investigating Weight Gain and Weight Loss

2. Conservation of Mass • (Except in nuclear reactions) the total mass of of the materials (solids, liquids, and gases) involved in any change in matter stays the same.

3. Tracing Matter Process Tool g g Gas Gas g g Liquid Liquid g g Process: Solid Solid Matter Inputs Matter Outputs

4. Wetting a Sponge g g Gas Gas 20 g g Liquid Liquid 30 g g Process: Solid Solid Matter Inputs Matter Outputs What is your prediction of the weight ofthe wet sponge?

5. Wetting Vermiculite g g Gas Gas 30 g g Liquid Liquid 40 g g Process: Solid Solid Matter Inputs Matter Outputs What is your prediction of the weight ofthe wet Vermiculite?

6. Wetting a Sponge g g Gas Gas 20 g g Liquid Liquid 30 g 50 g Process: Solid Solid Matter Inputs Matter Outputs Prediction that follows Conservation of Mass

7. Wetting Vermiculite g g Gas Gas 30 g g Liquid Liquid 40 g 70 g Process: Solid Solid Matter Inputs Matter Outputs Prediction that follows Conservation of Mass

8. Your Predictions and Measurements • When you measured the mass of the wet sponge and Vermiculite, how accurate were your predictions? • Do you think conservation of mass applies to wetting the sponge and Vermiculite? • Did the sponge and Vermiculite gain weight when you added water?

9. Drying a Sponge g g Gas Gas g g Liquid Liquid 50 g g Process: Solid Solid Matter Inputs Matter Outputs What is your prediction of the weight ofthe dry sponge? What happened to the mass of the water?

10. Drying Vermiculite g g Gas Gas g g Liquid Liquid 70 g g Process: Solid Solid Matter Inputs Matter Outputs What is your prediction of the weight ofthe dry Vermiculite? What happened to the mass of the water?

11. Drying a Sponge g 20 g Gas Gas g g Liquid Liquid 50 g 30 g Process: Solid Solid Matter Inputs Matter Outputs Prediction that follows Conservation of Mass

12. Drying Vermiculite g 30 g Gas Gas g g Liquid Liquid 70 g 40 g Process: Solid Solid Matter Inputs Matter Outputs Prediction that follows Conservation of Mass

13. Your Predictions and Measurements • When you measured the dry mass of the sponge and Vermiculite, how accurate were your predictions? • Do you think conservation of mass applies to drying the sponge and Vermiculite? • Did the sponge and Vermiculite lose weight when you dried them out?

14. A Student Drinking Water g g Gas Gas 600 g g Liquid Liquid 50.0 kg g Process: Student Student Matter Inputs Matter Outputs What is your prediction of the weight ofthe student after s/he drinks the water?

15. Watering Your Plants g g Gas Gas 10 g g Liquid Liquid 150 g g Process: Plant in cup Plant in cup Matter Inputs Matter Outputs What is your prediction of the weight ofthe cup, soil, and plants after watering?

16. A Student Drinking Water g g Gas Gas 600 g g Liquid Liquid 50.0 kg 50.6 kg Process: Student Student Matter Inputs Matter Outputs Prediction that follows Conservation of Mass

17. Watering Your Plants g g Gas Gas 10 g g Liquid Liquid 150 g 160 g Process: Plant in cup Plant in cup Matter Inputs Matter Outputs Prediction that follows Conservation of Mass

18. Final Discussion Questions • Look back at the questions you answered before starting this activity. Do you now have different answers to any of the questions? • Do you think that conservation of mass applied to all the changes that you measured? Why were the masses you measured before and after sometimes different? • You can see that the measured weight of something can vary a lot depending on how much water is in the system. How could we tell whether plants are gaining dry weight (not just water) when they grow?