Presentation Transcript

1. Lab Skills Focus: Filtration
2. Chemical Equation MgSO4 + Na2CO3 → MgCO3(s) + Na2SO4 magnesium + sodium→magnesium + sodium sulfate carbonatecarbonatesulfate Clear liquid Word Equation
3. When solutions of two soluble salts are mixed, a solid may form. This solid is called a precipitate. and the reaction is called a precipitation reaction. Precipitation reactions are used to make insoluble salts. In this example the soluble salts are magnesium sulfate and sodium carbonate, and the insoluble salt formed is magnesium carbonate.
4. Law of Conservation of Mass
5. Instructions 1. Measure 5 g of baking soda and put into a flask. 2. Measure 20 mL of vinegar and carefully pour it into a balloon. 3. Carefully attach the balloon to the top of the flask without spilling the vinegar into the flask. 4. Place the flask with balloon on a weighing scale and record the mass of the system. 5. Tip the vinegar from the balloon into the flask and record your observations. 6. Measure the mass of the system after the reaction. 7. Pop the balloon and measure the mass again.
6. Summary Explain whether your results support the Law of Conservation of Mass.

7. Endothermic and Exothermic Reactions(Heat Change)

8. Exothermic and EndothermicReactions An energy change accompanies the forming or breaking of a bond between atoms in a molecule. O Energy is released (produces heat) when a bond forms Exothermic o Energy is absorbed from the surroundings to break the bonds in a molecule Endothermic
9. In your notebook: Draw a diagram of the set-up Make a data table Make a graph Calculate temperature change as a function of time
10. Explore Lab 1: Energy change Endothermic Reaction Make a blank table for recording results. Pour 25 mL of acetic acid into a 400 mL beaker. Record the temperature of acetic acid as the starting temperature. Keep the thermometer in the acetic acid and add 5 g of baking soda into the beaker. Watch the thermometer carefully and record the time for each degree Celsius drop. Graph the rate of temperature change. Calculate the rate of temperature change.
11. Calculating Rate of temperature change Maximum ⁰C – Minimum ⁰C = Rate of temperature change Total Time (sec)
12. Explore Lab: Energy change Endothermic Reaction Summary: Explain how this lab shows a chemical reaction. How does the graph show that the reaction is endothermic? Explain.
13. Endothermic reaction results: Starts at around 25 degrees C and ends at around 21 degrees C Happens within about 2 minutes http://www.youtube.com/watch?v=MyAzjSdc3Fc Endothermic Reaction
14. Exothermic Reaction: Oxidation of steel wool Explore Lab 2: Energy change Put 8 grams of wool into a 400 mL beaker. Add enough acetic acid to completely cover the wool. 3. Swirl for 2 minutes to remove the protective coating. 4. Pour the acetic acid into a waste beaker. 5. Quickly cover the beaker with Parafilm. 6. Insert a thermometerthrough the film and into the steel wool. 7. Record the time for each degree Celsius rise and follow the temperature/time profile through a 5 degree change.
15. Exothermic reactions The reaction produces heat. In this reaction vinegar is used to remove the protective coating from steel wool, allowing it to rust. When the iron combines with oxygen, heat is released.
16. Exothermic Reaction: Oxidation of steel wool Summary: Explain how this lab shows a chemical reaction. On the same graph (endothermic), show a graph of temperature change as a function of time. How does the graph show that the reaction is exothermic? Explain.
17. Exothermic Reaction: Oxidation of steel wool Applying the Law of Conservation of Mass: How many atoms of Oxygen is needed to react with 4 atoms of Iron to form 2 units of Iron oxide? 4 Fe+ ___ O2 2 Fe2O3 4Fe+ 3O2 2Fe2O3 4 Fe + 6 O = 4 Fe + 6 O