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IAN pg. 50. REACTIONS. Single Replacement, Exothermic, Endothermic. Single Replacement Reactions. SRR: reaction where a free element replaces a less active element in a compound SR Reactions always start and end with an element and a compound Example: Zn + CuSO 4 ZnSO 4 + Cu.
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IAN pg. 50 REACTIONS Single Replacement, Exothermic, Endothermic.
Single Replacement Reactions • SRR: reaction where a free element replaces a less active element in a compound • SR Reactions always start and end with an element and a compound • Example: Zn + CuSO4 ZnSO4 + Cu
Exo-/Endo- Thermic • Chemical Reactions always involve energy: • Exothermic: energy is released • Endothermic: energy is absorbed • Endothermic reactions usually “feel cold”
Lab Activity: SRRPart A • Pour about 1/2 inch of HCl into each of the 4 test tubes. • Place one of the metals into a test tube. • Feel the bottom of each tt as the reaction proceeds and note any other observations in the data table. Observe for 5 minutes. • When finished, pour off the acid into the sink and rinse any metals that are left with water and put them back into the tray.
IAN pg. 49. DATA TABLEPart A Do the observations UNDER the lab directions for Part A Hydrochloric Acid (HCl) mixed with: magnesium (strip):____________________ aluminum (tiny pieces):________________ zinc (pinch of powder):________________ copper (wire):_______________________
Lab Activity: Endothermic Reaction, Part B • Place small spoonfuls of calcium chloride (CaCl2) and baking soda into a baggie. • Put the powders into a corner of the baggie and twist it. • Into the other corner of the baggie, pour a small amount of water. • Press the air out and close the baggie. • Mix the contents together and feel the resulting mixture for temperature change. Record your observations.
OBSERVATIONSPart B Record what you observed when the calcium chloride, baking soda, and water were mixed inside the baggie (a closed system):
CONCLUSIONS • Write the single replacement reaction equations: a. Magnesium and HCl b. Aluminum and HCl c. Zinc and HCl • Were they exothermic or endothermic? • Which metal(s) are more active and which are less active than hydrogen? • Balance the SRR equation: AgNO3 + Cu Cu(NO3)2 + Ag
SRR Equations 2HCl + Mg MgCl2 + H2 6HCl + 2Al 2AlCl3 + 3H2 6HCl + 2Zn 2ZnCl3 + 3H2