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Block 77: F 5/9 and M 5/12. Warm Up: pg 4 #7b and 8b. Announcements: Sapling #29 due on Tuesday 5/13 Sapling #30 due on Thursday 5/15 Mole Project due NEXT WEEK: May 14 (B) or May 15 (A ) Test over Stoichiometry and thermochemistry next week on Thursday/Friday
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Block 77: F 5/9 and M 5/12 Warm Up: pg 4 #7b and 8b • Announcements: • Sapling #29 due on Tuesday 5/13 • Sapling #30 due on Thursday 5/15 • Mole Project due NEXT WEEK: May 14 (B) or May 15 (A) • Test over Stoichiometry and thermochemistry next week on Thursday/Friday • Stoichiometry retest must be done by Friday May 16
Changes in energy and specific heat • Specific Heat symbol is: c • It’s the amount energy needed to make 1 gram of a substance warmer by 1°C • The units are: • Every substance has a different specific heat • Basically we are calculating changes in amount of heat in a substance
Example Problem: I want to heat a hot tub from 22°C to 39°C. It holds 2.00 x 106 g of water. How much energy does that require? (the specific heat of water is 4.184 J/g•°C) Assignment: page 7 #1-4
water Thermometer Reaction chamber Insulated vessel Calorimeter: calori = energy meter = measuring device
Measuring Energy • Heat flows from the substanceto the calorimeter. • Calorimeters measure the changein temperature as a result of heat flow. Q gained by calorimeter = -Q lost by the item placed in the calorimeter
2450 g water Initial temperature 20°C Final temperature 80°C How much energy is in the pizza?
Example Problem: A sample of silver with a mass of 63.3 g is heated to a temperature of 384.4 K and placed in a container of water at 290.0 K. The final temperature of the silver and the water is 292.4 K. Assuming no heat loss, what mass of water was in the container? Water: mwater = __________ Ti = _____________ Tf = _____________ cwater = _____________ Silver: mAg = ___________________ Ti = _____________ Tf = _____________ cAg = ______________
Coming up and Homework • Next class: calorimetry lab---you may never eat cheetos again! • Mole project, saplings and test next week • Homework: • page 4 #7-8, • page 7 #1-4,