Using chemistry vocabulary 1. Explain the concept of hot and cold. 2. In your own words explain what would happen to a pot of boiling water placed in the center of the room at the start of the block.
Density of water ONLY!!! 1.00g = 1.00mL 1kx = 1,000x
Energy is the capacity to do work, supply heat, or both (Gummy bear file)
Heat (q) – energy flows from warmer objects to cooler objects, SI unit is J = joule
4.18J = 1.00cal 4.18J = 1.00cal = ( heat to raise 1g water 1 o C)
Law of conservation of energy – energy is neither created nor destroyed Where does it go?
Thermochemistry study of energy changes that occur during chemical reactions and state changes
Chemical potential energy – energy stored in chemical bonds
Specific Heat (C) = the amount of heat it takes to raise the temperature of 1g of material 1K (1 o C) ΔT = (T final – T initial ) m=mass(g) q=heat(J) T= o C
How much heat is needed to raise the temperature of 750mL of water from 21 o C to 88 o C? (Answer in J and cal) p 508 Water = 4.18J/(g o C)
15kJ are supplied to a 750g iron pan. What will be the temperature change of the pan?
System is a part of the universe you focus on. The surroundings are everything outside the system (rest of the universe).
Entropy - Disorder - randomness of a system Enthalpy (H)– the heat content of a system exothermic – heat exits endothermic – heat enters
Endothermic
exothermic
Puzzle Puzzle Calorimetry – measurement of a heat change
heat change ΔH = -mCΔT m=mass C=specific heat ΔT=(Final Temp− Initial Temp)
A 375g block of iron is placed in 115g of water and the temperature of the water changes from 11.5 o C to 35.1 o C. What is the original temperature of the iron block? Water = 4.186J/g Iron = 0.46J/g
A hot (225 o C) 215g block is placed in 179mL of water at 22 o C. The water temperature raises to 49 o C (the block cools to 49 o C). What is the specific heat of the block?
a heat term is included in a chemical equation = thermochemical equation CaO + H 2 O Ca(OH) kJ (-ΔH) exothermic the system lost heat
CaO + H 2 O Ca(OH) kJ (-ΔH) exothermic, the system lost heat heat is a product released to its surroundings
2NaHCO kJ Na 2 CO 3 + H 2 O + CO 2 (+ΔH) Endothermic, the system gained heat heat is a reactant
2NaHCO kJ Na 2 CO 3 + H 2 O + CO 2 How much heat is needed to convert 454g of NaHCO 3 ?
2NaHCO kJ Na 2 CO 3 + H 2 O + CO 2 How much heat is needed to convert 454g of NaHCO 3 ?
2NaHCO kJ Na 2 CO 3 + H 2 O + CO 2 How much heat is needed to convert 454g of NaHCO 3 ?
2NaHCO kJ Na 2 CO 3 + H 2 O + CO 2 How much heat is needed to convert 454g of NaHCO 3 ?
2H 2 + O 2 2H 2 O + 470kJ How much heat will be released if 25g of H 2 is reacted with oxygen?
2H 2 + O 2 2H 2 O + 470kJ How much heat will be released if 25g of H 2 is reacted with oxygen?
2NaHCO kJ Na 2 CO 3 + H 2 O + CO 2 How many joules of heat are needed to convert g of NaHCO 3 ?
2NaHCO kJ Na 2 CO 3 + H 2 O + CO 2 How many joules heat is needed to convert 750g of NaHCO 3 ? 575,893J = 50pts kJ = 45pts 1,151kJ or 1,100,000J = 40pts Tried = 25pts Nothing = 0pts
A 575g iron pan is placed on the stove top with 1250mL of water in it at 18 o C. How much heat energy must the stove give off to heat the pan and water to 99 o C in order to cook some Ramen Noodles? Water =4.186J/g o C Iron = 0.46J/g o C (Mmmmm..mmmm Ramen noodles)
A 575g iron pan is placed on the stove top with 500mL of water in it at 18 o C. How much heat energy must the stove give off to heat the pan and water to 100 o C in order to cook some Ramen Noodles? Water =4.186 o C Iron = 0.46J/g o C water =?J iron = ?J total = ?J or ?kJ
CaO (s) + H 2 O (l) Ca(OH) 2 (s) kJ How much heat is released if 168g of CaO is reacted with water?
Homework out ½ sheet of paper Get Safety goggles Write your name on your paper. Predict the temperature of ice water in Celsius and o F. Explain (1-2 sentences) why you made your prediction.
Measure the temperature of the ice water mix. Record the measurement. Predict the temperature of the ice water mix after the deicer has been added. Explain (2- 3 sentences)
Record the actual temperature after the deicer has been added. What do you think happened… Explain (2- 3 sentences).
Predict what will happen to the water in the test tube (below). Explain (2-3 sentences). Add a test tube with a small amount of water to your solution. Stir.
Heat and Changes of State Energy is absorbed or released when matter changes state.
When ice melts, it absorbs energy from the surroundings. As melting proceeds, the liquid and solid water remain at the same temperature until all of the ice has melted.
ADDING ENERGY: When adding energy, 1 of 2 things happens: 1.) Temperature Increases OR 2.) Phase Changes. NOT AT THE SAME TIME!!!!!!!!!!!!!!!!!!! Draw Phases, i.e, Temp vs Energy Graph below of ice turning to steam and show two plateaus.
For (l) (g), an endothermic process, molar heat of vaporization, H vap For water, H vap = 40.7 kJ
for (g) (l) condensation, exothermic molar heat of condensation. For water H cond = kJ
How much energy is needed to convert 25g of water at o C into 25g of steam at o C? (state change)
How much energy is needed to convert 25g of water at 23.0 o C into 25g of steam at o C? (state change)
Heat of solution dissolving NaOH in water. H 2 O + NaOH (s) Na + (aq) + OH - (aq) H soln = kJ/mol
Write a procedure (with data and calculations ) for the creation of 100mL of a 0.125M MgSO 4 (MgSO 4. 7H 2 O) solution. Create your solution in a 100mL graduated cylinder and bring it to me.
Specific Heat capacity (specific heat) – the amount of heat it takes to raise the temperature of 1g of material 1K(1 o C) Water = 4.186J/g Iron = 0.46J/g What would heat up faster water or iron?
After this reaction will the system be cooler? After the reaction will the reactants be closer to each other?
When 250 J of heat is added to 15 g of X at 21 C, the temperature increases to 85 C. What is the specific heat of the X?
If the mixture gets colder is the reaction gaining or releasing heat? 2 solutions react and the temperature of this 125mL mixture (assume 100% water) drops 3.5 o C. How much energy was gained by this reaction?