Drill How should we set up a lab notebook? What should we include, etc?

General Tips for Lab Notebook Leave a blank page or two at the beginning of your notebook so you can create a Table of Contents Number pages Use permanent ink Draw only a single line through all errors written, so they still can be seen Record all observations and explanations of why they happened Be as descriptive as possible with titles and headings for your experiments; for example do not write "Chemical Synthesis," instead write "Preparation of Alum"

Agenda Notebook Set up Calorimetry Problems Lab – Proc B Lab Table

Calorimetry Notes

Calorimetry Calorimetry is the study of the heat released or absorbed during physical and chemical reactions For a certain object, the amount of heat energy lost or gained is proportional to the temperature change

Calorimetry A calorimeter can be a thermos, Styrofoam cup, or any container that minimizes heat loss The size of the temperature change depends on: How much heat is released or absorbed The heat capacity of the surroundings

Specific Heat Review Specific Heat – energy needed to raise 1 gram of a substance by 1˚C Specific heat is a physical property Liquid water’s specific heat is 4.184 J/gºC q = (m) x (c) x (Δ T) If a hot object is put in water in a calorimeter, then the heat absorbed by the water is equal to the heat given off by the substance. ΔH of water = - ΔH of substance

Because of the law of conservation of matter … qmetal= -qaq

qmetal = -qaq mmcmDTm = -mwcwDTw -mwcwDTw cm = mmDTm

Practice Problem 1 Example: You put 103.0 g of aluminum in 100.0 grams of boiling water. The water temperature changes from 100.0ºC to 90.0ºC, while the aluminum temperature goes from 25.0ºC to 70.0ºC. What is the specific heat of aluminum?

Practice Problem 1 qmetal = -qaq H2O Al = -4635 g°C(c) = -4180 J (100.0g)(4.184J/g°C)(90.0-100.0 C) -4635 g°C(c) = -4180 J c = 0.902 J/g°C

Practice Problem 2 A 46.2 g sample of copper is heated to 95.4ºC and then placed in a calorimeter containing 75.0 g of water at 19.6ºC. The final temperature of both the water and the copper is 21.8ºC. What is the specific heat of copper?

Practice problem 2 qcu = mcΔT qh2o = mcΔT mcΔT = qcu = qh2o = mcΔT (46.2 g) ccu (73.6 C) = (75 g) (4.184 J/gC) (2.2C) ccu = 0.20 J/g°C

Another type… What if something dissolves in the water? What happens to the total mass??? You add them up! The whole solution increases (or decreases) in heat.

Drill A chemistry student dissolves 4.51 grams of room temperature sodium hydroxide in 100.00 g of water at room temperature, 19.5°C. As the sodium hydroxide dissolves, the temperature of the solution increases to 31.7°C. Determine the heat of solution of the sodium hydroxide in J/mol.

Answer 47.3 kJ/mol

Calorimetry Lab