Matter and Energy

Matter

• has mass• occupies space• Solid - definite volume and shape

• Liquid - definite volume and takes shape of container

• Gas - compressible and takes shape of container

Physical Properties and Changes- Properties: characteristics observed about a substance

- examples - color, odor, volume, density, melting point

- Changes: do not affect the composition of the substance

- Examples - melting, boiling, cutting

Chemical Properties and Changes- Properties: refer to its ability to form new substances

- examples - burns, digests, rusts

- Changes: affect the composition of the substance

- examples - burning, digesting, rusting

Elements and Compounds

Element - cannot be broken down into other substances by chemical means

examples - oxygen, carbon, calcium

Compounds - chemical combination of elements that has a definite composition

examples - water (H2O), hydrogen peroxide (H2O2), carbon dioxide (CO2)

MixturesMixture - something with variable composition

examples - wood, koolaide, coffeeHomogeneous - look the same throughout (a solution)

examples - air, brassHeterogeneous - different parts have different composition

examples - pizza, chocolate chip ice cream

Can be separated using physical properties or changes

examples - distilling, filtering, etc.

Energy, Temperature and HeatEnergy - the capacity to do work

We can use energy from propane (via burner) to change the temperature of something (do work on the molecules)

Heat - a flow of energy due to temperature difference

Energy is transferred from warmer molecules (moving faster) to cooler molecules (moving slower)

Exothermic - when a process results in heat being given off (a match burning)

Endothermic - when a process results in heat being absorbed (melting ice)

Calculating Energy ChangesThe amount of energy (heat) required to raise the temperature of one gram of water by one Celsius degree - calorie (or joule)

1 cal = 4.184 J Energy required = energy per gram of

substance times actual grams of substance times actual temperature change

Energy needed = energy per gram x # grams x temp change

Practice ProblemDetermine the amount of energy as heat that is required to raise the temperature of 1.0 L of water from 25.0* C to boiling (100.0* C). Give the answer in joules and calories.

1.0 L of water = 1.0 kg of water

1.0 kg of water = 1000. kg of water

1.0 kg * 1000. g =1000. g water-------- --------- 1 1 kg

4.184 J x 1000. g x 75.0* C = 314 000 J (314 kJ)

------- --------g *C 1

314 000 J x 1 cal = 7.50 x 104 cal (75.0 kcal)

----------- ---------- 1 4.184 J

Specific heat capacity (specific heat) - the amount of energy required to raise the temperature of one gram of a substance by one Celsius degree

Table 3.2 p. 70

Energy required = QSpecific heat = sMass in grams = mChange in temp in C = delta T

Q = s x m x delta T

Practice Problem

Determine the amount of energy as heat that is required to raise the temperature of a 10.0 g sample of aluminum from

25 *C to 58 *C. Answer in joules and calories.

0.89 J x 10.0 g x 33 *C = 294 J

--------g *C

294 J x 1 cal = 70. Cal

------- --------- 1 4.184 J

Lab 9 - Calorimetry

The energy lost by one part of the system (hot water or hot metal) is gained by another part of the system (cold water).

Read lab introduction.Read lab procedures.Do Pre-Lab questions (we will do #2 together).Part A

Each lab group will do one time only - we will that all of the calorimeters will have the same value, and use data from all group to come up with a calorimeter constant.

Part BEach lab group will do three determinations of specific heat capacity for their metal samples.

Each lab group will do one determination of specific heat of glass.

Answer the questions 1-4 at the end of the lab.

Figure percent error for your measurement of specific heat of the metal sample.

Answer the questions.