Presentation on theme: "Matter and Energy. Matter has mass occupies space Solid - definite volume and shape Liquid - definite volume and takes shape of container Gas - compressible."— Presentation transcript:
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 ZElement - cannot be broken down into other substances by chemical means Zexamples - oxygen, carbon, calcium ZCompounds - chemical combination of elements that has a definite composition Zexamples - water (H 2 O), hydrogen peroxide (H 2 O 2 ), carbon dioxide (CO 2 )
Mixtures ZMixture - something with variable composition Zexamples - wood, koolaide, coffee ZHomogeneous - look the same throughout (a solution) Zexamples - air, brass ZHeterogeneous - different parts have different composition Zexamples - pizza, chocolate chip ice cream ZCan be separated using physical properties or changes Zexamples - distilling, filtering, etc.
Energy, Temperature and Heat ZEnergy - the capacity to do work ZWe can use energy from propane (via burner) to change the temperature of something (do work on the molecules)
ZHeat - a flow of energy due to temperature difference ZEnergy is transferred from warmer molecules (moving faster) to cooler molecules (moving slower) ZExothermic - when a process results in heat being given off (a match burning) ZEndothermic - when a process results in heat being absorbed (melting ice)
Calculating Energy Changes ZThe amount of energy (heat) required to raise the temperature of one gram of water by one Celsius degree - calorie (or joule) Z1 cal = 4.184 J ZEnergy required = energy per gram of substance times actual grams of substance times actual temperature change ZEnergy needed = energy per gram x # grams x temp change
Practice Problem Determine 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
ZSpecific heat capacity (specific heat) - the amount of energy required to raise the temperature of one gram of a substance by one Celsius degree ZTable 3.2 p. 70
Energy required = Q Specific heat = s Mass in grams = m Change 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 B Each 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.