Presentation on theme: "Matter is the part of the universe that has mass and volume Energy is the part of the universe that has the ability to do work Chemistry is the study."— Presentation transcript:
Matter is the part of the universe that has mass and volume Energy is the part of the universe that has the ability to do work Chemistry is the study of matter The properties of different types of matter The way matter behaves when influenced by other matter and/or energy
Physical Properties are the characteristics of matter that can be changed without changing its composition. Characteristics that are directly observable Examples: odor, color, volume, state of matter, density, boiling point and melting point.
Extensive property – depend on the amount of matter present (length, mass, and volume). Intensive property – do not depend on the amount of matter present (melting point, boiling point, density).
Chemical Properties are the characteristics that determine how the composition of matter changes as a result of contact with other matter or the influence of energy
¬ The boiling point of ethyl alcohol is 78°C. Physical property – describes inherent characteristic of alcohol – boiling point Diamond is very hard. Physical property – describes inherent characteristic of diamond – hardness ® Sugar ferments to form ethyl alcohol. Chemical property – describes behavior of sugar – forming a new substance (ethyl alcohol) ® Digesting your breakfast or lunch - Chemical property – describes behavior of food – forming a new substance (depends on what you ate)
Physical Changes are changes to matter that do not result in a change the fundamental components that make that substance State Changes – boiling, melting, condensing Chemical Changes involve a change in the fundamental components of the substance Produce a new substance Chemical reaction Reactants Products Examples: burning, digesting, fermentation, decomposition.
1. Color change 2. Gas is formed (bubbles are produced). 3. Heat and light are produced. 4. A precipitate forms. A precipitate is a solid that is produced when two liquids are combined. Often a color change will occur as well.
¬ Iron is melted. Physical change – describes a state change, but the material is still iron Iron combines with oxygen to form rust.. Chemical change – describes how iron and oxygen react to make a new substance, rust ® Sugar ferments to form ethyl alcohol. Chemical change – describes how sugar forms a new substance (ethyl alcohol) ® A hot dog is cooked.
Substances which can not be broken down into simpler substances by chemical reactions are called elements Most substances are chemical combinations of elements. These are called compounds. Compounds are made of elements Compounds can be broken down into elements Properties of the compound are not related to the properties of the individual elements that in it. Same chemical composition at all times
Homogeneous = uniform throughout, appears to be one thing pure substances solutions (homogeneous mixtures) Heterogeneous = non-uniform, contains regions with different properties than other regions or phases Phase - any part of a system with uniform composition and properties.
Pure Substances All samples have the same physical and chemical properties Constant Composition all samples have the same composition Homogeneous Separate into components based on chemical properties
Mixtures Different samples may show different properties Variable composition Homogeneous or Heterogeneous Separate into components based on physical properties All mixtures are made of pure substances
¬ Gasoline a homogenous mixture A stream with gravel on the bottom a heterogeneous mixture ® Copper metal A pure substance (all elements are pure substances)
Separate mixtures based on different physical properties of the components Physical change Different Physical Property Separation Technique Boiling Point Distillation State of Matter (solid/liquid/gas)Filtration Adherence to a SurfaceChromatography VolatilityEvaporation
Distillation – liquid is boiled to produce a vapor that is then condensed again to a liquid. Filtration – pouring a mixture through a filter that will allow the smaller part of the mixture to flow through while collecting the larger particles. Chromatography – separation of a mixture into colors.
Magnets – if one component of the mixture is magnetic but another is not, the magnetic substance can easily be separated. Decanting – pouring the liquid off the top of the mixture while leaving the solid at the bottom undisturbed.
Capacity to do work chemical, mechanical, thermal, electrical, radiant, sound, nuclear Energy may affect matter e.g. raise its temperature, eventually causing a state change All physical changes and chemical changes involve energy changes
Heat - flow of energy due to a temperature difference 1. Exothermic = A process that results in the evolution of heat. Gas Liquid Solid are changes of state that are all exothermic processes Heat is exiting the system and going into the surroundings. It feels warm or hot to the touch.
2. Endothermic = A process that absorbs energy. Solid Liquid Gas are changes of state that are all endothermic processes. Heat is being put into the system from the surroundings. It feels cool or cold to the touch.
One calorie (cal) is the amount of energy needed to raise the temperature of one gram of water by 1°C. kcal = energy needed to raise the temperature of 1000 g of water 1°C joule (J) 4.184 J = 1 cal, 4.184 kJ = 1 kcal In nutrition, calories are capitalized 1 Cal = 1 kcal
How many kilojoules are there in 4.80 x 10 3 calories of energy?
The amount the temperature of an object increases depends on the amount of heat added (q). If you double the added heat energy the temperature will increase twice as much. The amount the temperature of an object increases depends on its mass If you double the mass it will take twice as much heat energy to raise the temperature the same amount.
Specific Heat (Cp) is the amount of energy required to raise the temperature of one gram of a substance by one Celsius degree Amount of Heat = Mass x Temperature Change x Specific Heat q = m TCp T = final temp. - initial temp.
What is the final temperature of aluminum (Cp = 0.90 J/g o C) that absorbs 425 J of energy when a 10.0 gram sample of aluminum is initially at 25 o C?
Calorimetry – an accurate and precise measurement of heat change for chemical and physical processes. If any reaction heat gained by the system or the surroundings equals heat lost by the system or the surroundings. q lost = - q gained
A 19.6-gram sample of a metal was heated to 61.7 o C. When the metal was placed into 26.7 grams of water in a calorimeter, the temperature of the water increased from 25.0 o C to 30.0 o C. What is the specific heat of the metal assuming that all of the heat lost by the metal was gained by the water?
A 50.0 gram sample of water at 100. o C was placed in an insulated cup. Then a sample of iron metal (Cp = 0.449 J/g o C) at 25.0 o C was added to the water. The temperature of the water dropped to 96.7 o C. What is the mass of the iron assuming that all of the heat lost by the iron was gained by the water?