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Matter. Ch. 16. How do Scientists Classify Matter?. Matter can be divided into two categories: mixtures and substances . Mixtures contain more than one kind of matter. Example: Cola can be separated into carbonated water, corn syrup, caffeine, etc .
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Matter Ch. 16
How do Scientists Classify Matter? • Matter can be divided into two categories: mixturesand substances. • Mixtures contain more than one kind of matter. • Example: Cola can be separated into carbonated water, corn syrup, caffeine, etc. • Substances cannot be separated into different kinds of matter by physical means. • Example: water, gold, silver, etc.
Mixtures • Mixtures can fit into two categories: • Homogeneous: the same throughout. • Example: An unopened can of juice is the same at the top and bottom of the can. • Solutions: heterogeneous mixtures in which one thing is dissolved into something else. • Examples: salt water, carbonated beverages. • Heterogeneous: different samples are not necessarily made up of exactly the same proportions of matter. • Example: Chicken noodle soup. One spoonful might contain more liquid, noodles, or vegetables than another spoonful. • Suspensions: heterogeneous mixtures in which particles are floating and will eventually settle out. • Examples: muddy water • Colloids: heterogeneous mixtures in which particles are floating and won’t settle out. • Examples: milk, smoke.
Separating Mixtures • Mixtures can be separated by physical means. • ALL mixtures (homogeneous or heterogeneous) can be separated by means of: • Filtering • Heating • Sorting • Cooling • The separation process DOES NOT change the characteristics of each component. • If I separate the noodles, veggies, chicken, and broth out of my soup, they are still noodles, veggies, chicken, and broth.
Paper Chromatography • Technique for separating and identifying mixtures that are or can be colored. • Also called Thin layer chromatography. • It is done by: • Placing a spot of the mixture near the bottom of a strip of chromatography paper. • Hanging the paper into a solution (water) so that the bottom 2 centimeters of the paper are in the solution. • Waiting and watching. The solution will move up the paper, separating the mixture as it goes.
Substances • Can not be separated into different kinds of matter by physical means. • Elements: Substances that contain only one kind of matter are called. • Example: gold, copper, iron, etc. • Compounds: Substances that are made of two or more elements that cannot be separated by physical means are called. • Example: table salt – contains both sodium and chlorine. Rust (iron oxide) also cannot be separated.
Measuring the Mass of Matter • Mass: the amount of matter in an object. • DIFFERENT from WEIGHT: your weight is affected by gravity. • Your mass is not – it will stay the same everywhere in the universe. • Measuring devices: • Scales: measures the force gravity exerts on the object. • Balance: measures mass of an object by comparing it with a known mass.
Measuring the Volume of matter • Volume: measures the amount of space that an object takes up. • When measuring a LIQUID: • Use things like measuring cups, graduated cylinders, or beakers. • Remember: • When reading the volume, read at eye level and at the bottom of the meniscus!
To find the volume of a solid, you can: • Use a mathematical formula: • Use Displacement: if it’s a weird shape, submerge it in water and measure the amount of water displaced. • The volume of the object is the same as the amount of water displaced. • To find the volume, subtract the volume of the water before the object was submerged from the volume after it was submerged.
Measuring VERY large masses How could I measure the mass of a tennis court? • Indirect Measurement: measurement made when it is not possible to use a device to measure directly. • Remove a piece of asphalt from the court. • Use the displacement method to measure the volume of the tennis court. • It’s about 1687cm3. • Use a balance to measure the mass of the asphalt. • It’s about 1.94 kg. • Measure the volume of the court: • Volume of a rectangle = L x W x H. • Volume = 36.51m x 18.29m x 0.075m • Volume = 50.08 m3.
NOW WE SET UP A PROPORTION. • MASS OF CHUNK = MASS OF COURT VOLUME OF CHUNK VOLUME OF COURT • PLUG NUMBERS INTO THE FORMULA THAT YOU KNOW. • YOU MUST CHANGE 1687 cm3 TO m3 SO UNITS WILL MATCH. 1.94kg = ( X ) .001687m3 50.08m3 • NOW CROSS MULTIPLY (1.94kg)(50.08m3) = (.001687m3) (X kg) • GET X ON ONE SIDE OF THE = SIGN BY DIVIDING EACH SIDE BY .001687 (1.94kg)(50.08m3) = (.001687m3) (X kg) .001687m3 .001687m3 • MULTIPLY & DIVIDE TO SOLVE FOR kg • 57,590.5kg IS THE MASS OF THE TENNIS COURT
MEASURING VERY SMALL MASSES How can I measure the mass of a piece of paper? • You can measure the mass of something small? • MEASURE OBJECT WHOSE MASS DOES NOT REGISTER ON THE BALANCE (0.0g) BY MEASURING MANY OF THE OBJECTS AND DIVIDING BY HOW MANY OBJECTS THERE ARE. • EX. 50 PIECE OF PAPER WEIGH .10 lb. • DIVIDE .10 lb BY 50 TO KNOW MASS OF 1 PIECE OF PAPER
Breaking Down Matter • Matter is made up of different components: • Molecules: the smallest part of a compound that retains the properties of that compound. • Contains AT LEAST two atoms. • Atoms: the smallest parts of elements.
Atoms are ALWAYS in motion. • Since atoms make up molecules, so are they. • Movement is affected by temperature: • At High Temperatures they move fast with lots of energy. • When moving faster, they bump into each other more. • At Low Temperatures they move slow with little energy. • Is there a temperature where atoms will stop moving? • Yes: Absolute Zero. • It is 0°K (kelvin) or -459°F.
STATES OF MATTER • Matter exists in four states: • Solids: the molecules vibrate, but they can’t move around and switch places. • Solids retain their shape and size. • Liquids: are able to move over and around each other. • Liquids have a definite volume, but no shape. • They take the shape of whatever container they are in.
Gas: molecules are able to move very quickly throughout a container. • Have no definite shape or size. • Spread evenly throughout the space they’re in. • Plasma: The most common state of matter. • Acts like a gas, but can be influenced by a magnetic field. • Rare on Earth. • Occurs at extremely high temperatures. • These temperatures cause atoms to break apart. • Found in stars. • Each phase changes with temperature:
CHANGES OF STATE • Remember: atoms, and thus molecules, are always in motion. • They also vibrate. • All elements exist as a solid, liquid, or gas. • When a substance changes state, ONLY the movement of the molecules change. • The number of them remains the same.
The state of matter that a substance is in in influenced by its temperature. • Temperature is a measure of the average energy of the molecules and their average speed. • The higher the temperature, the more energy they have and the faster they move. • As their energy and speed increases, their state changes.
Each substance has a specific temperature and pressure at which it will undergo a change of state: • Melting Point: the temperature at which a substance changes from a liquid to a solid. • Water = 0°C (32°F) • Iron = 1538°C (2800°F) • Boiling Point: the temperature at which a substance goes from a liquid to a gas. • Water = 100°C (212°F) • Iron = 2861°C (5182°F)
The Process of Changing State • As substance change state, certain processes are involved. • Evaporation: occurs when fast moving molecules in a liquid escape to become a gas. • As high energy molecules escape as gas, heat is taken from the area immediately surrounding the substance. • The result is that anything touching the substance feels colder. • Ex. When you sweat – the sweat evaporates from your skin, cooling you down.
Condensation: when a substance changes from a gas to a liquid. • Occurs as the temperature decreases. • When this happens, energy is lost into the area surrounding the object, thus the area feels warmer. • Ex. Water Vapor (gas) in the atmosphere cools and forms rain drops (liquid). • Freezing: when a substance changes from a liquid to a solid. • Melting: when a substance changes from a solid to a liquid. • Sublimation: when a substance goes directly from a solid to a gas when heated. • The opposite of this is called deposition.