Warm-Up (9/26) (1.) List and describe in detail the 5 components that make up a good science lab...
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Transcript of Warm-Up (9/26) (1.) List and describe in detail the 5 components that make up a good science lab...
Warm-Up (9/26)(1.) List and describe in detail the 5 components
that make up a good science lab report.(2.) Write the following in scientific notation:
a.) 0.00076 gb.) 345,900,000 Lc.) 82.1 m
(3.) Convert the following measurements:a.) 23 m cmb.) 9.48 mL dLc.) 7.6 Mg pg
Answers to Warm-Up (9/26)
(1.) Introduction, Materials, Procedures, Data Table, Conclusion(2.) a.) 7.6 x 10-4 g
b.) 3.459 x 108 Lc.) 8.21 x 101 m
(3.) a.) 2.3 x 103 cmb.) 9.48 x 10-2dLc.) 7.6 x 1018 pg
Extensive and IntensiveExtensive – depends on the amount of matter in a sample (mass or volume)
Intensive – depends on the type of matter in a sample (hardness/softness)
Identifying Substances
Physical Property – a quality or condition of a substance that can be observed or measured without changing the substance’s composition
Look at the 3 objects I have on the front demo table…Every sample of a given substance has identical intensive properties because every sample has the same composition.
Types of Mixtures(1.) Homogeneous – a mixture in which the composition IS uniform throughout (oil, vinegar)
(2.) Heterogeneous – a mixture in which the composition IS NOT uniform throughout (chicken soup, salad, oil & vinegar)
Separating Mixtures(Observe the heterogeneous mixture of Styrofoam, pennies, and water)
You can use a variety of methods to separate mixtures depending on the substances and their physical properties.
• Filtration – process that separates a solid from a liquid in a heterogeneous mixture (cooked pasta in a colander, coffee)
• Distillation – a process involving liquid being boiled to produce a vapor, which is then condensed back to a liquid
Substances vs. Mixtures
Substance – composition of a material is fixed (Elements and Compounds)
Mixture – composition of a material varies (Homogeneous and Heterogeneous Mixtures)
Elements and Compounds Element –
simplest form of matter that has a unique set of properties
Compound – substance that contains two or more elements chemically combined in a fixed proportion
Symbols and Formulas Chemists use chemical symbols to
represent elements, and chemical formulas to represent compounds
Each element is represented by a 1- or 2-letter chemical symbol
The 1st letter is always CAPITALIZED, while the 2nd letter (if used) is lowercase.
(Example: H, O, C, Cl, He, Na)
Physical Changes During a physical change, properties of
a material change, but the composition of the material does not.
Physical Changes include…
BOILING
MELTING
FREEZING
CONDENSING
BREAKING
CUTTING
CRUSHING
Reactant versus Product
Reactants - Substance present at the beginning of the reaction (left side)
Products - Substance present at the end of the reaction (right side)
Reactant Product
(1.) Transfer of energy (heat)
(2.) Change in color
(3.) Produces a gas (bubbles)
(4.) Forms a precipitate (solid that forms and settles out of a liquid mixture)
Recognizing Chemical Changes…
Conservation of Mass During any chemical reaction, the
mass of the products is always equal to the mass of the reactants
Example: 10 grams of ice melts into 10 grams of water
Law of Conservation of Mass – mass is conserved in any physical change or chemical reaction (mass is neither created nor destroyed)