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Chem Chapter 1-2.3
Question | Answer |
---|---|
Chemistry? | the study of the composition of matter and the changes it undergoes |
5 ways to tell a chemical reaction occurred? | 1. color change 2. light 3. heat 4. gas released 5. precipitate produced |
Scientific Method? | a logical ,systematic approach to solving or developing an explanation for a scientific question |
What are the steps of the scientific method? | -make observation -propose hypotheses -test hypotheses -develop theory |
independent variable? | the variable that is purposefully changed in an experiment |
dependent variable? | the variable affected by the changed variable |
control? | the variable in an experiment kept the same |
What's the difference between a theory and a hypothesis? | a theory is a well tested, broad explanation and a hypothesis is a proposed answer to a question |
matter? | anything that has mass and takes up space |
mass? | how much matter is in an object |
volume? | how much space an object occupies |
extensive property? | depends on the amount of matter |
intensive property? | depends on the type of matter |
substance? give two types of substances. | matter that has a uniform and definite composition; elements and compounds |
physical property? | quality that can be observed without changing the identity |
chemical property? | property that in order to be observed, a chemical change must occur |
list three physical properties of tap water. | color: clear, Boiling point: 100C, state at room temp: liquid |
how do you distinguish between two liquids that look the same? | boiling point, by distillation |
how do you separate sand and table salt? | dissolve salt in water and filter sand through a strainer |
vapor? | the gaseous state of a substance that is liquid at room temp |
physical change? | when properties of a material change but the composition does not |
chemical change? | when a change occurs that changes the makeup of a substance |
mixture? | physical blend of 2+ compounds |
heterogeneous mixture? | a mixture that is not uniform throughout |
homogeneous mixture? | uniform composition |
solution? | homogeneous mixture |
phase? | used to describe any part of a sample with uniform composition and properties |
filtration? | physical separation based on solubility. use to separate a solid from a liquid. |
distillation? | physical separation based on boiling point. use to separate water from liquid |
chromatography? | physical separation based on dissolvability. mobile and stationary phases |
element? | simplest form of matter |
compound? | contains 2+ elements in a chemically combined fixed proportion |
how is periodic table organized? | by atomic number |
period on periodic table? | horizontal row |
group on periodic table? | vertical column |
order of metric unit prefixes? largest to smallest. | kilo, _unit_, centi, milli, micro, nano |
Convert 2.7m to millimeters. | 270mm |
scientific notation rules? | if the dot's in sight, count left to right. if the dot's not in sight, count right to left starting with the first significant figure. |
multiplication/division rules? | the value with the least number of significant figures in the starting problem is the most significant figures you can report in your answer |
addition/subtraction rules? | line up decimals and round to the first column value that is completely lined up |
accuracy vs precision? | accurate is in the targeted area, precise is together in the same area. |
density formula? | Density=Mass/Volume |
Percent Error formula? | Average|(Actual-Observed)/Actual| x 100 |