Class I Notes
Class I Notes CHEM 1311
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This 6 page Class Notes was uploaded by carolyn martinez on Saturday September 24, 2016. The Class Notes belongs to CHEM 1311 at University of Texas at Brownsville and Texas Southmost College taught by Vanessa Garcia in Fall 2016. Since its upload, it has received 22 views. For similar materials see General Chemistry I in Chemistry at University of Texas at Brownsville and Texas Southmost College.
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Date Created: 09/24/16
Chemistry Week I Notes Chemistry is the study of material and the changes it goes through Matter contains mass and space Molecules: Contains two or more atoms Ø Minor altercations can create different substances ???????? CO ▯ States of Matter Ø Gas – no stable volume or shape, maintains its shape and volume within the container. Ø Liquid- definite volume, no shape. Ø Solid- specific shape and volume ALL SUBSTANCES ARE EITHER COMPOUNDS OR ELEMENTS Ø Elements consist of one atom = cannot be broken down Ø Compounds consist of either two or more atoms = can be broken down Ø Mixtures can consist of two or more substance • Element + Element • Compound + Compound • Compound + Element Ø Mixtures can be: Homogeneous- dissolving sugar into water Heterogeneous- mixing sand with iron fillings Ø Quantitative properties can be expressed with using numbers Example: The turtle weighs 1 Kilogram (kg). Ø Qualitative properties does not need to be expressed using numbers Example: The turtle is brown Ø Physical Properties: can be seen without chaning the chemical composition. Example: color, melting point, boiling point. Ø Physical changes: changing the physical appearnce of a substance Example: solid à liquid, evaporation of water, freezing of water. Ø Chemical Properties is how a substance may react to create other substances. Example: Flammability, reactivity, oxidation, etc. Ø Chemical changes also known as a chemical reaction is when a substance can be changed into a different substance chemically. Ø Intensive properties can be described without the use of the amount of substance. Example: Temperature, and density. Ø Extensive properties: need amount of substance to determine. Example: Mass, volume, etc. Ø Scientific Method: units to record measuremen t. Ø SI Units: base for where all other units derive from. Mass and weight Ø Mass is measuring how much matter is in an object Ø Weight is measuring the force applied from an object because of gravity Weight can vary from place to place but mass does n’t Ø Temperature is how heat flows from an object with a higher temperature attracts to another object with lower temperature. C° - Celsius F°- Fahrenheit K°- Kelvin HOW TO CONVERT: • K = °C + 273.15 ▯ • °C = ▯(°F – 32) • °F = (°C) + 32 ▯ Volume: contains the measurements of: 3 • cubic centimeter (cm ) • milliliter (mL) • liter (L) 3 • Solids – cm • Liquids – mL • Gases – L Density: how much mass is in a unit of volume. FORMULAS: Know that density is room dependent on temperature at ( 25°C) room temperature unless told anoth▯▯▯▯empe▯ature. • Density = = ▯▯▯▯▯▯▯ ▯ • Solids = ▯ ▯▯▯ • Liquids = ▯▯ ▯ • Gases = ▯ Exact and Inexact numbers: Exact: known values Example: 12 eggs in a dozen, 24 crayons in a pack of 24 crayons. Inexact: uncertain values. Example: Human errors and equipment errors Significant figures: digits of a stately measure Example: 2.2 has two sig figs 2.2405 has five sig figs Basically, the more number of significant figures, THE BETTER. ± ß this sign just express the magnitude of the number. • Example: 2.2405 ± 0.0001 g (5 being the uncertain digit) Start counting the figures by going from left to right with the FIRST non - zero digit. SOME ZEROS ARE NOT SIGIFICANT DUE TO THEIR LOCATION: 1. Any non-zero is SIGNIFICANT 2. Zeros between on-zero numbers COUNT. 3. Zeros in the beginning DO NOT COUNT EXAMPLE: • 0.02 g – one significant figure • 0.0026 g – two significant figures 4. Zeros at the end are significant if it previously has a decimal point Example: 0.200 three sig figs; 3.0 two sig figs 10 ± ▯▯▯▯▯▯ can represent the number of zeroes Example: 4 1.03 X 10 4 – three significant figures 1.030 X 10 g – four significant figures REMEMBER WHEN YOU ADD, SUBTRACT, DIVIDE OR MULTIPLY CHOOSE USE YOUR NUMBER WITH THE SMALLEST AMOUNT OF SIGNIFCANT FIGURES TO MATCH YOUR ANSWER Example: • 20.42 + 1.322 + 83.1 = 104.842 ≈ 104.8 • 6.221 x 5.2 = 32.3492 ≈ 32 Precision: receiving the same/similar measurement over different trials. Accuracy: How similar a measurement us close to the original or true value. (8.50 in.)(▯.▯▯ ▯▯ ) = 21.59 cm ▯ ▯▯ ▯.▯▯▯▯ ▯▯ ▯▯▯▯ ▯ (0.0550 mi)( ▯ ▯▯ )( ▯ ▯▯ ) = 88.5 m
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