NU LIPA Course Material 1: Introduction to Chemistry and Measurements PDF

Introduction to Chemistry and Measurements Learning Outcomes Understand and explain the definition, history, and main branches of chemistry. Practice the use of metric system units, significant figures, and scientific notation in chemical measurements. Utilize conversion factors and dimension...

Introduction to Chemistry and Measurements Learning Outcomes Understand and explain the definition, history, and main branches of chemistry. Practice the use of metric system units, significant figures, and scientific notation in chemical measurements. Utilize conversion factors and dimensional analysis to solve measurement problems. Calculate density and use it as a conversion factor. Convert temperatures between Celsius, Kelvin, and Fahrenheit scales. Differentiate between accuracy and precision and apply these concepts to improve the reliability of measurements in scientific experiments. Topic Outline Introduction to Chemistry Definition, History, Branches Measurements in Chemistry Measurement Dimensional Analysis Systems Density Metric System Units Temperature Scales Significant Figures Accuracy and Scientific Notation Precision Conversion Factors Topic Outline Introduction to Chemistry Definition, History, Branches Measurements in Chemistry Measurement Dimensional Analysis Systems Density Metric System Units Temperature Scales Significant Figures Accuracy and Scientific Notation Precision Conversion Factors What is Chemistry? the branch of science that deals with the identification of the substances of which matter is composed the investigation of their properties and the ways in which they interact, combine, and change the use of these processes to form new substances Brief History of Chemistry Origins of the term Chemistry ✓By 1000 BC ancient civilizations were came from the following: applying different branches of Arab Latinized "Keme" chemistry. meaning “value” ✓The first chemical reaction that was used in a controlled manner was fire. Egyptian “Khemia" meaning ✓Purifications of metals was first "transmutation of earth“ recognized as early as 2600 BC by Egyptians during purification of Gold. ✓Discovery of alloys marked the start of Greek "Khymeia" meaning Bronze age (3300 BC) "art of alloying metal“ and "Khumeia" meaning "putting ✓Advancement in alchemy and together" metallurgy in Ancient India Brief History of Chemistry Branches of Chemistry Branches of Chemistry The study of the structure, properties, composition, Organic Chemistry reactions, and preparation of carbon-containing compounds Most organic compounds contain carbon and hydrogen, but they may also include any number of other elements (e.g., nitrogen, oxygen, halogens, phosphorus, silicon, sulfur) Branches of Chemistry The study of the structure, Inorganic Chemistry properties and reactions of noncarbon chemical compounds or those that do not contain carbon- hydrogen bonds substances which do not have carbon-hydrogen bonding are metals, salts, chemical substances Branches of Chemistry Physical Chemistry The study of the behavior of matter at an atomic or molecular level It also involves the study of the properties of substances at different scales, from the macroscopic scale, which includes particles that are visible to the naked eye, to the subatomic scale. Branches of Chemistry Involves the separation, Analytical Chemistry identification (qualitative analysis), and the quantification of matter (quantitative analysis). It involves the use of classical methods along with modern methods involving the use of scientific instruments. Branches of Chemistry The application of Biochemistry chemistry to the study of biological processes at the cellular and molecular level. A laboratory-based science combining biology and chemistry Topic Outline Introduction to Chemistry Definition, History, Branches Measurements in Chemistry Measurement Dimensional Analysis Systems Density Metric System Units Temperature Scales Significant Figures Accuracy and Scientific Notation Precision Conversion Factors Measurement Measurement is the determination of the Measurement dimensions, capacity, Systems quantity, or extent of something. 1. English system of units The units of this system In chemical laboratories, include the inch, foot, pound, the most common types quart, and gallon. of measurements are 2. Metric system of units those of mass, volume, The units of this system length, time, temperature, include the gram, meter, and pressure, and liter. concentration. Measurement English System Base Unit also called British Property Unit Abbreviation Imperial System Length Foot ft Mile mi Yard yd a collection of measures for length, volume, Area Acre ac weight, area, etc. that Volume Pint pt have their roots in Quart qt hundreds of years of Gallon Gal history Weight Pound lb Ton ton Measurement Metric System Base Unit In the metric system, Property Unit Abbreviation there is one base unit Mass Kilogram kg for each type of Length Meter m measurement (length, Volume Liter L mass, volume, and so Time Second s on). Temperature Kelvin K Electric Current Ampere A SI System Amount of Mole mol substance Luminous Candela cd intensity Measurement Metric System The names of fractional parts of the base unit and multiples of the base unit are constructed by adding prefixes to the base unit. Topic Outline Introduction to Chemistry Definition, History, Branches Measurements in Chemistry Measurement Dimensional Analysis Systems Density Metric System Units Temperature Scales Significant Figures Accuracy and Scientific Notation Precision Conversion Factors Significant Figures The digits in a measurement that are known with certainty plus one digit that is estimated. 1. All non-zero numbers ARE significant. 33.2 has three significant figures 2. Zeros between two non-zero digits ARE significant 2051 has four significant figures 3. Leading zeros are NOT significant. 0.0032 also has TWO significant figures 4. Trailing zeros to the right of the decimal ARE significant. 92.00 has FOUR significant figures Significant Figures 5. Trailing zeros for a whole number that ends with a decimal point are significant. 540. has three significant figures 6. Trailing zeros for a whole number that do not end with decimal point are NOT significant. 540 has two significant figures 7. Exact numbers, and irrationally defined numbers pi (π) has an infinite number of significant figures 8. For any value written in scientific notation as A ×10^x, the number of significant figures is determined by applying the above rules only to the value of A 4.500 × 103 has four significant figures Sample Problem Identify the number of significant figures in the following numbers: 1. 0.00125 6. 27× 103 2. 2,000,000,000 7. 281 × 102 3. 796,000 8. 0.00179 4. 872 9. 0.0000763 5. 90 10. 367 × 103 Scientific Notation A way of writing numbers that are too large or too small to be conveniently written as a decimal. Scientific Notation Scientific Notation Scientific Notation Sample Problem Change the following numbers to scientific notation. 1. 0.00125 2. 2,000,000,000 3. 796,000 4. 872 5. 90 Topic Outline Introduction to Chemistry Definition, History, Branches Measurements in Chemistry Measurement Dimensional Analysis Systems Density Metric System Units Temperature Scales Significant Figures Accuracy and Scientific Notation Precision Conversion Factors Conversion Factor A ratio that specifies how one Weight unit of measurement is 16 ounces (oz) 1 pound (lb) related to another unit of 2000 pounds (lbs) 1 ton measurement. 2.2 pounds (lbs) 1kilogram (kg) Length Capacity 1 inch (in) 2.54 cm 3 teaspoons (tsp) 1 tablespoon (tbsp) 12 inches (in) 1 foot (ft) 16 tablespoon (tbsp) 1 cup (c) 3 feet (ft) 1 yard (yd) 8 ounces (oz) 1 cup (c) 5280 feet (ft) 1 mile (mi) 2 cup (c) 1 pint (pt) 1 km 3280 feet (ft) 2 pint (pt) 1 quart (qt) 4 quartz (qt) 1 gallon (gal) 3.785 liter (L) 1 gallon (gal) Dimensional Analysis general problem-solving method in which the units associated with numbers are used as a guide in setting up calculations. Step 1: Identify the known or given quantity (both numerical value and units) and the units of the new quantity to be determined. Step 2: Multiply the given quantity by one or more conversion factors in such a manner that the unwanted (original) units are canceled, leaving only the desired units. Step 3: Perform the mathematical operations indicated by the conversion factor setup. Dimensional Analysis Example: Convert 1516 g to kg. 1 𝑘𝑔 For grams to cancel out, grams in 1516 𝑔 × the conversion factor must be on 1000𝑔 the opposite side of the fraction Conversion factor 1516 × 1 Multiply every number on top of the fraction and divide by the 1000 bottom = 1.516 𝑘𝑔 Sample Problem Convert 7.5 km to mm. 1000𝑚 1000𝑚𝑚 7.5 𝑘𝑚 × × = 𝟕 𝟓𝟎𝟎 𝟎𝟎𝟎 𝒎𝒎 1 𝑘𝑚 1𝑚 Convert 10 pt to gal. 1 𝑞𝑢𝑎𝑟𝑡𝑧 1 𝑔𝑎𝑙 10 𝑝𝑖𝑛𝑡𝑠 × × = 𝟏. 𝟐𝟓 𝒈𝒂𝒍𝒍𝒐𝒏𝒔 2 𝑝𝑖𝑛𝑡𝑠 4 𝑞𝑢𝑎𝑟𝑡𝑧 Sample Problem Convert the following: 1. What is 0.0032 gallons in cL? 𝟑. 𝟕𝟖𝟓𝑳 𝟏𝟎𝟎𝒄𝑳 𝟎. 𝟎𝟎𝟑𝟐𝒈𝒂𝒍 𝒙 𝒙 = 𝟏. 𝟐𝟏𝟏𝟐 𝒄𝑳 𝟏𝒈𝒂𝒍 𝟏𝑳 2. Convert 3598 grams into pounds. 𝟏𝒌𝒈 𝟐. 𝟐𝒍𝒃𝒔 𝟑𝟓𝟗𝟖𝐠 𝒙 𝒙 = 𝟕. 𝟗𝟏𝟓𝟔𝒍𝒃𝒔 𝟏𝟎𝟎𝟎𝒈 𝟏𝒌𝒈 3. Convert 500 quartz into ounce. 𝟐 𝒑𝒕 𝟐𝒄 𝟖𝒐𝒛 𝟓𝟎𝟎𝒒𝒕 𝒙 𝒙 𝒙 = 𝟏𝟔, 𝟎𝟎𝟎 𝒐𝒛 𝟏𝒒𝒕 𝟏𝒑𝒕 𝟏𝒄 Topic Outline Introduction to Chemistry Definition, History, Branches Measurements in Chemistry Measurement Dimensional Analysis Systems Density Metric System Units Temperature Scales Significant Figures Accuracy and Scientific Notation Precision Conversion Factors Density the ratio of the mass of an object to the volume occupied by that object 𝑀𝑎𝑠𝑠 𝐷𝑒𝑛𝑠𝑖𝑡𝑦(𝜌) = 𝑉𝑜𝑙𝑢𝑚𝑒 Although any mass and volume units can be used, densities are generally expressed in grams per cubic centimeter (g/cm3) for solids, grams per milliliter (g/mL) for liquids, and grams per liter (g/L) for gases. Densities of Selected Substances Density as a Conversion Factor Problem: Blood plasma has a density of 1.027 g/mL at 25°C. What volume, in milliliters, does 125 g of plasma occupy? 1 𝑚𝐿 125 𝑔 1.027 𝑔 = 𝟏𝟐𝟏. 𝟕𝟏 𝒎𝑳 Sample Problem If your blood has a density of 1.05 g/mL at 25°C, how many grams of blood would you lose if you made a blood bank donation of 1.00 pint (473 mL) of blood? 1.05 𝑔 473 𝑚𝐿 × = 𝟒𝟗𝟔. 𝟔𝟓 𝒈 𝑚𝐿 Temperature Scales Heat is a form of energy. Temperature is an indicator of the tendency of heat energy to be transferred. Heat energy flows from objects of higher temperature to objects of lower temperature. Three different temperature scales are in common use: Celsius, Kelvin, and Fahrenheit. Conversion between Temperature Scales 𝐾 = °C + 273.15 °C = 𝐾 − 273.15 9 °F = (°C) + 32 5 5 °C = (°F − 32) 9 Sample Problem The body temperature of a person with a high fever is found to be 104°F. What is this temperature equivalent to on the Celsius scale and Kelvin scale? 5 °C = (104− 32) 𝐾 = 40 + 273.15 9 °C = 40 °C 𝐾 = 313.15 K Sample Problem The body temperature for a hypothermia victim is found to have dropped to 29.1° C. What is this temperature in degrees Fahrenheit? 9 °F = (29.1) + 32 5 °F = 84.38°F Topic Outline Introduction to Chemistry Definition, History, Branches Measurements in Chemistry Measurement Dimensional Analysis Systems Density Metric System Units Temperature Scales Significant Figures Accuracy and Scientific Notation Precision Conversion Factors  Accuracy and Precision ACCURACY PRECISION measure of measure of how close a how close a measurement series of is to the correct or measurements accepted are to one value of the another quantity being measured Standard deviation Mean Accuracy and Precision Determine the level of accuracy and precision.  NEXT TOPIC Atomic Structure and the Periodic Table