Chemical Processes Part 1: Intro and Chemistry Basics

Chemical Processes Part 1: Intro and Chemistry Basics

How are chemistry and chemical engineering different? Chemists Small batches Determine reactions to make new compounds in test tubes Prepare and conduct laboratory procedures Chemical engineers Continuous, large quantities Design processes to manufacture compounds quickly, safely, and efficiently Study chemistry and engineering Typically more likely to pursue study beyond bachelors degree Typically have higher salaries All images are in the public domain. Photo at right shows a red pepper spice processing plant. 2

Products made by chemical engineers All images are in the public domain. 3

Types of chemical processes 4

How are chemicals produced? Reactions - Create new molecules out of two or more constituent components. Example: hydrogen from water Separations - Isolate a substance that is contained in a mixture of other ingredients. Example: gasoline from crude oil We are going to focus on two separation processes: distillation and chromatography. All images are in the public domain. 5

Separations How can you separate things? What material properties can you take advantage of to sort things automatically (not manually)? Examples: Sorting coins Sorting recycling Fresh water from salt water Properties: Size Magnetic or not Float or not (Density) Dissolve or not (Solubility) Melt or not (Melting temperature) Vaporize or not (Boiling temperature) https://www.pinterest.com/pin/522347256776220872 4/12/18 6

Distillation Distillation is a type of separation process that is useful in separating components of a liquid mixture that have different volatilities (tendency to evaporate). You will use distillation to separate ethanol and water. All images are in the public domain. 7

Distillation of crude oil One important example of distillation is the processing of crude oil into its components Videos: Fractional distillation of crude oil (4:05): https://www.youtube.com/watch?v=pymwuz7tc3a Use of crude oil fractions (4:05): https://www.youtube.com/watch?v=jzdvsqzokuk Inside a refinery (13:49): https://www.youtube.com/watch?v=9py8-xy9mko All images are in the public domain. 8

Chromatography Chromatography is a process in which different chemical substances are separated by making use of their different flow rates while being transported by a flowing solvent. You will use chromatography to separate dyes in marker ink. The solvents will be water and 2-propanol. All images are in the public domain. 1 solvent 2 paper 3 ink mixture 4 individual inks 5 solvent front 6 starting positions 9

Mass and moles 10

Stretch Quiz Hydrogen can be a great way to store and transport energy for transportation, heating, power generation, and more. Consider the plant below that splits water (H 2 O) into hydrogen (H 2 ) and oxygen (O 2 ). What mass of water is needed to produce 10.0 kilograms of hydrogen? Solution: 89.2 kilograms water You will learn how to do this calculation during this unit.?? kilograms of water (H 2 O) 2H 2 O 2H 2 + O 2 oxygen 10.0 kilograms of hydrogen (H 2 ) All images are in the public domain. 11

https://sciencenotes.org/periodic-table-for-kids-118-elements/ 4/12/18 Chemical element weights The periodic table provides element masses in units of grams per mole 12

Moles The periodic table provides element masses in units of grams per mole What is a mole? 12 of something is called a dozen. 6.022 x 10 23 of something is called a mole. (nearly a trillion trillion!) A dozen eggs has 720 grams mass... repeated a trillion trillion times https://sciencenotes.org/periodic-table-for-kids-118-elements/ 4/12/18 A mole of carbon atoms has 12 grams mass 13

Quiz What is the mass of one mole of water molecules? Each water molecule is made of 2 hydrogen atoms and 1 oxygen atom (H 2 O) Solution: 2 moles of hydrogen have 2*1.01 = 2.02 grams mass 1 mole of oxygen has 16.00 grams mass Together they have 18.02 grams mass... https://sciencenotes.org/periodic-table-for-kids-118-elements/ 4/12/18 14

Quiz How much does one mole of trinitrotoluene (TNT) molecules weigh? The chemical formula for TNT is C 7 H 5 N 3 O 6 Solution: 7 moles of Carbon: 7 mol * 12.01 g/mol = 84.07 g 5 moles of Hydrogen: 5 mol * 1.01 g/mol = 5.05 g 3 moles of Nitrogen: 3 mol * 14.01 g/mol = 42.03 g 6 moles of Oxygen: 6 mol * 16.00 g/mol = 96.00 g All together, the mass of one mole of TNT molecules is 227.15 g https://sciencenotes.org/periodic-table-for-kids-118-elements/ 4/12/18 15

Molar mass In the previous examples you calculated the following: Mass of 1 mole of water molecules = 18.02 grams Mass of 1 mole of TNT molecules = 227.15 grams We define the molar mass of a substance as the mass per amount of substance. The units are grams per mole. The molar mass of water is 18.02 grams. The molar mass of TNT is 227.15 grams. The molar mass of an element is the atomic mass from the periodic table. Molar mass of hydrogen (H): 1.01 g/mol Molar mass of Oxygen (O): 16.00 g/mol Molar mass of water (H 2 O): 18.02 g/mol 16

Quiz How many moles are in 25 grams of table salt (NaCl)? Solution: Molar mass: 22.99 g/mol (Na) + 35.45 g/mol (Cl) = 58.44 g/mol Number of moles: mol 25 g = 0. 43 mol 58.44 g https://sciencenotes.org/periodic-table-for-kids-118-elements/ 4/12/18 17

Mole fraction and mass fraction 18

Mole fraction and mass fraction Each molecule symbol below represents one mole with molar masses superposed Plant input 2H 2 O 2H 2 + O 2 18 18 2 2 32 Plant output The hydrogen molecules are more numerous, but they are less massive. Mass fraction Mole fraction mass fraction of X = mole fraction of X = mass of X mass of mixture moles ofx moles of mixture https://commons.wikimedia.org/wiki/file:electrolysis_of_water.png 4/12/18 19

Quiz The plant below produces 10.0 kg of hydrogen (H 2 ). How many moles of hydrogen does it produce? 1000 g 10.0 kg 1 kg 1 mol = 4950.5 mols 2.02 g How many moles of water (H 2 O) are needed to produce that many moles of hydrogen? Every 2 moles of water becomes 2 moles of H 2. So, we would need 4950.5 moles of water to produce 4950.5 moles of H 2. (2H 2 O 2H 2 + O 2 ) 89.2 kilograms of water (H 2 O) 2H 2 O 2H 2 + O 2 79.2 kilograms of oxygen (O 2 ) 10.0 kilograms of hydrogen (H 2 ) 20

Quiz What fraction of the total plant output (see below) is hydrogen? 11.2% 12.6% 66.7% 88.9% Solution: 11.2% by mass and 66.7% by mole 89.2 kilograms of water (H 2 O) 2H 2 O 2H 2 + O 2 79.2 kilograms of oxygen (O 2 ) 10.0 kilograms of hydrogen (H 2 ) 21

Conservation laws 22

Mass conservation In all chemical processes, mass is conserved (not created or destroyed). Mass may move from one place to another (like in distillation), but the total mass remains the same. Note that some mass may leave your experiment and move elsewhere, but it won t be destroyed! Reactions may change the total number of molecules, but the number of each atom remains the same. Plant input 2H 2 O 2H 2 + O 2 18 18 2 2 32 Plant output All images are in the public domain. 23

Energy conservation In all chemical processes, energy is conserved (not created or destroyed). Energy can move and change forms (kinetic, potential, thermal, electrical, etc), but the total energy in the universe (or an isolated system) remains constant. Your third lab for this unit will measure the efficiency of converting electrical energy into thermal energy by heating water on a hot plate. Engineering challenge: In an exothermic (heat-producing) reaction, the energy produced is proportional to the container volume, but the cooling is proportional to the container surface area. What happens when you scale-up and increase the container size? All images are in the public domain. 24