Chemistry SM-1131Week 3 Lesson 1 Dr. Jesse Reich Assistant Professor of Chemistry Massachusetts Maritime Academy Fall 2008
Class Today • Wiki • Sea Fever • Working with Density • Matter- solid/liquid/gas, pure v. mixture, physical v. chemical, physical changes v. chemical changes • Separating Matter • Wednesday = Energy and Temperature, maybe some problems
Sea Fever I must down to the seas again, to the lonely sea and the sky,And all I ask is a tall ship and a star to steer her by,And the wheel's kick and the wind's song and the white sail's shaking,And a grey mist on the sea's face, and a grey dawn breaking.I must down to the seas again, for the call of the running tideIs a wild call and a clear call that may not be denied;And all I ask is a windy day with the white clouds flying,And the flung spray and the blown spume, and the sea-gulls crying.I must down to the seas again, to the vagrant gypsy life,To the gull's way and the whale's way where the wind's like a whetted knife;And all I ask is a merry yarn from a laughing fellow-roverAnd quiet sleep and a sweet dream when the long trick's over.By John Masefield (1878-1967).(English Poet Laureate, 1930-1967.)
Also Join Wikispaces • Go to www.wikispaces.com • Click on get an account • Fill out the form, but don’t get a wiki of your own. • Check your email • Verify your account • Go to reich-chemistry.wikispaces.com and click join space. • Confirm with me that it all worked
Start a Wiki Example • OK, we’re going to work on Wikis This only works if you have signed in • 1 open up the web page • 2 click on the atomic history wiki-timeline link • 3 click on your class • 4 click edit this page • Type in: Fall.2008.MMA.lastname1.lastname2.timeline
Making a link • Highlight the text you just wrote • Click on the icon in the top bar that has a chain in it. • Click ok when the pop up comes • Click Save • If you do something bad like erase someone else’s don’t save what you did. Just hit cancel.
Once you make a link • Click on your link • Hit edit this page • Type in John Dalton looks like D. Reich • Hit Save • Notice how all the computers in the world can now see that John Dalton looks like D. Reich • You’re going to make your wiki like this. • Be sure to save often!
Density • Density = Mass volume d = m v
Let’s calculate density • I have a ball of metal that takes up 3ml and weighs 12.6g. What is it’s density? d = m v d= 12.6g= 4.2 g/ml, but 3ml only has 1 sig fig 3ml OK so, finally 4 g/ml would be the answer!
Let’s use density • In lab I draw out 15ml of a liquid that has 1.67 g/ml. How much mass does it have? • (copy the given, and use the density) 15ml * 1.67 g = 25.05g ml
Let’s use density… Again • A recipe calls for 200.ml of ethanol, which has a density of 0.789g/ml. How many grams did we add? 200. ml ethanol* 0.789 g ethanol= 157.8 ethanol ml 158g => 1.58g e2
Matter • Definitions: vocab. words to memorize • Matter: Anything that has mass and takes up space. • Elements: The most basic different types of matter. You can’t break it down into other substances. • Atoms: The smallest distinguishable unit of an element. • Molecules: 2+ more atoms bonded together.
Phases of matter: Solid • Solid: atoms and/or molecules packed very close together. Hard, dense, fixed location. • Crystalline solid v. amorphous: Crys. Atoms and molecules are in geometric patterns that repeat. Amorphous solids they are in random order and can be somewhat flexible like glass or rubber.
Phases of Matter: Liquid • Atoms and molecules are more spaced out and now can move. The material can be slightly compressed into a smaller space. • They don’t have a defined shape, but take the shape of their container.
Phases of Matter: Gas • Atoms and molecules are far apart • Atoms and molecules move freely • The gas can be compressed significantly • Assumes the shape of the container
Elements, Compounds, Mixtures • If there is only 1 atom type or molecule type in a given space we call it a pure substance • If there are 2 or more atom types or molecules in a given space we call it a mixture.
Elements • Can’t be broken down into simpler or other substances. • You can do whatever you want to pure copper. You can’t find a simpler version of copper. • You can do whatever you want to graphite. You can’t find a simpler form of graphite.
Compounds • Compounds are substances composed of 2 or more elements in fixed and definite proportions. • You can mess with compounds to turn them back into elements. • You can have a pure compound, where in a contained space it’s only made up of that one compound ie pure water, pure CO2, etc.
Mixture • When you combine at least two pure elements, at least two pure compounds, or at least 1 pure element and 1 pure compound into the same space.
Homogeneous Mixture • A uniform mixture where you can’t otherwise tell that there are multiple phases. If it’s gases it’s homogeneous, if it’s liquids and you can see through it it’s homogeneous, if it’s solids you have to look at it. Steel is a mixture of iron and carbon, but you wouldn’t know. A box of copper and steel nuts you can tell apart. • Tea is a homogeneous mixture. Milk is not.
Heterogeneous Mixture • If you can clearly tell that there are more than one thing in a container it’s heterogeneous • If there is a liquid that you can’t see through it’s heterogeneous • If you can tell there is an easy way to separate things then it’s a heterogeneous mixture.
Homework • Get your wiki up. Put in a couple of scientists • Get your homework in by Monday