Welcome to Chemistry 116! Lab Safety and Proper Procedure Labs 1 & 2

How to print out notes Go to file, click on print, look for print what change from slides to handouts; then adjust how many you want per page. Also change color to pure black & white.

Introduction Today, we will look at some common chemistry lab equipment and its proper use. The equipment you will be using: Bunsen burner beakers graduated cylinders burettes Eudiometer tubes balance

The Bunsen Burner The air inlet valve controls the amount of air into the flame; the more air, the more orange the glow Always use the striker at a 45° angle For most labs, a 3’ flame is sufficient

The Hotplate/Stir plate Most hotplates double as stir plates. The Teflon coated metal “tablet” or stir, helps to evenly heat the solution. Always remember to UNPLUG hotplates when exiting the lab.

The Digital Balance The top loading balance in a general lab will be accurate to: 0.01 grams - centigram balance grams - milligram balance or grams is considered analytical.

The Beaker & the Graduated Cylinder The graduated cylinder allows you to deliver precise volumes of liquid. The beaker is useful for transferring solutions from one vessel to another.

The Burette & The Eudiometer Tube The burette is useful because you can deliver relatively precise amounts of liquid into a vessel.

Procedures Page Bunsen burner Demo: learn the proper use 2. Operate a hotplate/stir plate (DEMO) 3. Measuring length: measure the length of a test tube  0.1 cm 4. Using a top-loading digital balance measure the mass of one 100 beaker on both the centigram and the milligram balance 5. Omit analytical balance procedure, reading volume measurements using the meniscus, and determine accuracy in measuring liquid volumes

Density Density is the amount of mass per given volume: It is specific to every substance It is often referred to as specific gravity m is expressed in grams and v in milliliters ex: Water is 1g/mL

Lab# 2 pg35-37 Pg 35 Determine the density of various samples of water. –Obtain and determine the mass a empty 100mL. beaker. –Record the mass of the empty beaker. –Add 5mL. of water to the beaker and determine the mass. –Add 5mL. More of water and determine the mass. – Repeat process until a total of 25mL. of water has been added to the beaker.

Lab # 2 Continued Pg36 # 2 Determine the density by displacement. –Obtain a sphere, slide it into graduated cylinder to determine the volume of the sphere. –Calculate density # 3 Determine the density by direct measurement. – Obtain a cube and measure LxWxH to determine volume –Calculate density.

Melting & Boiling Points Melting point: where the solid and liquid phases co-exist at a fixed temperature Boiling point: the point where the liquid and vapor phases coexist; the boiling point for a liquid depends upon the temperature and pressure Water, the standard, has a melting point of 0°C and a boiling point of 100 °C (This is 32 °F and 212 °F respectively)

Solubility Solubility is the ability of a substance to dissolve in solution, making the substance soluble An insoluble substance will not dissolve. Like dissolves like: general rule of thumb that states that polar substances and nonpolar substance will not dissolve each other. Solute: that which is dissolved (NaCl) Solvent: that which dissolves the solute (H 2 O) Na 1+ NaCl H2OH2OH2OH2O Na 1+ Cl 1- Na 1+

Solubility(2) Salts like NaCl are ionic and polar in nature and will dissolve in water, another polar substance. –They will not dissolve in oils or organic compounds which are molecular and nonpolar in nature. Saturation: the point at which there is insufficient solvent to dissolve any more of the solute. Remember: Water is the universal solvent.

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Due Next Week Pre-lab # 1&2 pg11 Pre-lab # 5 pg 41 Pg 23 questions 1-4 omit #5 -7 Pgs Graph of Volume Vs. Mass data from table # 1 pg 35