STANDARD OPERATING PROCEDURE: Storage and Handling of Alkali Metals

Oregon State University, Department of Chemistry
Standard Operating Procedure (SOP): Storage and Handling of Alkali Metals (ver. 1.0)
Author: Michael M. Lerner (michael.lerner@oregonstate.edu)
Safety Web Inception Date: 11/5/2013
Revised: N/A

Chemistry Department Safety Office: Gilbert Hall Room 153
Emergency Medical Services: 911
Campus Student Health Center: 7-9355
Poison Control: 9-1-800-222-1222
OSU Environmental Health and Safety: 7-2273
Public Safety & Oregon State Police: 7-7000

 A. Introduction

General: Pure alkali metals are shiny, soft and ductile at room temperature and silver in color, except Cs, which has a golden color. They can be easily cut with a knife due to their softness and then the shiny surface will readily oxidize, turning grey in color. All alkali metals are highly reactive and must be handled with great care; new users should work under the close supervision of an experienced co-worker. This SOP and relevant MSDS must be consulted before any work with alkali metals is attempted.

• MSDS for lithium (Li) metal [LINK]

• MSDS for sodium (Na) metal [LINK]

• MSDS for potassium (K) metal [LINK]

• MSDS for rubidium (Rb) metal [LINK]

• MSDS for cesium (Cs) metal [LINK]

B. Hazard identification, PPE, required safety equipment, and emergency response

B1. Hazards: All alkali metals react with water; the heavier metals reacting more vigorously than the lighter ones, releasing hydrogen gas and the corresponding metal hydroxides. Hydrogen released can cause a fire or an explosion with a presence of ignition sources (e.g. heat, sparks and flame). Fire will produce irritating, and/or toxic white fume that is highly corrosive to the lungs eyes and skin. Alkali metals react violently with carbon dioxide and carbon tetrachloride and also are incompatible with acids, organics, halogenated hydrocarbons, and plastic (e.g. Teflon and polyvinyl chloride).

B2. Personnal protective equipment (PPE): Appropriate eye and skin protection must be worn during all stages of any experiment involving an alkali metal, as follows:

(a) Eye protection: chemical splash goggles or safety glasses that meet ANSI standard Z-87.1 must worn whenever handling alkali metals. Ordinary prescription eye glasses will not provide the necessary level of protection unless they also meet the same ANSI standard. A face shield, worn over safety eye wear, is required in addition if there is a possible risk of explosion.

(b) Skin and body protection: chrome leather gloves or appropriate rubber gloves should be worn when handling alkali metals. MSDS for specific chemicals to be used should be consulted for direction on which glove type is recommended. A fire resistant fully-buttoned knee-length laboratory coat must be worn to protect the body. In addition, fully enclosed shoes which cover the entire foot (with no holes in the top) must be worn.

B3. Engineering controls and other safety equipment: All manipulation of alkali metals must be conducted inside a well vented fume hood with the sash level at the lowest height possible to perform the required operations. Before starting work, clear the fume hood of any unnecessary equipment or chemicals. An eyewash/safety shower station should be within a ten second travel time of the site of the experiment. Familiarize yourself with the location of this important safety equipment and check that the eyewasher is functioning (pass water through it until it runs clear) and that the safety shower passed a recent inspection (within last 12 months). Also before starting work, know the location of the nearest fire extinguisher and fire alarm pull station and check that the fire extinguisher passed recent inspection and that it is not empty.

B4. Emergency response: Fire is the most likely accident, be well prepared for this eventuality and also know the correct response in the event of a reagent spill. Small fires caused by the ignition of alkali metals are best tackled with an ABC-type (powder based) fire extinguisher. DO NOT use a carbon dioxide or a water based units; alkali metals react violently with these media. As with any incident involving fire, raise the alarm as soon as possible (engage pull station alarm, call, or have someone else call, 911), and escape the vicinity of the fire if you have any doubts whatsoever that you will be unable to quickly extinguish the blaze successfully. Pull down the fume hood sash, close the door of the laboratory (but do not lock it), as you exit.

C. Procedures for the safe handling of alkali metals

C1. General: Before commencing any experiment involving an alkali metal ensure that the fume hood to be used is clear of clutter and that any unnecessary potentially combustible materials have been removed (REMEMBER, fume hood space should never be used for solvent storage). Appropriate PPE must be worn and other safety equipment as detailed above should be in place and in good working order (Section B).

C2. Storage: Alkali metals are usually stored under an inert atmosphere and/or mineral oil. Keep them away from heat and sources of ignition.

C3. Handling: Due to their high reactivity towards air and water, all equipment, solvents and chemicals need to be dry. Avoid contact with incompatible materials; oxidizing agents, acids, moisture. Conduct all experiments on a small scale (generally < 2 g scale). Control the reaction rate by addition of the alkali metal in small increments. Handle alkali metals with care under an inert atmosphere (Ar or N2; note, however, that lithium metal will corrode under N2).

C4. Disposal of residual reagents: To dispose of alkali metals safely, isopropanol is used to dissolve small quantities (< 2 g) of the metal in a fumehood (hydrogen gas will be slowly evolved). Good ventilation should be provided. EH&S should be contacted if larger amounts of alkali metal (>1-2 g) are to be disposed of. If in any doubt whatsoever as to the proper and safe manner with which to quench a given reagent, contact OSU Environmental Health and Safety and request a waste chemical pick-up. Representatives from EH&S will remove and dispose of any PROPERLY LABELED chemicals without direct charge upon completion of the following web request form [LINK].

Small amounts (< 1 g) of Li metal (ONLY Li, NOT any other alkali metals!) can be safely destroyed by holding small pieces under cool water with tongs so that the metal is completely submerged until it fully reacts with the water.

This chemical safety advisory document was prepared solely for the use of researchers affiliated to Oregon State University. As stated above (Section A), the content is designed to inform on good working practices and it is not intended to replace hands-on practical training in the techniques described. It is the responsibility of the Principal Investigator to see to it that his/her co-workers are properly trained and informed on hazard management, including the possibility of customization of the information herein as appropriate to meet specific needs. Neither Oregon State University, nor any of its employees (including the author), makes any warranty, express of implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, or represents that its use would not infringe privately owned rights. Reference herein to any specific commerical product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by Oregon State University.

last update: 11/5/13 (PRB)