Illustrated Guide to Home Chemistry Experiments

72 DIY Science: Illustrated Guide to Home Chemistry Experiments

FIGURE 5-1: Hold the cap, rather than placing it on the bench

tapping the bottle to dispense only as much as you need, as

shown in Figure 5-2. Avoid letting the mouth of the bottle come

into contact with the weighing paper or any other object.

• Some solid chemicals are not free-flowing or tend to form
  clumps. If you are using such a chemical, there is sometimes
  no alternative but to scoop it out of the bottle. In such cases,
  the best way to avoid contamination is to use a disposable
  scoop and discard it immediately after use. Disposable plastic
  spoons are excellent and inexpensive one-use scoops. You can
  also modify a disposable Beral pipette by cutting diagonally
  across the bulb portion to form a disposable scoop, as shown
  in Figure 5-3.
  
  
  • Liquid chemicals may be transferred by using a funnel or
    by pouring directly from one container to another. When you
    transfer a liquid directly, use a clean stirring rod to prevent
    splashing or dripping, as shown in Figure 5-4.
  
  
  • For concentrated acids and other hazardous liquid chemicals,
    safety trumps the risk of contamination. Rather than risk
    pouring such hazardous chemicals into a measuring container,
    uncap the bottle and use a clean (ideally new) pipette to draw
    out as much of the liquid as you need. Recap the bottle and
    transfer the liquid from the pipette directly to the measuring,
    mixing, or storage container or directly to the reaction vessel.
  
  
  • Always recap the bottle immediately and replace the bottle in
    its assigned storage location.
  
  
  
  

If a chemical does become contaminated, do not attempt to

salvage it. Dispose of it properly and buy a new supply.

FIGURE 5-2: Tap solid chemicals directly onto the weighing paper

FIGURE 5-3: Use a modified Beral pipette as a scoop FIGURE 5-4: Using a stirring rod to transfer a liquid

Safety is always the primary consideration in proper

chemical handling. For detailed information about

storing and handling chemicals safely, see Chapter 4.

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