Adjust the standard sample using a precision electronic balance

Topic outline

• General

  Collapse all Expand all
  • 

    Japanese URL

• How to use precision electronic balances
  • 
    

    Cases using precision electronic balances
    
    1) When preparing solutions with accurate concentrations such as standard samples
    
    2) When testing the capacity of a whole pipette or burette
    
    3) Weight measurement of environmental samples (filters that filter particulates in water or air, etc.)

    
    

    [How to prepare standard sample]

    　When creating a standard sample with a certain target concentration (x mol/L), it is often not necessary to adjust it to the exact target concentration, such as x.0000 mol/L. Even if it is slightly off, such as x.10354 mol/L, it is important to accurately determine the adjusted concentration.

    　Because it takes time to make measurements using precision electronic balances, student experiments often have long lines for precision balances. Therefore, first weigh the reagents using a regular electronic balance (installed on a desk by the side of the classroom), and then weigh them using a precision electronic balance.
    
    
    

    
    

    
    

  • 

    ➀秤量瓶の風袋重量を測定Measuring the tare weight of a weighing bottle　精密電子天秤precision electronic balance　

    ➁試料を量り取るWeigh the sample　普通天秤Ordinary balance　

    ③試料重量を精密測定Accurately measure sample weight

    ・秤量瓶をよく乾燥させるDry the weighing bottle thoroughly　

    ・天秤のフードの窓を閉めるClose the balance hood window　

    ・振動を与えないdo not give vibration　

    ・表示が安定するまで待つWait until the display stabilizes
    

  • 
    

    　Transfer the entire amount of reagent weighed out on a balance to a volumetric flask. You can also transfer the reagent by placing a funnel over the mouth of the volumetric flask and pouring water into it.

    　You can also put the reagent in a beaker, let it dissolve to some extent in the beaker, and then pour it into the volumetric flask.
    
    After it is completely dissolved, add water to the volumetric flask up to the mark.

    　(When the powder reagent dissolves in water, the volume of water + powder reagent becomes smaller.)

    ★　Mix carefully and carefully while holding down the stopper of the volumetric flask. Please flip up and down 20 times. Beginners often fail because they are not flexible enough and adjust reagents with uneven concentrations.

    ★　Do not stopper the volumetric flask with exothermic reagents in it. The air inside the volumetric flask heats up and expands, causing the stopper and liquid to splatter.

    
    

    

    ④試薬をメスフラスコへ移すTransfer reagents to volumetric flask　小さめビーカーsmall beaker　イオン交換水ion exchange water　秤量瓶の洗液もビーカーへThe washing liquid from the weighing bottle is also transferred to the beaker.　洗液もメスフラスコへThe washing liquid is also transferred to the volumetric flask.　

    ⑤メスアップしてよく混ぜるMix well　上下転倒フリフリ20回Flipping up and down 20 times　

    発熱する試薬をメスフラスコで溶かすのはNG!　It is no good to dissolve reagents that generate heat in a volumetric flask.　

    メスフラスコの空気が膨張Air in volumetric flask expands　栓と液体が飛び散るStopper and liquid splash　放熱してからAfter dissipating the heat.