Which is a correct laboratory technique? * The minimum number of centrifuge tubes in a centrifuge machine during its operation is one. An open flame is the heat source for heating or evaporating flammable liquids. Never place reagents directly onto the weighing pan of a balance, always use weighing paper, a beaker, or some other container. Water or glycerol should not be applied to the glass tubing and to the hole in the rubber stopper before inserting the glass tubing.

Which is a correct laboratory technique? * The minimum number of centrifuge tubes in a centrifuge machine during its operation is one. An open flame is the heat source for heating or evaporating flammable liquids. Never place reagents directly onto the weighing pan of a balance, always use weighing paper, a beaker, or some other container. Water or glycerol should not be applied to the glass tubing and to the hole in the rubber stopper before inserting the glass tubing.

World of Chemistry

7th Edition

ISBN:9780618562763

Author:Steven S. Zumdahl

Publisher:Steven S. Zumdahl

Chapter1: Chemistry: An Introduction

Section: Chapter Questions

Problem 8A

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You obtain an Unknown Sample from the Stockroom. You begin testing the solution through the steps outlined in the flowchart of the experiment’s PDF file. You first add HCl and centrifuge your mixture. You observe the formation of a white precipitate in the bottom of the test tube. After pouring off the supernatant liquid, you add hot water to the white precipitate. Addition of the hot water dissolves some of the precipitate, but some white precipitate still remains on the bottom of the test tube. Which of the following is a valid conclusion to draw at this point? Pb2+ is definitely present. Hg22+ is definitely present. Ag+ could be present, or Hg22+ could be present, or BOTH could be present. Ag+ is definitely present
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