Student A rinsed three (3) Erlenmeyer flasks with distilled water and, then, to each was added a 25.00-mL aliquot of dilute hydrochloric acid, HCl(aq) . The solution was titrated to a bromothymol blue end point with standardized aqueous sodium hydroxide, NaOH9aq). Student B, his lab partner, challenged his titration results because Student A failed to wash the Erlenmeyer flask with the HCl solution of unknown concentration. A) Student A is correct because the moles of analyte is related to the HCl aliquot’s volume.

B) Student A made an error since the additional wáter alters the titration’s end point.

C) Student B is correct because moles of analyte are altered by the diluting wáter drops.

D) Student B is not correct because the bromothymol blue indicator is added to the buret.

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.