A is a 0.5M KOH solution, while B is a solution obtained after idm' of 0.75M HCI reacted with 30g of a powdered sample of “limestone” soil. (a) Put B into the burette and titrate it against 20.00cm or 25.00cm' portions of solution A in a conical flask using phenolphthalein as indicator. Repeat the procedure two or more times to obtain consistent titre values. Record and tabulate your results and hence calculate your average titre. (b) From your table and the information given above, calculate the; (i) The initial moles of the HCl solution (B). (ii) Moles of the KOH reacting. (iii) Final moles of B (excess). (iv) Moles of HCl that reacted with the soil sample. (v) Moles of CaCO3 in the soil sample. (vi) Mass of the CaCO3 in the soil sample. (vii) Percentage of CaCO3 in the soil sample.

in chemistry, a solution’s concentration is how much of a dissolvable substance, known as a solute, is mixed with another substance, called the solvent. the standard formula is c = m/v, where c is the concentration, m is the mass of the solute dissolved, and v is the total volume

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.