Answer:
0.109 g.
Explanation:
Equation of the reaction:
Na3PO4 + 3HCl --> 3NaCl + H3PO4
Number of moles of HCl = molar concentration × volume
= 0.1 × 0.04
= 0.004 mol.
By stoichiometry, 1 mole of Na3PO4 neutralises 3 moles of HCl. Therefore, number of moles of Na3PO4 = 0.004/3
= 0.0013 mol
Mass of Na3PO4 = molar mass × number of moles
= 0.0013 × 164
= 0.219 g
Since 50% of Na3PO4 was present in the sample. Let 100 g be the total mass of the substance
= 0.219 × 50 g/100 g
= 0.109 g.
Given is the ratio of conjugate base and conjugate acid of phosphoric acid. pH of a substance is the concentration of the hydrogen ions in its solution and higher this concentration lower is the value of pH.
pKa value is a measure of the strength of acid, it is the negative log of acid dissociation constant Ka.
Answer:
a. Be and Mg
Explanation:
Be (beryllium) and Mg (magnesium) are both found in the alkaline earth metals family (group 2) on the periodic table. Elements in the same family or group have similar properties,
Ca and Br are in groups 2 and 17
Cl and Ar are in groups 17 and 18
Na and P are in groups 1 and 15