Aphosphate buffer solution (25.00 ml sample) used for a growth medium was titrated with 0.1000 m hydrochloric acid. the components of the buffer were sodium monohydrogenphosphate and sodium dihydrogenphosphate. the first endpoint occurred at a volume of 10.32 ml, and the second occurred after an additional 18.62 ml was added, for a total volume of 28.94 ml. what was the total concentration of phosphate (in any form) in the buffer?

0,07448M of phosphate buffer

Explanation:

sodium monohydrogenphosphate (Na₂HP) and sodium dihydrogenphosphate (NaH₂P) react with HCl thus:

Na₂HP + HCl ⇄ NaH₂P + NaCl (1)

NaH₂P + HCl ⇄ H₃P + NaCl (2)

The first endpoint is due the reaction (1), When all phosphate buffer is as NaH₂P form, begins the second reaction. That means that the second endpoint is due the total concentration of phosphate that is obtained thus:

0,01862L of HCl×= 1,862x10⁻³moles of HCl ≡ moles of phosphate buffer.

The concentration is:

= 0,07448M of phosphate buffer

I hope it helps!

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.