Calculate the ph of a solution containing 0.75 m lactic acid and 0.25 m sodium lactate. recalculate after the addition of 0.05ml of hcl

pH= pKa+log[A-]/[HA]

pKa=-log(Ka)

-log(1.4/10^-4) (the Ka of lactic acid)

pKa=3.85

pH=3.85+log (0.25/.75)

pH=3.37

HCl is an acid, so the 0.05M HCl is added to the acid and subtracted from the base

pH= 3.85+ log(0.24/0.76)

pH=3.35 after addition of HCl

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3