The answer would be periods 6-7 :)
[H_{3}O^{+}] = 0.00770 M
The equilibrium equation representing the dissociation of 

Given [H_{3}O^{+}] = 0.00770 M
Let the initial concentration of acid be x and change y
So y =
=
= 0.00770 M



0.00257 x - 0.00001979 = 0.00005929
x = 0.031 M
Therefore, initial concentration of the weak acid is <u>0.031 M</u>
We first assume that this gas is an ideal gas where it follows the ideal gas equation. The said equation is expressed as: PV = nRT. From this equation, we can predict the changes in the pressure, volume and temperature. If the volume and the temperature of this gas is doubled, then the pressure still stays the same.
Hey there !
Molecular Weight: 262.86 g/mol
Volume in liters : 1,000 mL => 1,000 / 1000 => 1 L
Number of moles of solution :
number of moles = volume x molarity
number of moles = 1 x 0.3 => 0.3 moles
Therefore:
1 mole Mg₃(PO₄)₂ ------------------- 262.86 g
0.3 moles ----------------------------- mass of Mg₃(PO₄)₂ ??
mass of Mg₃(PO₄)₂ = 0.3 x 262.86 / 1
mass of Mg(PO₄)₂ => 78.858 g
Hope this helps!