Chemistry, 20.07.2019 05:00 cardonaalfredo

How concentrated can lye solution be before its ph rises above calcium hydroxide saturated water?

Answers: 1

Show answers

Answers

Answer from: gordon57

The solubility of calcium hydroxide (Ca(OH)2) in water at $20^{o}C$ is 0.02335 mol/L. When a Ca(OH)2 solution has a concentration of 0.02335 mol/L at the said temperature, a saturated solution is formed.

Upon dissolution and dissociation of 1 mole Ca(OH)2, 1 mole of calcium ion ( $Ca^{+2}$ ) and 2 moles of hydroxide ions ( $OH^{-1}$ ) are formed. The concentration of the hydroxide ions determine the pH of the solution. This same concentration would be needed in calculating the concentration of lye solution needed.

1. To calculate the pH of the solution, a few approaches are possible. Here, the pOH of the solution is calculated first using the molar concentration of $OH^{-1}$ ions. Because pH + pOH = 14, the pH of the solution can then be calculated by subtracting pOH from 14.

Because 2 moles of $OH^{-1}$ ions are formed per mole of Ca(OH)2 dissolved, the pOH of a saturated Ca(OH)2 solution at $20^{o}C$ is,

*Concentration ( $C_{OH_{1}}$ ) of $OH^{-1}$ ions,
$C_{OH_{1}}$ = 0.02335 mol Ca(OH)2/L * 2 mol $OH^{-1}$ / 1 mol Ca(OH)2
$C_{OH_{1}}$ = 0.0467 mol $OH^{-1}$ /L

*pOH of saturated Ca(OH)2 solution,
    pOH = -log [ $C_{OH_{1}}$ ]
  pOH = -log [0.0467 mol $OH^{-1}$ /L ]
  pOH = 1.33

*pH of saturated Ca(OH)2 solution,
      pH = 14 - 1.33
  pH = 12.67

2. To find the concentration of lye (NaOH) solution that would give the same pH as a saturated Ca(OH)2 solution at the same temperature, the pOH of the saturated Ca(OH)2 solution will be used.

For every mole of NaOH that dissolves and dissociates, 1 mole of $OH^{-1}$ ions is formed. Thus,

*Concentration ( $C_{OH_{2}}$ ) of $OH^{-1}$ ions,
pOH = -log [ $C_{OH_{2}}$ ]
   1.33 = -log [ $C_{OH_{2}}$ ]
   $C_{OH_{2}}$ = 10^-1.33
   $C_{OH_{2}}$ = 0.0467 mol $OH^{-1}$ / L

Because 1 mole of NaOH produces only 1 mole of $OH^{-1}$ ions, the concentration of the $OH^{-1}$ ions should then be equal to the concentration of the lye (NaOH) solution. Thus, 0.0467 mol/L of lye would give the same pH as that of 0.0233 mol/L (saturated) Ca(OH)2 solution at $20^{o}C$ . The pH of both solutions is 12.67.

Answer from: Quest

The answer options is d

Answer from: Quest

that tool would be a compass

Another question on Chemistry

Chemistry, 21.06.2019 23:00

The wave shown on the electromagnetic spectrum disturb the medium it passes through a)different frequency. b)the same frequency .

Answers: 2

Answer

Chemistry, 22.06.2019 09:10

Which class of molecules functions as chemical signals? hormones water carbohydrates proteins

Answers: 1

Answer

Chemistry, 22.06.2019 13:00

One of the hopes for solving the world's energy problem is to make use of the fusion reaction 21h +31h --> 42he + 10n + energy how much energy is released when 1 mol of deuterium is fused with 1 mol of tritium according to the above reaction? the masses of the atoms and the neutrons are as follows: 21h = 2.0140 amu 31h = 3.01605 amu 42he = 4.002603 amu 10n = 1.008665 amu. the speed of light is 2.9979 x 108 m/s.

Answers: 1

Answer

Chemistry, 22.06.2019 23:00