How does the sky appear blue? (BONUS QUESTION)!!!!
2 answers:
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Answer:
Therefore the coins were of yellow brass.
Explanation:
A sample weighted 129.6 g and had a volume of 15.3 cm³.
Here mass= 129.6 g and volume =15.3 cm³.
g/cm³
=8.47 g/cm³
Given that the density of gold = 19.3 g/cm³
and density of yellow brass = 8.47 g/cm³
Since the density of the sample is equal to the density of yellow brass.
Therefore the coins were of yellow brass.
The solubility of calcium hydroxide (Ca(OH)2) in water at 
is 0.02335 <span>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 (</span>
) and 2 moles of hydroxide ions (
) 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 ions. Because pH + pOH = 14, the pH of the solution can then be calculated by subtracting pOH from 14.
Because 2 moles of ions are formed per mole of Ca(OH)2 dissolved, the pOH of a saturated Ca(OH)2 solution at is,
*Concentration (
) of ions,
= 0.02335 mol Ca(OH)2/L * 2 mol / 1 mol Ca(OH)2
= 0.0467 mol /L
*pOH of saturated Ca(OH)2 solution,
pOH = -log []
pOH = -log [0.0467 mol/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 ions is formed. Thus,
*Concentration (
) of ions,
pOH = -log []
1.33 = -log [ ]
= 10^-1.33
= 0.0467 mol / L
Because 1 mole of NaOH produces only 1 mole of ions, the concentration of the 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 . The pH of both solutions is 12.67.
Upon dissolution and dissociation of 1 mole Ca(OH)2, 1 mole of calcium ion (</span>
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
Because 2 moles of
*Concentration (
*pOH of saturated Ca(OH)2 solution,
pOH = -log [
pOH = -log [0.0467 mol
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
*Concentration (
pOH = -log [
1.33 = -log [
Because 1 mole of NaOH produces only 1 mole of