write the equation which describes the reaction between crystal violet and hydro
ID: 910513 • Letter: W
Question
write the equation which describes the reaction between crystal violet and hydroxide ion then answer the following questions :
A solution is prepared by mixing 25 ml of 8.44 x 10^-6 M crystal violet solution with 25 ml of a 10 M sodium hydroxide solution and diluted to a final volume of 100 mLs. Determine the limiting reagent.
After the reasction has gone to compleation calculate the conentration of all species in the reaction
How does the concentration of sodium hydroxie change over the course of the reaction? Explain this in terms of the inital concentrations of reactants.
Please answer all parts and show work.
Explanation / Answer
Crystal Violet + NaOH ----> Colorless product + Na+
According to the stoichiometry of the reaction 1 mole of crystal violet reacts with 1 mole of NaOH
Given,
The solution is prepared by mixing 25 ml of 8.44 x 10^-6 M crystal violet solution with 25 ml of a 10 M sodium hydroxide solution
Moles of Crystal Violet initially = molarity x volume (in L)
=> Moles = 8.44 x 10^-6 x 0.025 = 2.11 x 10^-7 moles
Moles of NaOH initially = 10 x 0.025 = 0.25 moles
Since 1 mole of crystal violet reacts with 1 mole of NaOH
2.11 x 10^-7 moles of crystal violet will react with 2.11 x 10^-7 moles of NaOH. Rest NaOH will be left over.
We see that crystal violet reacts completely and NaOH is in excess.
Hence the limiting reagent is Crystal Violet
Moles of colorless product formed = 2.11 x 10^-7 moles
Moles of NaOH left = 0.25 - 2.11 x 10^-7 = 0.25 moles(approx.)
Final Volume of solution = 100 mL = 0.1 L
=> [Colorless product] = 2.11 x 10^-7 / 0.1 = 2.11 x 10^-6 M
[NaOH] = 0.25 / 0.1 = 2.5 M
The conc. of NaOH at time (t) is C0 exp (-kt)
where
C0 = Initial conc. of NaOH
k = rate constant for the reaction
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