Calculating an initial Cr2O72-(aq) concentration of 1.0 x 10-3 M and an initial C2H5OH(aq) concentration of 0.500M?

Question

Olivia Anton · Accepted Answer

(d) At 1.50 min, #["Cr"_2"O"_7^"2-"] = 7.1 × 10^"-4"color(white)(l)"mol/L"#.
(e) Use an initial #["Cr"_2"O"_7^"2-"] = 5.0 × 10^"-4" color(white)(l)"mol/L"#.

(c) Determine the concentration The formula for absorbance #A# is given by Beer's Law: #color(blue)(bar(ul(|color(white)(a/a)A = epsiloncl color(white)(a/a)|)))" "# where #epsilon =# the molar absorptivity of the sample #c =# the concentration of the sample #l =# the path length through the cuvette It asserts that the absorbance and sample concentration are directly correlated. #A_2/A_1 = (color(red)(cancel(color(black)(epsilon)))c_2color(red)(cancel(color(black)(l))))/(color(red)(cancel(color(black)(epsilon)))c_1color(red)(cancel(color(black)(l)))) = c_2/c_1# This formula can be rearranged to provide #c_2 = c_1 × A_2/A_1# Regarding your issue, #c_1 = 1.0 ×10^"-3"color(white)(l) "mol/L"; A_1 = 0.782# #c_2 = ?; color(white)(mmmmmmml)A_2 = 0.553# ∴ #c_2 = 1.0 × 10^"-3"color(white)(l) "mol/L" × 0.553/0.782 = 7.1 × 10^"-4"color(white)(l)"mol/L"# (d) Selecting the new configuration You are aware of that #A = epsiloncl# #epsilon# is a constant that is characteristic of the sample. You want to keep #A_0# constant at 0.782. Thus, if you double the path length #l#, you must halve the concentration #c#. Commence with #c_0 = 1/2 × 1.0 × 10^"-3"color(white)(l) "mol/L" = 5.0 × 10^"-4"color(white)(l)"mol/L"#

Wyatt Atkins · Answer

undefined To calculate the initial concentration of Cr2O7^2- in a reaction with C2H5OH, you would need the balanced chemical equation and information about the reaction stoichiometry. Without this information, it's not possible to provide a specific answer.