Chem 1212L Quiz 7

Calculate the initial concentrations of Fe3+ ions when these solutions are mixed: 6.00 mL of 0.00180 M KSCN, 5.00 mL 0.240 M Fe(NO3)3 and 14.00 mL of 0.050 M HNO3.

0.0480 M

Some of the goals of the experiment include ( Select all that apply ) Question options: -calibrate a spectrophotometer -use the quadratic formula in equilibrium constant calculations -create an ICE table -find the equilibrium contant for H2 (g)+ 1/2 O2 (g) ---> H2O (g) -convert correctly from transmittance to absorption

-calibrate a spectrophotometer -use the quadratic formula in equilibrium constant calculations -create an ICE table -convert correctly from transmittance to absorption

Calculate the initial concentrations of SCN- ions when these solutions are mixed: 6.00 mL of 0.00180 M KSCN, 5.00 mL 0.240 M Fe(NO3)3 and 14.00 mL of 0.050 M HNO3.

4.32 x 10^-4

If you assume this reaction is driven to completion because of the large excess of one ion, what is the concentration of [Fe(SCN)]2+ that would be formed from 6.00 mL of 0.00180 M KSCN 5.00 mL 0.240 M Fe(NO3)3 and 14.00 mL of 0.050 M HNO3.

4.32 x 10^-4

A student prepared this solution by mixing the following solutions: 4.00 mL of 0.00250 M Fe(NO3)3 3.00 mL of 0.00250 M KSCN 3.00 mL of 0.050 M HNO3 From a plot of absorbance versus concentration of [Fe(SCN)]2+, the equilibrium concentration of [Fe(SCN)]2+ was determined to be 2.8 x 10-4 M. Calculate the equilibrium constant.

827

The reading from the spectrometer should be made in transmittance and converted to absorbance because?

Transmittance is linear.

A student prepared this solution by mixing the following solutions: 4.00 mL of 0.00250 M Fe(NO3)3 3.00 mL of 0.00250 M KSCN 3.00 mL of 0.050 M HNO3 From a plot of absorbance versus concentration of [Fe(SCN)]2+, the equilibrium concentration of [Fe(SCN)]2+ was determined to be 2.8 x 10-4 M. Calculate the initial concentration of Fe3+ before the system is allowed to proceed to equilibrium.

1.00 x 10^-3

A student prepared this solution by mixing the following solutions: 4.00 mL of 0.00250 M Fe(NO3)3 3.00 mL of 0.00250 M KSCN 3.00 mL of 0.050 M HNO3 From a plot of absorbance versus concentration of [Fe(SCN)]2+, the equilibrium concentration of [Fe(SCN)]2+ was determined to be 2.8 x 10-4 M. Calculate the initial concentration of SCN- before the system proceeds to equilibrium.

7.50 x 10^-4

All the information should be written in your lab notebook and not on the sheets provided. What will you be determining and writing in your lab book?

I will be reporting the transmission values in my notebook and then convert them afterwards to absorbance using the formula A=2-log(%T).

All the information should be written in your lab notebook and not on the sheets provided. What will you be doing for the calculations?

I will graph using Excel the absorbance versus the concentrations given and using the slope to back calculate the concentration from the observed absorbance.