Pre-Lab: Silver Nanoparticles

Name(Print then sign): ______

Partner(Print): ______

Lab Day: ______Section: ______TA______

This assignment must be completed individually and turned in to your TA at the beginning of lab. You will not be allowed to begin the lab until you have completed this assignment.

In this lab you will be making use of a couple of equations, the first was developed by Max Planck who assumed that energy can be either released or absorbed by atoms in discrete ‘chunks’ of some minimum size. He coined the term ‘quantum’ meaning ‘fixed amount’ to the smallest quantity of energy that can be emitted or absorbed as electromagnetic radiation.

E = hc /λ

Where E=energy, h= Planck’s constant, 6.626 x 10-34 J.s (interestingly it is one of the smallest constants in Physics), c= speed of light, 3×108 meters per second, λ = wavelength in nm – Chapter 6.

And the Beer-Lambert Law

A=log(I0/I)=-log(T)=ecl

Where A = absorbance, no units, I = light signal with sample, I0 = light signal with reference, T = fraction of transmitted light (I/I0), absorption(extinction) coefficient, e in L mol-1 cm-1 , c = concentration, mol L-1 , l = path length in cms – Chapter 14.

1.  What wavelengths correspond to the visible region of the electromagnetic spectrum?

2.  Of the following, ______radiation has the shortest wavelength

A. X-Ray B. radio C. microwave D. ultraviolet

E. infrared

3.  Electromagnetic radiation with a wavelength of 525 nm appears as green light to the human eye. The frequency of this light is ______s-1.Circle the correct one.

A. 5.71x 1014 B. 5.71x 105 C. 1.58x 102 D. 1.58x 1011 E. 1.75x 10-11

4.  Electromagnetic radiation with a wavelength of 640 nm appears as orange light to the human eye. The energy of one photon of this light is ______J? Circle the correct one.

A. 1.272x 10-31 B. 3.106x 10-28 C. 3.106x 10-19 D. 1.272x 10-22

E. 3.220x 1018

5.  Give at least four limitations of the Beer-Lambert law

6. If an absorbance of CuSO4 was found to be 0.34, what is the calculated molarity of the solution given that Є = 2.75 M-1cm-1and b = 1cm?

7.  Compute the molar absorptivity of the CuSO4 given that the A = 0.239, b= 1cm and c= 0.02 M?