The magnitudes (but not the signs) of the standard reduction potentials of two metals X and Y are Y21 1 2e2 Y 0 E0 5 0.34 V X21 1 2e2 X 0 E0 5 0.25 V where the 0 0 notation denotes that only the magnitude (but not the sign) of the E value is shown. When the half-cells of X and Y are connected, electrons flow from X to Y. When X is connected to a SHE, electrons flow from X to SHE. (a) Are the E values of the half-reactions positive or negative? (b) What is the standard emf of a cell made up of X and Y?
Principles of Chemistry: A molecular approach Chapter 2 Imaging and moving Gerd, Binning and Heinrich Roher -- experiment with electric current over a flat metal surface = tunneling current to view atoms Law of conservation of matter o Matter can neither created or destroyed Total reactant = total product Dalton - English chemist o Atomic theory of matter o Atoms are small, discrete, indivisible pieces of matter o Elements are made up of atoms o All atoms are the same Law of definite proportions o Same thing every time in same proportions Example: NaCl is always a 1:1 proportions Law of multiple proportions o 2 elements A and X can form different compounds when made in different proportions Ex: H2O and H2O2 or CO and CO2 Discovery of E- Thomson's charge to mass experiments with cathode rays o He believed these particles were building blocks of matter o Cathode ray particles = E- Atoms JJ Thomas and the Plum pudding model o Atoms are composed of a positive cloud of matter which e- are embedded in o This structure does not hold up today Rutherford o Gold foil experiment o Led to Discovery of the nucleus o Beam would go straight through the solid but some particles would veer off to the side It w