Calculate the wavelength of the photon emitted when an electron makes a transition from n=4 to n=3. you can make use of the following constants: h=6.626×10^−34 j⋅s c=2.998×10^8 m/s 1 m=10^9 nm express your answer to four significant figures and include the appropriate units.

1875 nm

Explanation:

As per the data given:

                                  Initial orbit of electron = ni = 4

                                  Final orbit of electron = nf = 3.

As we know that,

                           Speed of electromagnetic waves = c = 3 × 10^8 m/s

                           Planck’s constant = h = 6.63 × 10^−34 Js.  

We will use Rydberg’s equation to get the wavelength or λ.

                                          1/λ=R (1/nf^2 – 1/ni^2)

Here, R= Rydberg Constant 1.0974x10^7 m-1;  λ is the wavelength;  n is equal to the energy level (initial and final)

                                           1/λ=R (1/nf^2 – 1/ni^2)

                                           1/λ =1.0974x10^7 (1/3^2 – 1/4^2)

                                           1/λ =1.0974x10^7 (1/9 – 1/16)

                                           1/λ =1.0974x10^7 (0.0486)

                                            1/λ=0.05333x 10^7

                                             λ= 1/ 0.05333x 10^7

                                             λ =1.875 x10^ -6m

Converting λ =1.875 x10^-6m to nanometers (nm )

                                               As, 1 m=10^9 nm                                  

                                               λ =1.875 x10^-6m x 10^9

                                                λ =1875 nm  

Note:

The value 1.0974x10^7 in the Rydberg equation comes from the Bohr equation and is equal to delta E / hc:  

delta E / hc = (2.18 x 10^-18 J) / (6.626 x 10^-34 J s)(3.00 x 10^8 m/s) = 1.0967 x 10^7

Hope it helps! :)

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.