Calculate the wavelength in nanometers of the light emitted by a hydrogen atom when it's electron falls from the n= 7 to the n= 4 principal energy level. Recall that the engergy levels of the H atom are given by En = -2.18 x 10 to the negative 18 J ( 1/n to the second power) . ( c= 3.00 x 10 to to the 8 th power m/s ; h=6.63 x 10 to the negative 34 j. s

2.165 x 10^3 nm.

Explanation:

Using Rybergs equation,

1/lambda = R * (1/n1^2 - 1/n2^2)

Where,

R = rybergs constant = 109737.32 cm^-1

n1 = 7

n2 = 4

= 109737.32 * (1/7^2 - 1/4^2)

= 4619.05

Lambda = 2.165 x 10^-4 cm

Since 100 cm = 1m, 1 nm = 10^-9 m

= 2.165 x 10^-4 cm * 1 m/100 cm * 1 nm/10^-9 m

= 2.165 x 10^3 nm.

answer: the value of enthalpy change will be -152.80 kj.

solution:

pressure = 1atm , temperature = = 298 k

given that pressure and temperature are same in both gases , the number of moles of both gases can be determined by the ideal gas equation.

according to reaction 3 moles no are reacting with 1 mol of ,then 0.49 mol of no will react with moles of ozone that is 0.16 moles of ozone. since, no is limiting reagent and is an excessive reagent.

enthalpy change for the reaction between the given volumes of the gases is :

answer:

the reaction is type of combination reaction.

explanation:

on the product side, there are 2 molecules of bonded to fe   which means one atom of fe are combined two molecules of . so, balanced chemical equation becomes :

this reaction follows the reaction type of combination reaction. a combination reaction is defined as chemical reaction in which reactants combines together to form a single product.