# Homework Help: Calculate Rh value from Rydberg Equation

1. Oct 29, 2013

### WK95

1. The problem statement, all variables and given/known data
λ for one line of the hydrogen spectrum is .4118 x 10-4 cm. Use this value in the Rydberg equation to calculate the RH value using n1 = 2, and n2 = 3.

2. Relevant equations
$\frac{1}{ \lambda } = \frac{R_{h}}{hc} ( \frac{1}{n_{x}^{2}}-\frac{1}{n_{y}^{2}})$
$\frac{1}{ \lambda } = R( \frac{1}{n_{x}^{2}}-\frac{1}{n_{y}^{2}})$
$\lambda = 0.4118 x 10^{-4} cm= 4.118 x 10^{-5} cm = 4.118 x 10^{-7}m$
$x_{1} = 2$
$X_{2} = 3$
$h=6.626 x 10^{-34} J*s$
$c=2.998 x 10^{8} m/s$

3. The attempt at a solution
$\frac{1}{4.118 x 10^{-7}m} = \frac{R_{h}}{(6.626 x 10^{-34} J*s)(2.998 x 10^{8} m/s)} ( \frac{1}{2^{2}}-\frac{1}{3^{2}})$
$R_{h}=3.473x10^{-18}$
This is wrong however

2. Aug 14, 2017

### TeethWhitener

This is the right answer as far as I can tell. Maybe your answer got auto-rejected from a web-based homework form for the wrong number of sig figs?

3. Aug 14, 2017

Or they might want an $E$ in place of your $x$. $R_H$ needs to be defined, and what units are they looking for=SI/MKS or electron-volts? The statement of the problem appears to be poorly defined. (A google showed this same question appeared on the Chem Forums website.)