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4 years ago

8

Classify these elements by whether they get oxidized or reduced in the reactions shown here: 2Ca(s)+ O 2 (g) F 2 (g)+2Li(s) → →

2CaO(s) 2LiF(s

1 answer:

Olegator [25]4 years ago

8 0

The calcium and the lithium are both classified as oxidized and the Fluorine and Oxygen are classified as reduced.
Hope this helps :)

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How many moles of sulfur will be needed to react with 5.00 grams of aluminum?

Pachacha [2.7K]

Answer:

9584738373848838e7e8e

6 0

3 years ago

A hydrogen atom in an excited state emits a photon of frequency ν = 3.084 x 1015 s-1. If the electron returns to the ground stat

VLD [36.1K]

<u>Answer:</u> The photon was emitted from the 4th energy level

<u>Explanation:</u>

To calculate the wavelength of light, we use the equation:

$\lambda=\frac{c}{\nu}$

where,

$\lambda$ = wavelength of the light

c = speed of light = $3\times 10^8m/s$

$\nu$ = frequency of light = $3.084\times 10^{15}s^{-1}$

Putting the values in above equation, we get:

$\lambda=\frac{3\times 10^8m/s}{3.084\times 10^{15}s^{-1}}=9.73\times 10^{-8}m$

To calculate the initial level, we use the equation given by Rydberg's equation, which is:

$\frac{1}{\lambda}=R_H\left(\frac{1}{n_f^2}-\frac{1}{n_i^2} \right )$

where,

$\lambda$ = Wavelength of radiation $9.73\times 10^{-8}m$

$R_H$ = Rydberg's Constant = $1.097\times 10^7m^{-1}$

$n_f$ = Final energy level = 1

$n_i$ = Initial energy level = ?

Putting the values, in above equation, we get

$\frac{1}{9.73\times 10^{-8}m}=1.097\times 10^7m^{-1}\left(\frac{1}{1^2}-\frac{1}{n_i^2} \right )$

$n_i=4$

Hence, the photon was emitted from the 4th energy level

4 0

3 years ago

At a certain temperature, the decomposition of NO2 is second order with a rate constant of 2.85 M-1min-1. If one starts with 1.7

alex41 [277]

Answer: It will take 0.50 minutes for it to decompose to 28.2% of its initial value

Explanation:

Integrated rate law for second order kinetics is given by:

$\frac{1}{a}=kt+\frac{1}{a_0}$

a= concentration left after time t = $\frac{28.2}{100}\times 1.77=0.50M$

k = rate constant = $2.85M^{-1}min^{-1}$

${a_0}$ = initial concentration = 1.77

t= time taken for decomposition

$\frac{1}{0.50}=2.85\times t+\frac{1}{1.77}$

$t=0.50min$

Thus it will take 0.50 minutes for it to decompose to 28.2% of its initial value

8 0

3 years ago

How many grams of water are contained in a 0.127 l sample at 20°c?

kvasek [131]

The density of water at 20 °C is 0.9982 g/cm^{3} or 998.2 g/L. The volume of water is 0.127 L thus, its mass can be calculated from the following formula:

d=\frac{m}{V}

Here, d is density, m is mass and V is volume of water.

On rearranging,

m=d×V=(998.2 g/L)(0.127 L)=126.7 g

Thus, mass of water is 126.7 g.

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3 years ago

80.0 grams of NaOH is dissolved in water to make a 6.00 L

jok3333 [9.3K]

Answer:

=0.333 M

Explanation:

40 g=1 mol

80 g=? the answer=2 mol

2 mol=6000

? =1000 litres

1000*2/6000=0.333 M

6 0

4 years ago