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3 years ago

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rank the group 1a elements tested in order of increasing energy emission when electrons returns to the ground state. explain thi

s pattern in terms of changes in energy levels.

1 answer:

labwork [276]3 years ago

3 0

<em>Answer:</em>

The increasing order of energy emission is as follow

Li < Na < K < Rb < Cs

<em>Explanation:</em>

The Characteristic colors of alkali metals are

Li-crimson<em> red</em>
Na- golden<em> yellow</em>
K- pale <em>violet</em>
Rb and Cs- <em>violet</em>

These flame color show that when we moved from down the group, the wavelength decreases (frequency increases).
As the color of Li is red that shows ,it has less emission energy as compare to Rb and Cs that have color violet (more emission energy).

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2 years ago

If your conclusion does not agree with (disproves) your hypothesis:

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If your findings disproves your hypothesis then your hypothesis is probably wrong.

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3 years ago

for the reaction 2Fe + O2 = 2FeO, how many grams of iron oxide are produced from 8.00 mol of iron? when o2 is an excess

Luba_88 [7]

Answer:

2Fe + O₂ -------------------> 2FeO

8 mol Fe produce

8 mol Fe * 2 mol FeO / 2 mol Fe = 8 mol FeO

Mass of FeO = 8 mol FeO * 71.85 g/mol = 574.8 grams FeO

Explanation:

Having 8 mol of Iron means 8 moles of iron oxide can be produced. Each mole of iron oxide has a molecular weight of 71.85 grams. Therefore, 8 moles of iron oxide should weight 574.8 grams.

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3 years ago

If 31.6 g of KMnO4 is dissolved in enough water to give 160 mL of solution, what is the molarity?

Zina [86]

Answer:

A. 1.25M

B. 19.98g

Explanation:

A. Data obtained from the question include the following:

Mass of KMnO4 = 31.6 g

Volume = 160 mL

Molarity =..?

We'll begin by calculating the number of mole KMnO4 in the solution. This is can be obtained as follow:

Mass of KMnO4 = 31.6 g

Molar mass of KMnO4 = 39 + 55 + (16x4) = 158g/mol

Number of mole of KMnO4 =..?

Mole = mass /Molar mass

Number of mole of KMnO4 = 31.6/158 = 0.2 mole

Now, we can obtain the molarity of the solution as follow:

Volume = 160 mL = 160/1000 = 0.16L

Mole of KMnO4 = 0.2 mole

Molarity = mole /Volume

Molarity = 0.2/0.16 = 1.25M

B. Data obtained from the question include the following:

Volume = 300mL

Molarity = 0.74 M

Mass of H2C2O4 =..?

First, we shall determine the number of mole H2C2O4. This is illustrated below:

Volume = 300mL = 300/1000 = 0.3L

Molarity = 0.74 M

Mole of H2C2O4 =?

Mole = Molarity x Volume

Mole of H2C2O4 = 0.74 x 0.3

Mole of H2C2O4 = 0.222 mole

Now, we can easily find the mass of H2C2O4 by converting 0.222 mole to grams as shown below:

Number of mole of H2C2O4 = 0.222 mole

Molar mass of H2C2O4 = (2x1) + (12x2) + (16x4) = 2 + 24 + 64 = 90g/mol

Mass of H2C2O4 =..?

Mass = mole x molar mass

Mass of H2C2O4 = 0.222 x 90

Mass of H2C2O4 = 19.98g

5 0

3 years ago

How are half life and radioactive decay related

hoa [83]

Answer : Half life and radioactive decay are inversely proportional to each other.

Explanation :

The mathematic relationship between the half-life and radioactive decay :

$N=N_oe^{-\lambda t}$ ................(1)

where,

N = number of radioactive atoms at time, t

$N_o$ = number of radioactive atoms at the beginning when time is zero

e = Euler's constant = 2.17828

t = time

$\lambda$ = decay rate

when $t=t_{1/2}$ then the number of radioactive decay become half of the initial decay atom i.e $N=\frac{N_o}{2}$ .

Now substituting these conditions in above equation (1), we get

$\frac{N_o}{2}=N_oe^{-\lambda t_{1/2}}$

By rearranging the terms, we get

$\frac{1}{2}=e^{-\lambda t_{1/2}}$

Now taking natural log on both side,

$ln(\frac{1}{2})=-\lambda \times t_{1/2}$

By rearranging the terms, we get

$t_{1/2}=\frac{0.693}{\lambda}$

This is the relationship between the half-life and radioactive decay.

Hence, from this we conclude that the Half life and radioactive decay are inversely proportional to each other. That means faster the decay, shorter the half-life.

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3 years ago