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3 years ago

How can you tell that a chemical change has occurred?

Chemistry

1 answer:

Alik [6]3 years ago

5 0

A. The products of the change are different from the starting

substances.

Explanation:

Whenever there is a physical change it may just affect the phase change but the properties remains the same. Whenever there is an occurrence of a chemical change, it was indicated by some of these things such as,

The products are exactly different from the products.

Chemical properties of these reactants are entirely different from that of the products.

Chemical composition as well as the physical properties of the reactants and the products will change

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Th e molar absorption coeffi cient of a substance dissolved in water is known to be 855 dm3 mol−1 cm−1 at 270 nm. To determine t

Olegator [25]

Answer : The percentage reduction in intensity is 79.80 %

Explanation :

Using Beer-Lambert's law :

$A=\epsilon \times C\times l$

$A=\log \frac{I_o}{I}$

$\log \frac{I_o}{I}=\epsilon \times C\times l$

where,

A = absorbance of solution

C = concentration of solution = $3.25mmol.dm^{3-}=3.25\times 10^{-3}mol.dm^{-3}$

l = path length = 2.5 mm = 0.25 cm

$I_o$ = incident light

$I$ = transmitted light

$\epsilon$ = molar absorptivity coefficient = $855dm^3mol^{-1}cm^{-1}$

Now put all the given values in the above formula, we get:

$\log \frac{I_o}{I}=(855dm^3mol^{-1}cm^{-1})\times (3.25\times 10^{-3}mol.dm^{-3})\times (0.25cm)$

$\log \frac{I_o}{I}=0.6947$

$\frac{I_o}{I}=10^{0.6947}=4.951$

If we consider $I_o$ = 100

then, $I=\frac{100}{4.951}=20.198$

Here 'I' intensity of transmitted light = 20.198

Thus, the intensity of absorbed light $I_A$ = 100 - 20.198 = 79.80

Now we have to calculate the percentage reduction in intensity.

$\% \text{reduction in intensity}=\frac{I_A}{I_o}\times 100$

$\% \text{reduction in intensity}=\frac{79.80}{100}\times 100=79.80\%$

Therefore, the percentage reduction in intensity is 79.80 %

3 0

4 years ago

Eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

otez555 [7]

Answer:

<h3>option D</h3>

Explanation:

<h3>Is wire A connected to the light bulb </h3>

<h3>because it is series connection</h3>

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3 years ago

Why is conical flask used in the freezing point of naphthalene activity?

SpyIntel [72]

Answer:

D. To ensure the cooling process is not affected by surrounding temperature

Explanation:

The conical flask acts as a temperature jacket.

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3 years ago

A) Atom is generally charge less, why?

Aliun [14]

Answer:

Explanation:

Every atom has no overall charge (neutral). This is because they contain equal numbers of positive protons and negative electrons. These opposite charges cancel each other out making the atom neutral.

7 0

3 years ago

Hợp chất nào có khả năng là hợp chất ion cao nhất ? A Al2O3 B ScCl3 C NO2 D CCl4

Rzqust [24]

Answer:

Explanation:

hợp chất nào có khả năng là hợp chất ion cao nhất ?

A Al2O3?

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3 years ago