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3 years ago

The other half is posted !!!!!!

Chemistry

2 answers:

ycow [4]3 years ago

8 0

Where are the instructions?

koban [17]3 years ago

3 0

Answer:

this isn't an answer just need these points

Explanation:

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In the following list, only ________ is not an example of a chemical reaction. the production of hydrogen gas from water the tar

Vika [28.1K]

Answer: Option (c) is the correct answer.

Explanation:

A chemical reaction is defined as the reaction where a chemical bond will break in order to form a new bond due to the formation of a new substance.

For example, $2Na + Cl_{2} \rightarrow 2NaCl$

Here, NaCl is the new substance that is formed. A chemical reaction will always bring change in chemical composition of a substance.

The production of hydrogen gas from water, the tarnishing of a copper penny, charging a cellular phone and burning a plastic water bottle are all chemical reactions.

Whereas a reaction where no change in chemical composition of a substance takes place is known as a physical reaction.

For example, chopping a log into sawdust will change the shape but it will not bring any change in chemical composition of the substance.

Thus, we can conclude that in the following list, only chopping a log into sawdust is not an example of a chemical reaction.

8 0

3 years ago

Given the molar absorptivity for a species X of 1600 M-1cm-1 at a wavelength of 270 nm, and 400 M-1cm-1 at a wavelength of 540 n

Andre45 [30]

Answer:

Explanation:

From the given information:

At wavelength = 270 nm

$\varepsilon x_1 = 1600 \ m^{-1} \ cm^{-1} \\ \\ \varepsilon y_1 = 200 \ m^{-1} \ cm^{-1}$

At 270 nm

Suppose x is said to be the solution for the concentration of x and y to be the solution for the concentration of y;

Then:

$\varepsilon x_1 \ l + \varepsilon y_1 \ l= 0.5 \\ \\ A = A_1 + A_2$

$1600 xl + 200 yl= 0.5$

Divide both sides by 200

$8xl + yl = \dfrac{0.5}{200}$

$8x + y = \dfrac{0.5}{200}l$

Use l = 1cm (i.e the standard length)

Then;

$8x + y = \dfrac{0.5}{200} ---- (1)$

$\varepsilon x_2 x \ l + \varepsilon y_2 y \ l= 0.5 \\ \\ 40 xl + 800 yl = 0.5$

$x + 20 y = \dfrac{0.5}{400 \ l}$

since l = 1

$x + 20 y = \dfrac{0.5}{400 \ } --- (2)$

Equating both (1) and (2) together, we have:

$8x + y - 8x - 160 y = \dfrac{0.5}{200} - \dfrac{0.5 \times 8}{400} \\ \\ \implies - 159 y = \dfrac{0.5}{200} ( 1 - \dfrac{8}{2}) \\ \\ -159 y = \dfrac{-0.5 \times 3}{200} \\ \\ 159 \ y = 0.0075 \\ \\ y = \dfrac{0.0075}{159} \\ \\ y = 0.00004716 \\ \\ y = 4.7 \times 10^{-5 } \ M$

3 0

3 years ago

Uranium-238 had a half life of 4.5 billion years. A 100 g sample of U-238 has decayed until only 25 g remain. How long did it ta

Natasha2012 [34]

awnseris chemical hhhh Explanation:

6 0

3 years ago

How much heat (in kJ k J ) is evolved in converting 2.00 mol m o l of steam at 135 ∘C ∘ C to ice at -42 ∘C ∘ C ? The heat capaci

vovikov84 [41]

The total quantity of heat evolved in converting the steam to ice is determined as -12,928.68 J.

<h3>Heat evolved in converting the steam to ice</h3>

The total heat evolved is calculated as follows;

Q(tot) = Q1(steam to boiling point) + Q2(boiling point to ice) +Q3(freezing to -42 ⁰C)

where;

Q is heat evolved

Q = = mcΔθ

where;

m is mass, (mass of water = 18 g/mol)
c is specific heat capacity,
Δθ is change in temperature

Q(tot) = 2(18)(2.01)(100 - 135) + 2(18)(2.01)(0 - 100) + 2(18)(2.09)(-42 - 0)

Q(tot) = -12,928.68 J

Thus, the total quantity of heat evolved in converting the steam to ice is determined as -12,928.68 J.

Learn more about heat here: brainly.com/question/13439286

#SPJ1

8 0

2 years ago

NEED HELP ASAP! Newton's Law of Gravity says that any the effect of gravity between two objects depends on what two factors?

kari74 [83]

Answer:

C. Distance and mass.

Explanation:

Objects that have greater mass have more force of gravity between them.

3 0

3 years ago