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Elina [12.6K]
3 years ago
9

what is a double bond? A. a total of two covalent bonds between molecules. B. two covalent bonds between adjacent atoms in a mol

ecule. C. two covalent bonds between adjacent molecules
Chemistry
1 answer:
joja [24]3 years ago
4 0
C is what I think! Lol! I rhymed!
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A substance in the solid phase state of matter has ​
ElenaW [278]

Answer:

A variable shape that adapts to fit its container.

8 0
3 years ago
In 1838, botanist Matthias Schleiden, determined that all plants are composed of cells. In 1839, anatomist Theodor Schwann propo
Margarita [4]

Answer:

This question is incomplete; the complete part is:

A) All cell have a cell wall.

B) All cell arise from pre-existing cells.

C) All cell are capable of photosynthesis.

D) All cell can develop into any other type of cell.

The answer is B

Explanation:

The commonly known universal theory proposed in 1838 took the contribution from three remarkable scientists namely: botanist Matthias Schleiden, anatomist Theodor Schwann and biologist Rudolph Virchow. According to the question, Mathias discovered that all plants are made of cells, Schwann determined that all animals are made of cells while Virchow determined that all living things are composed of cells.

However, in addition to Virchow's discovery, he also discovered and proposed that "All cell arise from pre-existing cells", which till date forms part of the three components of the cell theory. The three parts are:

- Cell is the fundamental and basic unit of all living things.

- All living things are made up of one or more cells

- All cells arise from pre-existing cells

6 0
3 years ago
Which statement below best describes mutations?
Studentka2010 [4]

Answer:

C. Mutations are a change in DNA or a chromosome and can be helpful, harmful or may have no affect.

Explanation:

  • Mutations are spontaneous random changes that occurs in the genetic make up of an organisms. Mutations are rare and their rate of occurrence is random.
  • Mutations may occur on the gene level known as gene mutations or at chromosome levels called chromosomal mutations.
  • Mutations may be beneficial, harmful or have no effect on a given organisms. Harmful mutations cause disorders that may lead to abnormality or death of an organisms. Beneficial mutations improve an organisms adaptability to the environment.
8 0
3 years ago
Be sure to answer all parts. Styrene is produced by catalytic dehydrogenation of ethylbenzene at high temperature in the presenc
svlad2 [7]

Answer:

a) ΔHºrxn = 116.3 kJ, ΔGºrxn = 82.8 kJ,  ΔSºrxn =  0.113 kJ/K

b) At 753.55 ºC or higher

c )ΔG =  1.8 x 10⁴ J

    K = 8.2 x 10⁻²

Explanation:

a)                                 C6H5−CH2CH3  ⇒  C6H5−CH=CH2  + H₂

ΔHf kJ/mol                    -12.5                           103.8                      0

ΔGºf kJ/K                        119.7                         202.5                      0

Sº J/mol                          255                          238                      130.6*

Note: This value was not given in our question, but is necessary and can be found in standard handbooks.

Using Hess law to calculate  ΔHºrxn we have

ΔHºrxn  = ΔHfº C6H5−CH=CH2 +  ΔHfº H₂ - ΔHºfC6H5−CH2CH3

ΔHºrxn =     103.8 kJ + 0 kJ  - (-12.5 kJ)

ΔHºrxn = 116.3 kJ

Similarly,

ΔGrxn = ΔGºf C6H5−CH=CH2 +  ΔGºfH₂ - ΔGºfC6H5CH2CH3

ΔGºrxn=   202.5 kJ + 0 kJ - 119.7 kJ  = 82.8 kJ

ΔSºrxn = 238 J/mol + 130.6 J/mol -255 J/K = 113.6 J/K = 0.113 kJ/K

b) The temperature at which the reaction is spontaneous or feasible occurs when ΔG becomes negative and using

ΔGrxn =  ΔHrxn -TΔS

we see that will happen when the term  TΔS  becomes greater than ΔHrxn since ΔS  is positive  , and so to sollve for T we will make ΔGrxn equal to zero and solve for T. Notice here we will make the assumption that  ΔºHrxn and ΔSºrxn remain constant at the higher temperature  and will equal the values previously calculated for them. Although this assumption is not entirely correct, it can be used.

0 = 116 kJ -T (0.113 kJ/K)

T = 1026.5 K  =  (1026.55 - 273 ) ºC = 753.55 ºC

c) Again we will use

                       ΔGrxn =  ΔHrxn -TΔS

to calculate ΔGrxn   with the assumption that ΔHº and ΔSºremain constant.

ΔG =  116.3 kJ - (600+273 K) x 0.113 kJ/K =  116.3 kJ - 873 K x 0.113 kJ/K

ΔG =  116.3 kJ - 98.6 kJ =  17.65 kJ = 1.8 x 10⁴ J ( Note the kJ are converted to J to necessary for the next part of the problem )

Now for solving for K, the equation to use is

ΔG = -RTlnK and solve for K

- ΔG / RT = lnK  ∴ K = exp (- ΔG / RT)

K = exp ( - 1.8 x 10⁴ J /( 8.314 J/K  x 873 K)) = 8.2 x 10⁻²

8 0
3 years ago
Calculate the mole fraction of kbr (molar mass 119.00 g/mol) in a solution made by dissolving 0.30 g kbr in 0.400 l of H2O (d =
julia-pushkina [17]

The mole fraction of KBr in the solution is 0.0001

<h3>How to determine the mole of water</h3>

We'll begin by calculating the mass of the water. This can be obtained as follow:

  • Volume of water = 0.4 L = 0.4 × 1000 = 400 mL
  • Density of water = 1 g/mL
  • Mass of water =?

Density = mass / volume

1 = Mass of water / 400

Croiss multiply

Mass of water = 1 × 400

Mass of water = 400 g

Finally, we shall determine the mole of the water

  • Mass of water = 400 g
  • Molar mass of water = 18.02 g/mol
  • Mole of water = ?

Mole = mass / molar mass

Mole of water = 400 / 18.02

Mole of water = 22.2 moles

<h3>How to de terminethe mole of KBr</h3>
  • Mass of KBr = 0.3 g
  • Molar mass of KBr = 119 g/mol
  • Mole of KBr = ?

Mole = mass / molar mass

Mole of KBr = 0.3 / 119

Mole of KBr = 0.0025 mole

<h3>How to determine the mole fraction of KBr</h3>
  • Mole of KBr = 0.0025 mole
  • Mole of water = 22.2 moles
  • Total mole = 0.0025 + 22.2 = 22.2025 moles
  • Mole fraction of KBr =?

Mole fraction = mole / total mole

Mole fraction of KBr = 0.0025 / 22.2025

Mole fraction of KBr = 0.0001

Learn more about mole fraction:

brainly.com/question/2769009

#SPJ1

6 0
1 year ago
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