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earnstyle [38]
3 years ago
5

Why are chemical changes considered “unseen”?

Chemistry
2 answers:
atroni [7]3 years ago
6 0
<span>The correct answer here is that the reason chemical changes can be considered unseen, is because the alterations made within an element when it undergoes a chemical change occurs within the very atoms of the cell itself. In contrast with this, a physical change (such as a solid changing to a liquid through melting) does not change the element itself, but just it's physical form, so this can be seen easily to the human eye.</span>
enot [183]3 years ago
5 0

Answer is: chemical changes are considered "unseen", because they occur at the atomic level.

There are two types of substance changes: chemical and physical.

In chemical change (chemical reaction) new substances are formed, the atoms are rearranged (atoms are invisible to human eyes).

Physical property can be observed and measured without any changes in molecular composition. The same substance is present before and after the psysical change, just with different form or state of matter, this changes are seen by human eyes because of change of color or state of matter.

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What is the mass of 1.00 mol of oxygen (O2)?
Ad libitum [116K]

Answer:

Mass = 32 g

Explanation:

Given data:

Number of moles of oxygen = 1.0 mol

Mass of oxygen = ?

Solution:

Formula:

Number of moles = mass/molar mass

Molar mass of oxygen (O₂) is  32 g/mol

by putting values,

1.0 mol = mass/ 32 g/mol

Mass = 1.0 mol ×32 g/mol

Mass = 32 g

4 0
3 years ago
A compound contains 64.27% carbon, 7.19% hydrogen, and 28.54% oxygen. the molar mass is 168.19 g/mol. what is the molecular form
coldgirl [10]
Empirical formula is the simplest ratio of whole numbers of components in a compound 
calculating for 100 g of compound 
                                             C                             H                             O
mass                                  64.27 g                   7.19 g                     28.54 g
number of moles        64.27 g / 12 g/mol      7.19 g/1 g/mol     28.54 g / 16 g/mol 
                                        = 5.356 mol           = 7.19 mol           = 1.784 mol 
divide by least number of moles  
                                     5.356 / 1.784            7.19 / 1.784         1.784 / 1.784
                                      = 3.002                     4.03                     = 1.000
rounded off to nearest whole number 
 C - 3
 H - 4
 O - 1
empirical formula - C₃H₄O
 
 mass of empirical formula = 12 g/mol  x 3 + 1 g/mol x 4 + 16 g/mol x 1 = 56 g
molecular mass = 168.19 g/mol 
molecular formula is the actual ratio of elements making up the compound 
number of empirical units = molar mass of molecule / empirical mass
      empirical units = 168.19 g/mol  / 56 g = 3.00
there are 3 empirical units making up the molecular formula 
molecular formula = 3 x C₃H₄O

molecular formula = C₉H₁₂O₃

                 
5 0
4 years ago
When 8.21 l of c3h8 (g) burn in oxygen, how many liters of oxygen are consumed? all gas volumes are measured at the same tempera
just olya [345]
<span>8.21 L of C3H8(g) Lets take c as the molar volume at that temperature.
    c L <><> 5c L
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  8.21 L <><> x L
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3 years ago
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8 0
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Read 2 more answers
Which of these are components of DNA? Check all that apply.
Kipish [7]

Answer:

  1. deoxyribose sugar molecules.
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  5. phosphate molecules.

Explanation:

Hope it helps.

6 0
4 years ago
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