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masha68 [24]
3 years ago
8

A chemistry teacher carried out several demonstrations, and students recorded their observations. For one of the demonstrations,

a student concluded that a physical change took place, but not a chemical change. Which of the following observations could the student have made of the results of the demonstration?
Chemistry
2 answers:
PIT_PIT [208]3 years ago
4 0

Answer:

It demonstrates that it a physical change because you can't see nothing happening but something happening

Sry if it doesn't make sense

taurus [48]3 years ago
3 0

The given question is incomplete. The complete question is:

A chemistry teacher carried out several demonstrations, and students recorded their observations. For one of the demonstrations, a student concluded that a physical change took place, but not a chemical change. Which of the following observations could the student have made of the results of the demonstration?

a) Two colorless solutions were combined, and the resulting solution was pink.

b)  When a solid was added to a liquid, sparks were produced.

c) One piece of solid substance was changed into small pieces.

d) When two solutions were combined, a precipitate formed.

Answer: One piece of solid substance was changed into small pieces.

Explanation:

Physical change is defined as the change in which shape and size of a substance changes, There is no change in the composition of the substance as no new substance is forming. It is usually an reversible reaction.

Chemical change is defined as the change in which a change is the chemical composition takes place resulting in the formation of new substance. It is usually an irreversible reaction.

Indicators showing chemical changes are :

Color change

Characteristic odor

Formation of bubbles

Formation of precipitate

Thus the given change is a physical change as only the physical state i.e. size of solid substance was changed into small pieces.

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The color produce when the following compound is burnt LiCl NaCl KCl CaCl2
alexandr402 [8]

Answer:

LiCl - pink

NaCl - yellow

KCl - purple/blue-violet

CaCl₂ - orange/orange-red

Hope this helps.

4 0
3 years ago
The chemical formula for water is h2o. According to this formula what is the composition of a water molecule
sergejj [24]

Answer:

two hydrogen atoms and one oxygen atom

Explanation:

8 0
2 years ago
Temperate deciduous trees lose their leaves in Fall. Explain why trees in temperate rainforest and tropical rainforest don’t los
andrey2020 [161]

Answer:

So trees in temperate don't lose their leaves because the weather events aren't harsh enough.

Trees in tropical rainforest don't lose their leaves because they are a different type of tree known as evergreens that are green all year round.

Explanation:

Ok so first we'll define some things

Deciduous Trees=  Trees that lose all of their leaves for part of the year.

Trees shed their leaves trees to try and survive harsh weather events.

Temperate deciduous trees lose their leaves in fall to better survive the winter conditions of extreme cold and reduced daylight.

Temperate rainforests = An area that doesn't experience extremely cold or extremely hot temperatures or what we would call harsh weather events.

Broad-leaved trees in tropical rainforests are known evergreen, they are known as this as they are green all year round.

6 0
3 years ago
How many moles of nitrogen gas are there in 16.8 L of this gas at STP?
sweet-ann [11.9K]
According to Avogadro's Law, same volume of any gas at standard temperature and pressure will occupy same volume. And one mole of any Ideal gas occupies 22.4 dm³ (1 dm³ = 1 L).

Data Given:

                  n = moles = ?
                  V = Volume = 16.8 L

Solution:
               
As 22.4 L volume is occupied by one mole of gas then the 16.8 L of this gas will contain....

                           = ( 1 mole × 16.8 L) ÷ 22.4 L
                    
                           = 0.75 moles

Result:
           
16.8 L of Nitrogen gas will contain 0.75 moles at standard temperature and pressure.
4 0
3 years ago
How many joules of heat must be absorbed by 500g h2O @ 50CELCIUS to convert to steam @ 120 celcius?
nadya68 [22]

Answer:

Q = 1267720 J

Explanation:

  • Qt = QH2O + ΔHv

∴ QH2O = mCpΔT

∴ m H2O = 500 g

∴ Cp H2O = 4.186 J/g°C = 4.183 E-3 KJ/g°C

∴ ΔT = 120 - 50 = 70°C

⇒ QH2O = (500 g)(4.183 E-3 KJ/g°C)(70°C) = 146.51 KJ

∴ ΔHv H2O = 40.7 KJ/mol

moles H2O:

∴ mm H2O = 18.015 g/mol

⇒ moles H2O = (500 g)(mol/18.015 g) = 27.548 mol H2O

⇒ ΔHv H2O = (40.7 KJ/mol)(27.548 mol) = 1121.21 KJ

⇒ Qt = 146.51 KJ + 1121.21 KJ = 1267.72 KJ = 1267720 J

5 0
3 years ago
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